All car guys know that the soul of an automobile is derived not only from the name badge and styling, but also the motor that powers it. Long-time Pontiac lovers have a deep understanding of what makes a Pontiac a Pontiac. Aside from the superior styling and engineering, it's the powerplant that seals the deal. As we have learned over the years, Pontiac performance buffs also exhibit a certain affinity for big-cubed engines in their race cars, street cars, and probably lawn mowers if given the opportunity.
Chevy has 502ci crate motors just a phone call away. Pontiac doesn't. However, good old Pontiac perseverance has kept the big-cube quest rolling forward as 400-455 blocks have been worked up to 474 cubic inches--some custom jobs even further--with the aid of stroker cranks and over-bores. Cool and fast? Sure! But 500-plus cubes reasonably affordable? Well, no.
With the advent of the Indian Adventures' Chief Many Horses Siamese bore engine block (IA) a few years back, there was reason for celebration because Pontiac racers and big-cube fans finally had a block that could handle serious bore and stroke increases, was much stronger than stock, and would accept traditional Pontiac engine parts. Yes, there were some issues with the blocks that go hand in hand with a fledgling project. Nevertheless, Pontiac racers made them work and achieved power numbers that stock Pontiac blocks could only dream of.
Now thanks to Allpontiac.com and its owners Frank Gostyla and Bob Cacciotti, there is the IA II block--which is a new and improved IA block. It promises consistent quality, a reasonable price at $2,995 plus the current alloy surcharge, and many upgrades about which you will soon read.
The IA II block used for this story is actually a prototype. Frank and Bob wanted to put their fresh casting to the test before they unleashed it on the public. So they placed prototypes in the hands of a select few engine builders to flush out any issues that should be attended to prior to casting blocks for retail sale.
Paul Spotts of Spotts Performance was one of the engine builders who was tapped for the project. His would be a street engine using a prototype IA II block destined for Frank's '71 Firebird. Spotts decided that this would offer a great opportunity to create a 500-plus-ci "crate motor" for street/strip Pontiacs. So HPP documented the buildup with Spotts Performance and Allpontiac.com for the first, of what Paul hopes will be many, Spotts Performance crate 505 engines.
This story will be broken into two parts: the first covering the engine-block details and the bottom-end assembly, and the second will cover the top-end build and the dyno testing.
About the IA II Block
Using the original IA block tooling, Dennis Russ of Roush Industries was brought onboard to retool and recast the blocks, ensuring that three issues of the first run IA blocks were addressed: total sealing, ease of adaptability, and block strength. More importantly, if it was to be considered a Pontiac block, the IA II had to accommodate traditional Pontiac parts and performance aftermarket Pontiac parts.
The IA II utilizes a standard Pontiac five-bolt motor mount pattern, so it will fit in an earlier chassis with two-bolt mounts or a later chassis with three-bolt mounts. Standard deck IA II blocks have cylinder bores of 4.245 inches. Included are billet steel four-bolt main caps, and ARP main studs and outer ARP cap bolts. The block accommodates a Pontiac factory-sized 3-inch main crank (326 to 400-cid or aftermarket strokers) or can be provided on special order with 3.25-inch main saddles for 421- to 455-cid or aftermarket stroker crankshafts.
Nothing beats big cubes, so engine displacements over 540 cubic inches can be achieved with the Siamesed-cylinder bores, allowing up to 4.400-inch bores (and that is just the standard deck!). Future available tall deck blocks allow even more cubes to be created.
Fluid Management
Since a motor is useless if it can't contain its own fluids, wider pan rails not only add strength, but provide better oil pan gasket sealing and retention. Improved and 20-percent enlarged oil passages increase durability and reduce the chances of oil starvation at the front main bearing. To further limit restrictions, the oil pump passages have corner plugs at 90-degree turns to "elbow" the flow. Threaded oil filter passages provide easy remote filter mounting.
