The stock Pontiac V-8 block is constructed of cast iron. When introduced in 1955, it displaced only 287 ci. Its robust design allowed immediate adaptability to future displacement increases. Though external dimensions remained very close to the original 287 design, the V-8 eventually displaced as much as 455 ci by increasing bore diameter and stroke length. With today’s long-stroke aftermarket crankshafts, a total displacement near 500 ci using a stock block is quite possible.
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Block Design
The basic block is compact and rigid. Its deck height is relatively tall at 10.24 inches as measured from the crankshaft centerline upward. The deck surface is very thick and uses ten 1/2-inch-diameter bolts, which pass through the deck surface and into individual bosses within the coolant jacket walls to retain the cylinder heads. The individual bosses limit cylinder distortion when the head bolts are torqued appropriately. The holes are also blind and do not extend into the water jacket, which would otherwise require thread sealer during installation.
The stock Pontiac V-8 block evolved from its original displacement of 287 ci in 1955 to as much as 455 by 1970 without grossly deviating from its original external dimensions. Its robust main saddles and thick deck surface are among the many features designed to improve rigidity and durability. Original 400 and 455 blocks are the most popular for modern performance builds up to 600 hp or slightly more.
When selecting a block for your build, a complete running engine makes a suitable candidate. I found this 1974 400 locally for $250 and confirmed that it retains its original 4.12-ci bore after removing the cylinder heads. With some hunting, you can likely find a similar bargain. I don’t recommend spending more than $500 to $700 for any Pontiac engine unless for a numbers-correct example.
Most Pontiac blocks from 1970 forward have four or five engine-mount bolt holes on each side, which allows easy installation into any chassis. Earlier blocks, such as this 1968 400, and even some very late 1970s blocks have a limited number, and that can present installation issues. While adapter kits are available, they may compromise durability in extreme applications. Be sure the block you select has the correct mounting points for your chassis.
A symmetric 90-degree design allows for easy and precise block machining. The main journal saddles are quite thick, which improves block rigidity and allows the use of long connecting rods for good rod-to-stroke ratio. From 1959 on, engines displacing between 326 and 400 inches contained a main journal diameter of 3 inches, while 421-, 428-, and 455-ci engines featured 3.25-inch journals. The main bearing caps are fastened to the block by two large bolts in most instances and located by dowel pins to prevent the caps from wandering during high-speed operation.
Oil is collected in a sump at the rear of the oil pan. It’s drawn in, pressurized, and dispersed by a positivedisplacement rotary pump that’s driven by the camshaft. The oil is filtered before it passes across the rear of the block and into a machined galley that runs parallel to the crankshaft on the left side. As the oil travels forward, it lubricates the camshaft, crankshaft, and left-side lifter bores. It then crosses over to the right side of the block at the front journal before traveling toward the rear lubricating the remaining lifter bores.
The original V-8 block design saw a number of changes over the years, and that can limit direct component interchange. That includes a variety of displacements, revised engine mounting points, transmission bellhousing bolt patterns, starter locations, main journal diameters, and cooling system variances. Other differences less concerning include the number of water jacket plugs and rocker arm oiling path.
Selecting a Stock Block
When considering a block for your particular build, any casting from 1965 and later is probably the best choice. Blocks of this era are constructed of high-quality iron and contain all of the desirable characteristics to accept most modern aftermarket Pontiac components and accommodate easy chassis installation. Some earlier blocks may be of similar or better quality (particularly the 1960s Super Duty castings) but such examples are rare and may present compatibility concerns with today’s parts.
Though 400 and 455 blocks are most popular for modern performance builds, the 455 was far more desirable for many years for its larger displacement and cost reflected it. It wasn’t uncommon to pay several hundred dollars for a usable core with standard dimensions. While the 455 allowed Pontiac racers to remain competitive with larger-cube engines of other makes, reliability issues in race applications were common. The area required to accommodate 3.25-inch-diameter main journals created excessive friction and was difficult to properly lubricate at high speed. The wider journal also compromised main saddle rigidity.
Beginning in 1968, Pontiac located the block casting number on a ledge just rearward of the number-8 cylinder. Many numbers were available. This particular block, number 488988, was used in late-1974 400 applications and contains all the desirable characteristics for performance use.
A block I recommend avoiding is number 500557, which was introduced in 1975 and commonly used through 1978, at which point 400 production ceased. Thickness in certain areas was reduced to save weight and roll pins were used in place of dowels for main cap retention. While completely suitable for low-RPM production applications and builds up to 400 hp or so, it doesn’t possess the durability required for high-performance use.
To improve the durability of its 1978–1979 T/A 6.6 engines, Pontiac revived the 481988 casting, which was beefier than the 500557 used elsewhere. To identify the new casting, Pontiac added a large “XX” in several places. That includes on the lifter bore, which otherwise commonly contained the last two digits of engine displacement (such as “55” denoting 455). The XX-481988 blocks are as durable as any earlier block, and can be considered an excellent choice for performance use.
The somewhat-recent introduction of long-stroke aftermarket crankshafts with 3-inch main journals has revolutionized the hobby. When compared to a 455, a 400 block is far more plentiful, making it cheaper and easier to find. Any performance enthusiast or competitive racer can easily achieve displacement greater than 460 ci using a typical 400 block and an aftermarket crankshaft. The smaller journals reduce bearing speed and improve block integrity, giving racers the performance and reliability required for high-speed operation.
While most any 400 block produced between 1967 and 1978 is a suitable candidate for high-performance use, there’s one block casting I strongly suggest avoiding entirely. To shed total vehicle weight, Pontiac revised its 400 during the 1975 model year. The svelte 400 block is easiest identified by its 500557 casting number, and lacks the durability required for high-performance applications.
When searching for a stock block, purchasing a complete and running engine is fine so long as you’re aware that you have no way of predetermining the block’s condition and capability. It may be easiest to find a casting that’s completely disassembled and thoroughly cleaned so every portion of it can be thoroughly inspected. A grungy block must be properly cleaned so the block can be inspected to determine if it’s a suitable candidate.
The deck surface of a Pontiac block is very thick, and can measure more than .375 inch. Surfacing to remove irregularities and improve gasket seal, which is known as “decking,” should be part of any rebuild. Slightly more can be removed so the deck surface and piston face are level to maximize quench area and promote greatest performance. Gross decking can affect compression distance on subsequent rebuilds, however.
A honing plate (or torque plate) is an excellent investment if you’re serious about performance. It replicates the load a block sees when a cylinder head is installed. A quality machine shop uses it to account for cylinder distortion during machining, but it can be beneficial for home use too. That includes curing time for water jacket filler and for light cylinder honing during a refresh. BHJ offers steel and alloy units for the Pontiac V-8.
All cylinder machining should be performed with a honing plate installed. Most Pontiac blocks tolerate an overbore of at least .030 inch, and possibly up to .060 inch or slightly more. Since production variances and core shift are normal, I recommend measuring the cylinder wall thickness using an ultrasonic tester before machining. That allows you to calculate thrust wall thickness and ensure it’s at least .120 inch after boring and honing.
Once perfectly clean, the block should be magnetically checked for cracks, and then closely inspect for porosity or rust issues externally as well as in the water jackets. A bright light and small mirror can provide you with an idea of what the block looks like internally, particularly toward the bottom of the cylinders. You should also inspect the main saddles and bulkheads to ensure uniformity throughout and look for casting voids or signs of core shifting.
If you have access to an ultrasonic thickness tester, it’s wise to measure cylinder walls thickness on all sides, but the thrust side is most critical. A nominal wall thickness of at least .150 inch on the thrust side, and .100 inch elsewhere should provide plenty of wall material for boring. There’s no concern using a block with greater wall thickness, but anything less than about .120 inch on the thrust side after machining may fail in extreme applications.
If you have any doubt about your own opinion, take along an experienced friend or a trusted machinist for a second opinion. It can never hurt!
Stock Block Modifications
A stock Pontiac block is completely adequate for most high-performance builds. Good rebuilding and reconditioning techniques, which includes thoroughly cleaning the oiling passages and precise machining with modern equipment generally produces a block that’s well equipped for applications producing up to 600 hp, or slightly more.
The deck should be machined to provide a smooth and consistent surface for optimal gasket seal. Generally measuring somewhere near 3/8 inch thick, it can be machined liberally without worrying about compromising its integrity. Any time material is removed from the deck surface, you need to physically verify that the cylinder head bolts do not bottom out with the cylinder head installed.
Most Pontiac blocks can tolerate an overbore up to .060 inch, and possibly more after proper thickness testing. Boring and honing should always include a honing plate. Also called a “torque plate,” it’s a rigid piece of steel or aluminum that bolts to the block’s deck surface and replicates the load it sees when a cylinder head is installed.
The front oil galley plugs in most stock Pontiac blocks are a press-fit design that are driven into place and staked for maximum retention. Loose-fitting plugs sometimes push out when exposed to very high oil pressure, and that can result in a massive internal oil leak. A popular modification to is tap the front holes to accept common 3/8-NPT pipe plugs. Use caution when installing the plugs, however. If the plugs are threaded in too far, oil flow through the block may be restricted.
When Pontiac developed its tunnel-port Ram Air V, additional ribbing was added to connect the lifter bore banks in the block’s lifter galley, improving rigidity and durability. Though the R/A V never reached regular production, the feature was incorporated into the 1973–1974 SD-455. It’s beneficial when running a camshaft with very aggressive specifications.
Extreme camshaft duration and/or valvespring pressure creates an excessive amount of side loading on the lifter during normal operation. That can cause the lifter bores of a typical Pontiac V-8 block to crack and/or break. The Mega Brace by SD Performance is a bolt-in kit that strengthens the lifter galley in a stock block. It’s an excellent design that’s used by many professional Pontiac engine builders.
The stock Pontiac block delivers a large volume of pressurized oil for proper hydraulic lifter function. Solid lifters do not require it, and that can require the installation of lifterbore restrictors that limit oil flow. The modification consists of cutting several threads into the lifter bore using a 1/4-20 or 1/4-28 tap, and then inserting stainless-steel set screws with a .030- to .060-inch hole to effectively limit oil flow. A few manufacturers now offer Pontiac-specific solid lifters that are internally restricted, lessening the need for this modification.
Hard Blok is one of the best water jacket fillers available today. It doesn’t generate an excessive amount of heat during the curing process, and doesn’t expand when exposed to temperature increases during normal operation. Even though distortion is minimal, I recommend that it be poured and cured before any block machining.
Adding water jacket filler is an excellent way to improve the rigidity of any block. Poured in as a liquid, it encapsulates the cylinder bottoms by replacing the coolant that otherwise surrounds them. Once cured it essentially becomes a permanent part of the block, preventing distortion and absorbing harmonics. Installation of a honing plate and the main caps during the pour is strongly recommended to maintain ideal block dimension during the curing process.