Engine-block modifications were made to accommodate screw-in freeze plugs. Additionally, cooling passages were enlarged by 10 percent around the cylinders and redesigned to allow for even cooling of the block and heads.
Unlike the prototype block Paul was building/testing, decks are cast with the block-to-head coolant crossover passages blocked off. This allows the racer the option to either gasket-match (drill) the coolant openings or dry deck. In addition, the IA II has 1/2-inch NPT tapped holes in the back of the block for passing water back to the rear of each head, so you now can direct the water back to the crossover and then to the radiator for improved cooling.
IA II Strength
The most important aspect of any high-powered engine is strength. While original Pontiacs depended upon heavy nickel-content castings, the IA II depends upon ingenious casting designs and a special blend of cast iron for its strength. Everywhere one looks on this block, they will find bulk in its design. Even at a 4.375-inch bore, cylinders still maintain a 0.200-inch-plus wall thickness for unprecedented cylinder integrity.
All IA II blocks come standard with steel main caps featuring a splayed four-bolt design on the three center mains, which add rigidity. Though not on the prototype block, the production block main caps will be registered in the block like many other high-end racing blocks to add rigidity and to better keep the caps properly aligned. Main webs have been thickened to the maximum that space will allow, and the bottom of the block is solid all the way to the bend above the oil pan rail (again, to increase rigidity).
The cam tunnel now has enough meat to be hogged out to big-block Ford size for extremely radical roller cam profiles. Lifter bore breakage in the factory blocks has been thwarted in the IA II by casting the lifter valley as a solid piece and then drilling oil return holes into it. Lifter bore feed holes are already tapped for the use of restrictors for solid cams.
Recognizing that retaining compression is an issue in all high-compression motors, thicker-than-stock deck surfaces provide added strength and aid in cylinder-head sealing. Head bolt bosses are tied deep into the cylinder and exterior block walls to aid in compression retention.
Adaptability
The original IA block dictated that a dual-bellhousing bolt pattern was cast in for both Pontiac and "corporate" housings and transmissions. And, of course, the new IA II kept that design.
Lifter bores are deeper now to allow use of "corporate" lifters if you're in a pinch. The bottoms of the cylinders are notched to clear strokes up to 4.75 inches with no problem. But for the true torque titans, a 5.00-inch stroke is possible with steel rods and some grinding; aluminum rods are limited to a 4.500-inch stroke. And mindful of the little things, boost fiends will welcome a threaded front external oil passage for lubricating superchargers or turbos.
Options
Allpontiac.com is currently developing four other variations of the IA II--the tall deck iron block, both the tall and standard deck blocks in aluminum, and a standard deck block made from compacted graphite with 3.00-inch mains. The tall deck iron block will feature an 11.00-inch deck height, .386-inch raised cam centerline for added stroke clearance, and 3.00-inch mains.
Allpontiac.com will also provide a few custom touches such as a bore-size increase ($100), 3.25-inch mains ($190), rollerized needle cam-bearings ($350), and bronze lifter bushings ($350).
The Buildup
The scope of this tech article is not to show you how to build an engine step by step, but simply to expose the secrets of the IA II block--what went into its maiden buildup and what's inside Spotts Performance's new 505 crate motor.
According to Paul, "This was not a 'build a gazillion horsepower' project. Rather it was an exercise to learn about the features and idiosyncrasies of the IA II block and building a street 505-cube engine that has vacuum for power brakes and uses a true street type cam. It didn't make huge horsepower numbers but did deliver on torque. It idles like a mild engine but can still put a well-prepped street car into the 10s."
For a sneak peak at the horsepower and torque figures, check out the Engine Buildup Worksheet. And for further details of this particular prototype build up, visit www.spottsperformance.com.
Paul Spotts will be offering 505-cid IA II crate motors similar to this one by the time you read this. As this was a prototype block, there are slight visual differences in the production blocks that have already shipped. Additionally, certain modifications described in this article will not be necessary with production IA II blocks.