“Hot honing” consists of heating the block until it’s near its normal operating temperature (around 200 degrees F) before machining. While it’s not practical or necessary for every performance level, hot-honing may benefit those chasing every last horsepower when racing at the most competitive levels.
An aggressive roller camshaft and the valvespring pressure it requires greatly stresses the lifter bores of a stock Pontiac block. Lifter bore brace kits, such as the Mega Brace from SD Performance contain formed plates that are bolted, epoxied, and/or welded into the lifter valley to improve lifter bore strength.
Another common modification performed to the lifter bores in a stock Pontiac block is to tap the lubrication holes and insert small restrictors whenever a solid-lifter cam is used. Stock lifter bores supply a relatively large volume of oil for proper hydraulic lifter operation. Solid lifters simply pass oil through to the rocker arms, and if restrictors are not installed to limit oil flow, oil will freely flow to the top of the engine, reducing the supply available for the main journals. Many Pontiac builders still offer lifter bore restrictor kits, but many modern solid lifters (flattappet and roller alike) are restricted internally to control the amount of oil that reaches the top end.
Water Jacket Filler
A stock Pontiac block can be dimensionally unstable if subjected to excessive cylinder wall side loading from a long stroke crankshaft, extreme cylinder pressure, and/or excessive RPM associated with max-performance engines. Another instance may be if the cylinder walls are at the minimum recommended thickness after boring. That instability can lead to a number of operating issues that can negatively impact performance or result in engine failure.
Water jacket filler is a thick liquid that’s poured into the coolant jacket of a block, encapsulating the cylinders. Once permanently set, it makes a block less susceptible to flexing, which improves cylinder-wall strength and seal, dampens harmonics, and reduces main-cap walking. If a torque plate is available, installing it just after pouring ensures that the cylinders are located properly during the curing process. Most water jacket fillers expand slightly while curing, and because of that I highly recommend that machining be performed only after the filler has cured completely.
Most builders suggest filling the block to the bottom of large freeze plug holes in the side for maximum durability in applications producing at least 600 hp. It reduces volume of coolant circulating in the block, and that can possibly increase oil temperature slightly. A “short fill” is best suited for street/strip engines producing more than 550 hp where some additional rigidity is beneficial, but still allows for plenty of coolant circulation. It typically consists of filling the block until the filler reaches about one inch below the large expansion plug holes in the side. A variety of water jacket fillers are on the market today. I recommend premium filler such as Hard Blok or that from Ken’s Speed & Machine Shop. Following the supplied mixing and installation instructions provides the best results.
Main Caps
The center three main journals of a Pontiac V-8 endure the greatest load, and the corresponding bearing caps were generally retained by only two bolts early on. Pontiac determined that using beefier main bearing caps and four retaining bolts in the number-2, -3, and -4 journals improved rigidity and reliability, especially in applications with 3.25-inchdiameter main journals, where more of the main cap is lost to journal area. Factory four-bolt caps are commonly found on certain Ram Air, H.O., and Super Duty engines of the 1960s and 1970s. Most Pontiac blocks during that era were machined to accept two-bolt caps only, but 455 blocks produced through about 1974 were mostly machined for four-bolt caps even though two-bolt units were installed most often.
Pontiac used two-bolt main caps in most of its production engines. Although some blocks were drilled and tapped for four-bolt caps, most were originally fitted with twobolt units like this. They are sufficient up to about 600 hp. Honing improves alignment and bearing life without grossly altering the position of the crankshaft centerline.
Four-bolt main caps were used at the center three journals in high-performance applications. The four-bolt cap is larger than a two-bolt unit, and serves to improve main saddle rigidity and overall durability, particularly with 3.25-inch main journals. Stock Pontiac caps were constructed of a cast-iron alloy. Installing used caps onto another block requires proper machining.
Pro-Gram Engineering produces topquality aftermarket main caps for the Pontiac V-8 constructed of billet steel. They’re ideal for high-performance applications where additional cap strength is required. Though Pro-Gram produces all five main caps for 3- and 3.25-inch blocks, the center three are retained by four straight bolts or with angled outer bolts. The block and caps must be machined accordingly.
A main cap must offer some absorptive quality to prevent main saddle fatigue. Milodon’s ductile-steel main caps are an excellent high-strength choice for such applications. Only available for the center three journals and with four straight bolts, they install and machine easily and offer the durability required for the most extreme applications.
Stock Pontiac main caps are quite durable and adequate for power levels approaching 550 hp. Factory four-bolt caps can likely sustain even greater power levels. At about 550 hp aftermarket four-bolt main caps should strongly be considered for the center three journals. Installing four-bolt caps isn’t as easy as bolting them on, however. A block and its main caps are a precision assembly that’s machined as a unit. Whenever a different main cap is used, whether a used original from another block or a new aftermarket unit, it must be precisely machined. That can include align-boring, thrust machining, and/or possibly relocating or resizing the dowel holes.
Billet-steel main caps are very strong and a few different aftermarket companies offer Pontiac V-8 units. Lesser-quality steel caps can be too hard, which makes them extremely difficult to machine. In those instances, the line-bore cutting equipment can bounce erratically, removing valuable material from the block in the process. Once installed, the main caps become an integral part of the block and improve rigidity while absorbing crankshaft shock load. Lesserquality billet caps can also be so hard that they resist shock load, leaving the block to absorb it all. Over time the block can fatigue and fail.
I feel the best billet main caps available today for Pontiac V-8s are produced by Pro-Gram Engineering. They’re strong enough to add significant benefit, yet machine relatively easily and exhibit excellent dampening ability. Pro-Gram offers complete main caps for all five journals in 3- and 3.25-inch diameters. While the front and rear caps are sold individually, the center three are sold as a set and are designed for four-bolt retention only, with straight or splayed outer bolt options. Pro-Gram main caps sell for about $300 and can be purchased directly from the manufacturer or from your favorite Pontiac vendor.
Milodon has been producing highquality ductile steel main caps for the center three journals of Pontiac V-8s for several years. Retained by four straight bolts, the caps are very strong and install relatively easily. An added benefit is that the thrust surface on the number-4 cap is the same diameter as the block, which means less machine work when compared to others. Expect to spend around $300 for a set.
Aftermarket Blocks
Though complete failure with a stock block is rather rare when output is less than 750 hp or so, there are distinct applications where an owner is looking to grossly increase displacement, or the intended performance level surpasses the capability of a stock design. The cost to prepare a stock block for a race application is nearly as much as the aftermarket Pontiac V-8 blocks available today. New blocks that contain additional material in critical areas are available for hobbyists looking to go to the next performance level, and are an excellent investment if future performance modifications are planned.
Two separate companies presently produce aftermarket Pontiac V-8 blocks. Each contains external dimensions similar to an original Pontiac unit and will accept many original Pontiac pieces, but are generally much beefier throughout. AllPontiac.com produces its cast-iron IA II block and an all-new aluminum casting. K&M Performance produces its MR-1 in cast iron or cast aluminum. Available from many Pontiac vendors, the aftermarket blocks are an excellent foundation for most max-performance applications, especially where displacement of 541 inches, and possibly more is desired.
Whether cast-iron or aluminum, aftermarket Pontiac blocks are designed to allow for easy installation into any chassis. Each side contains the appropriate bosses to accept most original engine mounts. It also accepts the original oil dipstick tube that’s driven into the block. Coolant jacket plugs are press fit or screw in, depending upon the manufacturer.
There are a few different aftermarket Pontiac V-8 blocks presently available that are ideal for applications approaching 750 hp and beyond. AllPontiac.com manufactures two distinct units. The IA-II is a cast-iron block that’s been on the market for several years, while the all-new aluminum block was a recent release. Both generally boast beefier main saddles and four-bolt main caps to significantly improve bottom end rigidity, particularly when using a very long stroke aftermarket crankshaft measuring 4.5 inches or more to produce a maximum displacement of 541 ci.
K&M Performance produces two aftermarket Pontiac V-8 blocks. They are nearly identical, except the MR-1 is constructed of cast iron, while the MR-1A is constructed of cast aluminum. A maximum displacement of 541 ci is possible. The lifter galley is heavily reinforced to accommodate the most radical camshaft and the main saddles are much thicker throughout.
The aftermarket blocks from AllPontiac.com and K&M Performance feature steel main caps and high-quality main studs. The center three caps are designed for four-bolt (or studs in this case) retention with outer-holes angle for maximum block rigidity. The main caps are drilled to accept a stock windage tray and/or oil dipstick tube.
The IA II block is constructed of high-nickel iron and features siamesed cylinders that tolerate a bore diameter up to 4.4 inches while maintaining a wall thickness that’s nearly .300 inch thick. The deck surface measures .750-inch thick and is delivered “dry.” The coolant passages must be drilled for “wet deck” applications. A tall-deck option that increases compression distance for specialized applications is also available. The lifter galley is greatly reinforced and is designed to accommodate the very long duration and high-lift camshafts that can damage or destroy the lifter bores in a stock Pontiac block.
Main journals are available in 3- or 3.25-inch diameters. Billet-steel main caps are standard, and the center three are a four-bolt design with angled outer bolts. All caps are registered to the main saddles and use larger 3/8-inch dowel pins for positive location to prevent walking, which can negatively affect oiling and bearing alignment at high RPM. The camshaft oiling passages that extend upward from the main journals are drilled smaller to strengthen the center of the block and prevent cracking in extreme conditions.
Main registering creates an oil pan rail that’s .125 inch deeper than stock. It improves block rigidity, but also requires a slightly longer oil pump driveshaft, which AllPontiac.com supplies. The IA II block comes with threaded freeze plugs and a bellhousing flange containing two distinct bolt patterns for both Buick-Olds- Pontiac or Chevy-type transmissions. It also features five mounting holes per side to accommodate any original chassis motor mounts. At about 250 pounds with main caps, the IA II block weighs 40 to 50 pounds more than a race-prepped stock block, but the extra weight is well worth it the IA II is extremely durable. Expect to spend around $3,000 for a basic IA II block. A wide variety of options are available at extra cost.
AllPontiac.com has recently developed and released a completely new lightweight aluminum Pontiac block for those most serious about performance. While containing many of the same design features and options as the castiron IA II, the high-quality aluminum casting is even beefier than its iron counterpart. It weighs nearly 140 pounds with the main caps, or about 115 pounds less than the cast-iron piece, but with a nearequal amount of durability. Expect to pay nearly $5,000 for the standard block. Many extra-cost options are available. K&M Performance produces the castiron MR-1. Many mistakenly believe that it’s a copy of the IA II, but the MR-1 was actually designed to eliminate the weaknesses associated with the stock Pontiac block in max-performance applications while accepting as many stock Pontiac pieces as possible. The MR-1 allows for a bore diameter up to 4.4 inches while maintaining a wall thickness of .200 inch. The deck surface is very thick and is drilled for “wet deck” applications. The coolant passages are sized to accept common pipe plugs after tapping. The lifter galley is heavily reinforced.
The MR-1 is available with 3- or 3.25- inch main journals. Billet-steel main caps are located using typical 5/16-inch dowel pins. The center three are retained by four bolts and the outer most bolts are angled for better block integrity. Like a stock Pontiac block, the MR-1 uses pressed freeze plugs and the oil pan rail is in its original position, which allows the use of many typical off-the-shelf Pontiac parts. A typical MR-1 block weighs around 250 pounds and features five mounting holes per side for ease of installation. The base block sells for around $3,000 and many extra-cost options are available. K&M Performance states it’s capable of safely enduring up to 2,500 hp or slightly more.
Shortly after introducing the cast-iron MR-1, K&M Performance developed and released an aluminum variant known as the MR-1A. Essentially a cast-aluminum copy of the iron MR-1, the blocks share the same design improvements and tooling. At a svelte 125 pounds, the MR-1A weighs about half as much as its cast-iron brethren, but because aluminum isn’t nearly as durable as iron, K&M Performance presently recommends it for applications up to 1,500 hp. Pricing starts around $4,500 and many extra-cost options are available. For the most serious racer, K&M Performance also produces a billet-aluminum Pontiac V-8 block on a custom-order basis. Expect to spend around $10,000 for what may be the strongest Pontiac block ever available.
Camshaft Bearings
Camshaft bearings are not required to carry very heavy loads. Generally a onepiece, two-layer design, it includes a steel shell and a very soft overlay. ACL, Clevite, Dura-Bond, Federal-Mogul, and King produce quality stock-replacement cam bearings suitable for most applications.
Dura-Bond offers a performance bearing that better resists the high valvespring pressures associated with aggressive roller camshafts. It even offers an optional dryfilm lubricant coating intended to reduce friction in extreme applications. While most cam bearing sets come in standard size, Dura-Bond also offers a .010-inch oversize for instances where honing the camshaft tunnel is necessary.
Camshaft bearings generally are not subjected to the same pressure as other engine bearings. The stock replacement Pontiac units available from many sources are usually more than sufficient for the moderate spring pressures associated with hydraulic and solid roller camshafts. Cam bearings must be installed using the proper equipment or damage can result.
Dura-Bond offers a high-quality Pontiac camshaft bearing set that features a dry-film lubricant coating. The coating reduces friction in applications where extreme valvespring pressure can damage standard bearings, such as with a very aggressive solid roller camshaft with high-valve lift.
Specific camshaft bearing sets with needle rollers are available for other makes. They can be adapted for use in the most severe Pontiac applications where the highest camshaft loads exist. The block’s camshaft tunnel must be bored accordingly to accept the oversize bearings, however, and that can remove valuable material within the main saddle of a stock Pontiac block, possibly compromising integrity. Roller cam bearings are a more feasible option when using a beefier aftermarket block for a build.
Rear Main Seal
Pontiac originally used a woven rope constructed of graphite-coated asbestos to seal its V-8’s rear main journal. The two-piece seal was packed into a corresponding groove machined into the block and main cap. The seal grooves had cavities drilled in them. As the rope was packed firmly into place during installation, it filled those cavities, effectively anchoring it and preventing rotation during operation. Excess portions of rope were then trimmed away, and the main cap installed.
Asbestos was chosen for strength, with a graphite coating to reduce friction. The original rope seal worked quite well for many years. It was lubricated during normal operation by small grooves on the crankshaft contact surface. While some oil “wicking,” or seepage that causes an occasional drip can be considered normal, larger leaks that result in small puddles were rather uncommon. New OE-spec replacement seals, such as those from Fel-Pro, were also constructed of asbestos and rarely problematic if installed as Pontiac originally instructed.
Government legislation eventually restricted the use of asbestos and companies were forced to find new materials for rope seal construction. Fel-Pro’s solution was braided fiberglass with a graphite coating. When compared to an original asbestos unit, the fiberglass replacement was less flexible and slightly more difficult to install, but it was effective.
Fel-Pro changed the base material of its rope seal from fiberglass to Kevlar in 1998. Since Kevlar better tolerates heat, Fel-Pro felt it would improve longevity. Though the recommended installation is identical to that of its predecessors, the Kevlar seal is even more difficult to work with than fiberglass. It’s much firmer and that makes it even more difficult to pack and trim accordingly. In fact, it’s not uncommon to use several fresh razor blades trimming a single seal during an installation.
Kevlar rope seals are generally included in every modern Fel-Pro engine gasket set. While I feel most other Fel-Pro gaskets offer the best functionality, the modern rope seal is one to avoid. It isn’t very forgiving and can leak severely even with careful installation. Though used successfully on occasion, most report poor results. Fel-Pro reports it has no plans to deviate from the current design since it’s as close to OE-spec as modern regulations allow. That has forced many hobbyists and professional engine builders to resort to other alternatives.
The rear main seal groove machined into the block and cap features drilled holes to anchor the original rope main seal and prevent it from rotating during normal operation. These holes must be filled with silicon sealer to prevent oil leaks when using an aftermarket lip-type seal. Aftermarket blocks and main caps do not contain these anti-rotation holes, so a small roll pin is required when using an aftermarket rope seal. Also note that the seal diameter varies among 3- and 3.25-inch blocks.
Pontiac originally used a rope seal constructed of woven asbestos (bottom), and it performed quite well. Modern replacements are constructed of woven fiberglass or Kevlar (top) and can be much more difficult to work with. Unless you have a supply of NOS originals, avoid the modern replacement because severe leaks can result even with careful installation.
A lip-type seal like this from BOP Engineering is an excellent design that consists of a Viton-coated steel core. The lip is designed to remain in constant contact with the crankshaft’s seal surface, essentially eliminating leaks. It’s compatible with the serrated lubrication grooves found on stock-type cranks, but journal polishing can be necessary.
The GraphTite seal from Best Gasket is a modern rope replacement that’s constructed of graphite-coated Teflon strands. It fits and functions like an asbestos original and can be relatively leak free when installed as directed. It’s an excellent choice, but I recommend using it only with crankshafts that contain serrated lubrication grooves.
ARP offers specific bolt kits for many Pontiac cylinder heads including castiron originals and popular aftermarket units. It also offers a cylinder head stud kit for max-performance applications. If ARP doesn’t offer a specific fastener kit for your particular cylinder heads, it can assemble a custom set to accommodate your needs.
Cylinder head studs reduce the amount of twisting force the block sees during tightening and can provide a clamping load that’s more consistent. I recommend ARP cylinder head studs when performance exceeds 650 hp. ARP’s specific moly-based thread lubricant on the threads and under the washers during install yields the best results.
Four-bolt main caps improve main saddle rigidity, but angled outer bolts draw the entire block together. “Splayed” main caps significantly make the outer block walls an integral part of the main saddle, improving overall block strength. An original two-bolt Pontiac block can easily be modified to accept splayed caps. Aftermarket Pontiac blocks feature splayed caps with main studs as standard equipment.
Pontiac main cap bolts were quite reliable, but modern fasteners may be a better option as the originals are 30 to 40 years old. ARP offers complete stud kits specifically designed for two- and four-bolt Pontiac main caps. In addition to starting with a new fastener, the studs eliminate the twisting force that main saddles otherwise see when you tighten the bolts. A stock windage tray and the oil pan can sometimes interfere with the main studs during assembly, but it can be easily corrected.
A lip-type rear main seal has been commonly used by various other auto manufacturers for many years. It’s generally constructed of a temperature-resistant rubber material such as neoprene and the “lip” is a formed “flap” that remains in constant contact with the sealing surface on the crankshaft. The rubber seal originally designed for certain large-cube Cadillac V-8s is a shape and size similar to that required for a Pontiac. Many hobbyists have successfully retrofited a Cadillac seal into their Pontiac, but installation is rather complex. Careful installation does yield positive results in most cases but anything less can result in a significant leak.
In 2000, BOP Engineering introduced a new molded lip-type seal specifically for the Pontiac V-8 and it proved to be an immediate success. It is constructed of a hardened steel core coated in Viton, a pliable material that’s oil and temperature resistant. It features a multiple-lip design that’s intended to improve oil control. A lip-type seal requires near absolute concentricity for maximum sealing ability. Pontiac didn’t hold the depth of the rear seal groove to any particular tolerance during machining, however. Since the rope seal was pliable, there wasn’t a great need for the groove to be precisely concentric to the crankshaft centerline.
BOP suggests a variance of no more than .010 inch from the crankshaft centerline for proper operation of its seal. I’ve found that closely following BOP’s installation instructions provides excellent results. A similar seal from Tin Indian Performance is also available, and though I have no direct experience with it, I suspect it performs as well.
A new Pontiac V-8 rope seal was introduced around 2007. The GraphTite seal from Best Gasket is constructed of braided Teflon that’s coated with graphite. It fits and installs like an asbestos original, and comes with detailed instructions, cutting blade, and template. More recent kits include a small roll pin to positively locate the seal when used with the aftermarket Pontiac V-8 blocks and caps, which lack the anti-rotation holes of an original. I have found it provides an excellent seal.
It’s best to use one of the aftermarket rear main seal options mentioned above. The type that’s best for you is often personal preference, but it can also depend upon the concentricity of the seal groove in the block and main cap. I suggest physically measuring the concentricity of your Pontiac block before deciding which rear main seal to use in your project.
Fasteners
When developing its V-8, Pontiac used 1/2-inch-diameter cylinder head bolts for maximum retention. An original Pontiac bolt in excellent condition can be reused several times, but there’s sometimes no way of knowing how many times it’s been previously used. Reproduction head bolts are available and the quality can range from very good to very poor. Investing in high-quality aftermarket cylinder head fasteners is the best choice.
Automotive Racing Products (ARP) produces a variety of premium automotive fasteners. It offers complete sets containing bolts in the proper lengths required for original Pontiac D-port and round-port cylinder heads as well as the aftermarket Edelbrock offerings. Custom sets for other aftermarket cylinder heads are also available. It’s best to check with the cylinder head manufacturer to determine exactly what’s required.
When installed as ARP suggests, using its specific moly-based thread lubricant, you can expect excellent results. I strongly suggest measuring the overall length of each bolt and its corresponding hole in the block to be sure the bolt doesn’t bottom out and provide a false torque reading during installation. This is especially important if the deck surface of the block and/or cylinder heads has been machined by any amount.
Fel-Pro offers two different Pontiac cylinder head gaskets that share the same basic shape and size. The design is a compilation of the many stock replacement units Fel-Pro offered over the years, and it’s compatible with most popular Pontiac blocks. PN 8518 (top) is a stock replacement unit while PN 1016 (bottom) is a high-performance gasket with a solid-steel core and premium fire rings. Completely coated in Teflon, Fel-Pro recommends installing its head gaskets dry.
A drawback to Fel- Pro’s cylinder head gasket is that its coolant holes are rather large and located fairly closely to the combustion ring. It’s quite visible when overlaid on an NOS original Pontiac head gasket (shown here). If the ring is compromised in any way, compression can push past the Fel-Pro gasket and enter the coolant system, which can result in major damage. While it may not be a concern for applications producing 700 hp or so, it can be an issue with forced induction or an extreme compression ratio.
Composition cylinder head gaskets from Butler Performance were developed using the original Pontiac blueprints. This design consists of a steel shim with a graphite coating on one side, and can provide excellent seal when combined with copper sealer. Butler Performance was able to size and locate bore-diameter and coolant passages for specific applications just like the originals. It’s easy to see how Butler ’s 421-spec unit (top) differs from the 400/455 unit (bottom).
When approaching the 650-hp level, it may be best to consider ARP’s cylinder head stud kit as opposed to bolts for improving retention. The stud is threaded into the block and a nut and washer assembly applies the clamping load. The stud eliminates the twisting that otherwise occurs when threading a bolt into the block, and it stretches more smoothly when torque is applied to the retaining nut. It reduces block distortion and improves clamping consistency and thread life.
The fasteners that Pontiac used to secure the main caps are of the highest quality. Those bolts are, however, more than 40 years old in most instances. If you or your machinist feels new fasteners are necessary, ARP offers a complete stud kit for two-bolt and four-bolt Pontiac V-8s.
The main studs offer the same advantages as cylinder head studs, and that includes less twisting on the block, clamping load consistency, and improved thread life. ARP main studs can be used in conjunction with stock main caps at any point, but are required with aftermarket main caps, which may or may not include new fasteners for installation.
Head Gaskets
A cylinder head gasket is designed to keep combustion heat and pressure within the cylinder and prevent coolant that passes between the block and head from leaking outward or into the cylinders. Should combustion pressure blow past or burn through the gasket’s combustion armor, escaping compression generally leads to complete gasket failure, and that can lead to significant engine damage if not detected in time. The head gasket Pontiac used for its V-8 was a composition construction consisting of a coated steel core. Many companies produced stock-replacement Pontiac head gaskets over the years, but few were as good those originally supplied by Pontiac.
MLS gaskets are the ultimate in cylinder sealing. The multiple layers allow for varying degrees of thermal expansion while providing maximum sealing capability in applications where extreme cylinder pressure exists. MLS head gaskets are commonly used by all auto manufacturers in modern production vehicles and are an excellent choice
Cometic manufactures premium MLS cylinder head gaskets. It offers a variety of options for traditional Pontiac V-8 blocks as well as the aftermarket offerings with various bore diameters and compressed thicknesses. Its gaskets are an excellent choice for maximum-performance applications, and are completely compatible with stock rebuilds too.
When cylinder heads and blocks are surfaced, the equipment leaves behind a finishing pattern. The roughness of the finish must be compatible with the cylinder head gasket or it can be torn apart as the block and heads expand and contract during normal operation. Most gasket manufacturers publish a roughness average (RA) range for their gaskets. It’s very important to follow the RA recommendations for maximum gasket reliability.
Fel-Pro introduced PN-8518 for the Pontiac V-8 during the 1970s. Containing a bore diameter of 4.3 inches and a preflattened thickness of .041 inch, it’s a stock-replacement design that’s compatible with most Pontiac blocks. Constructed of a perforated steel core with a Teflon outer coating, it features tinplated steel combustion armor. PN-8518 head gaskets sell for about $60 per pair and are an affordable choice for any stock rebuild, and even performance applications with a compression ratio up to 10.5:1, or slightly more.
A second Pontiac offering appeared in the Fel-Pro catalog during the early 1980s. PN-1016 is specially designed for high-performance applications with high compression and/or combustion pressure. Constructed of a Teflon-coated solid-steel core, it features stainlesssteel combustion armor and a wire ring combustion seal for maximum combustion containment. It contains a chamfered bore diameter or 4.3 inches and pre-compressed thickness of .039 inch. Selling for less than $80 per pair, it’s a good choice for naturally aspirated engines with a maximum compression ratio of 12:1 and/ or mildly boosted applications.
In the early 1990s Butler Performance (BP) began offering its own composition cylinder head gasket using original Pontiac blueprints. It features a steel core with graphite coating on one side. BP revised the coolant passage sizes to closer match those in the block to improve reliability. Available with various bore diameters, it compresses to about .045 inch after installation. BP recommends a light coating of copper sealer on the steel side for maximum block seal. BP’s composite gaskets are very durable and a popular choice for compression ratios up to 11.5:1 or moderately boosted engines. A pair sells for less than $50.
Copper head gaskets have long been the only choice for max-performance engines with extreme cylinder pressure and/or combustion heat. The durable copper construction prevents the blowouts and/or burning that can occur when exposing composition gaskets to high levels of nitrous oxide or boost. It’s often combined with a wire O-ring, which resides in a machined groove in the block and prevents combustion pressure from blowing past the gasket. A copper gasket’s main drawback is its inefficiency to prevent coolant or oil leaks. Liberal coats of surface sealer during installation were once required, but SCE Gaskets offers topquality copper gaskets with built-in seals, and it’s an excellent concept. Copper gaskets are available from several companies and remain the best choice for extreme performance applications.
Multi-layer steel (MLS) gaskets are today’s choice for most max-performance applications. As the name implies, an MLS gasket is constructed of multiple layers of steel gaskets with a tough-yetpliable exterior coating. The multi-layer design improves sealing by spreading the load across the entire gasket surface while the outer coat seals the gasket against most types of mating surface or load. MLS cylinder head gaskets have proven to be as durable as any copper unit in all but the most extreme applications, but they lack the sealing issues that plagued racers for years.
Cometic is the only company that presently produces MLS cylinder head gaskets for the Pontiac V-8. Bore diameters range from 3.75 to more than 4.4 inches and standard compressed thickness measures .040 inch. Any other bore diameter and thickness from about .020 to .120 inch is available on a customorder basis. Suitable for stock rebuilds and max-performance applications alike, the only drawback to an MLS gasket is cost. Expect to spend around $200 per pair, but it’s an excellent value considering its durability.
When selecting cylinder head gaskets for your Pontiac, cost and application are among the most important considerations. The best choice is the most affordable gasket that operates reliably in the intended application. Compressed thickness is also important because it has a direct effect on static compression ratio. Each .010-inch difference of head gasket thickness alters the static compression ratio by about .15:1 on a typical 467-ci Pontiac. Certain cylinder head gaskets are also reusable. Assuming they are not stuck to the block and do not tear during disassembly, Fel-Pro and Cometic gaskets can be reused with the same block and cylinder heads at least a few times.
The most import aspect of head gasket choice is the materials it is used with. Aluminum expands about twice as much as cast iron when exposed to the same heat level. A bimetal engine, or one that uses an iron block and aluminum cylinder heads, can literally scrub a head gasket apart as it reaches normal operating temperature if the opposing surfaces have a machining finish that’s too rough. That scrubbing can eventually lead to gasket failure. Pontiac’s original head gasket was very forgiving and conformed to most finishes. The stock-type gasket from Butler Performance performs similarly.
Bolt-On Components
There are two components commonly found within the oil pan of a highperformance Pontiac V-8. A windage tray is a baffle that bolts to the main caps or is an integral part of the oil pan. The aeration created within the crankcase as the crankshaft rotates at high RPM is known as “windage.” As oil drains toward the bottom of the engine, it can splash when it reaches the sump. Windage can keep smaller droplets of splashing oil in suspension, which can then collect on the crankshaft and connecting rods, increasing parasitic drag and adversely affecting performance.
Though the mid 1970s, Pontiac used a stamped-steel baffle bolted to the main caps to reduce windage in its V-8. It doubled as a means of retaining the lower dipstick tube within the block. Reusing an original Pontiac baffle can be dicey, however. After years of enduring engine harmonics, the aged sheet metal can fatigue and crack during use unbeknownst to the owner. It can eventually lead to complete baffle failure, which can then cause serious and possibly even catastrophic collateral engine damage.
Pontiac used a stamped-steel baffl e that bolts to the main caps to reduce crankshaft windage. The unit covering four of five main journals is most popular because it was designed for use with the 455 crankshaft and is generally a bit thicker. Years of exposure to engine harmonics can cause fatiguing and cracking. I much prefer the Tomahawk windage tray from Pacific Performance Racing. It’s a stock replacement 4/5 unit that’s lightly modified to improve performance and reliability and installs just like the original.
Canton produces a Pontiac windage tray that uses mesh screen to control oil aeration and improve horsepower. Covering all five journals, it rests on the oil pan rail and is retained by the oil pan and its fasteners. It’s compatible with the stock oil pan and most stroker assemblies. Canton also offers a similar unit that uses stamped louvers in place of the mesh screen.
Milodon offers a unique stamped-steel windage tray for the Pontiac V-8. It requires the use of specific main cap studs which Milodon supplies. While the tray is compatible with the stock Pontiac oil pan and most stroker assemblies, best results occur when combining it with a Milodon oil pan.
A crankshaft scraper reduces parasitic drag by removing oil that gathers on the rotating assembly during normal operation. A steel shim must be uniquely trimmed for each particular application. This unit is available from Ken’s Speed & Machine Shop and is precut for the Pontiac V-8. It requires only minimal trimming to gain sufficient crankshaft and connecting rod clearance.
The aftermarket Tomahawk windage tray is an excellent replacement. A copy of the stock Pontiac unit, it’s constructed of much thicker metal and is improved slightly. With its relatively reasonable cost and ease of installation, I strongly suggest a Tomahawk unit as opposed to reusing any original. Canton and Milodon also produce high-quality windage trays for the Pontiac V-8. The two are uniquely different and, unlike the stock piece, and may better serve a max-performance application. AllPontiac.com also offers its own windage tray for its aftermarket blocks.
A crank scraper is most commonly found within an oil pan of a race enigne. It’s a length of flat metal that’s installed very closely to the crankshaft and connecting rods on the passenger side o f the block, and “scrapes” oil from them during rotation to keep excess oil off the cylinder walls and reduce parasitic drag at high RPM. Installed clearance is generally between .020 and .060 inch depending upon the application. Due to variances in crankshaft counterweight and connecting rod design, a crank scraper will require some type of custom fitting and requires extra preparation to seal properly. Crank scrapers are available from many vendors and sell for less than $50.
Some feel that with a crank scraper, a windage tray serves no purpose. Others elect to run both simply to improve oil control and ensure their Pontiac V-8 is as free of parasitic drag as possible. I believe at least one should be used in any performance engine and see no harm in using both if applicable. Whether together or singly, the reduction of parasitic drag associated with such components can improve high- RPM performance by as much as 5 to 7 hp. Discuss with your engine builder whether any or either is required at your performance level.
Written by Rocky Rotella and Posted with Permission of CarTechBooks
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