Some people are never satisfied; ordinary just won't do. For most, simply owning a nice '67 GTO would be great. Getting to drive around in a fully restored one would be a dream come true. Not so for Jeff Hutchens of Springfield, Missouri. If it looks fast, it had better be fast.
Following a lead from a previous MCR customer, Jeff looked up the guys at Muscle Car Restorations (MCR) in Chippewa Falls, Wisconsin. MCR is known for restoration work, but it's also no stranger to building ground-up race cars. Jeff owned a '67 in high school and he didn't want to mess with that classic GTO look, but he also had to have the state-of-the-art performance to run with the high-dollar exotics. We'll begin with the powerplant and get to the chassis in later issues.
The IA II block is very beefy...
The IA II block is very beefy and is claimed to be good for up to 3,000 hp. This 3.00-inch main-block is made from ASTM-class cast iron and has Siamesed cylinder bores, 4-bolt mains, thicker main webs and deck surfaces, and wider pan rails than a stock Pontiac block. It also has threaded freeze plugs, a redesigned cooling system, and improved oiling. With a 5-bolt motor-mount pattern, it will fit in any Pontiac, and it has bellhousing bolt patterns to accept BOP and Chevy transmissions.
How much performance does Jeff desire? How about a twin-turbo pump-gas IA II engine in excess of 500 ci? Sure this combo will produce lots of power, but it has to be smooth, controllable power that uses real pump gas from any corner station. It also has to be new-car-with-a-warranty reliable.
To that end, MCR told Butler Performance the customer's desires; Butler scienced out the combination and supplied many of the parts to build it. Wheeler Dyno Service performed the assembly, and MCR fabricated the turbo exhaust.
An IA II iron-block provides a solid foundation; this one received a 4.350-inch bore and will run a 4.250-inch-stroke forged crank. It could have been built bigger-4.400 x 4.75 is the absolute max-but by leaving a few cubes on the table and building the engine a little "under square," it will rev quicker than a "maximum-inch" beast and retain thick walls to better contain cylinder pressure. Besides, 505 ci under boost is more than enough to test Jeff's nerve.
The forged 4.250-inch stroke crank is spun by a set of Ross custom-forged pistons by way of Scat 6.700-inch forged rods and Ferrea pins. The bearings are Sealed Power, and Jeff Fiala at Wheeler, who assembled the engine, custom-filed the Total Seal classic rings. A custom street, hydraulic roller from Comp Cams with 258/248-degrees of duration at 0.050, 0.541/0.541 lift, a 111-degree centerline, and a 115-degree LSA was chosen for this engine.
A cam that works well with a normally-aspirated combination won't work as well on a turbo engine because too much overlap will blow boost out the exhaust. The last thing Jeff wants is a peaky power curve. Besides, a proper cam will improve exhaust gas velocity, which will help the turbos to spool up more quickly. Since there are two turbos, they'll still be able to push the top end into the "too much" category. An added benefit is a relatively smooth idle that will allow easy around-town cruising, just hinting at what's inside.
It comes with a dry deck,...
It comes with a dry deck, so Jeff Fiala of Wheeler Dyno Service drilled holes for the water passages using the head gasket as a template.
Jeff dressed the area of the...
Jeff dressed the area of the main-bearing and cam-bearing oil passages, and deepened the notch between them.
Jeff drilled oil drain holes...
Jeff drilled oil drain holes in the lifter valley since this block didn't have them. All current IA II blocks already have this feature. The Comp Cams hydraulic roller lifters will drop in without modifications to the block.
During preassembly, Jeff installed...
During preassembly, Jeff installed the Comp hydraulic roller cam to ensure it rotated freely and to check piston-to-valve clearance.
For final assembly, Jeff prefers...
For final assembly, Jeff prefers 60W motor oil for pre-lube; he used the Viton rear main seal from BOP Engineering. The block and cap halves were staggered, as shown, to help prevent leaks.
The main caps are steel and...
The main caps are steel and the center three have a splayed four-bolt pattern for extra rigidity. ARP studs are used, except for the outboard holes for the splayed caps. Jeff used moly lube on the threads and under the nut/bolt face as well, to insure accurate torque. The rear main gets 120 ft-lbs while the centers receive 100 and the outer bolts get 85.
Full-floating 0.990-inch Ferrea...
Full-floating 0.990-inch Ferrea pins connect the custom Ross forged pistons to the Scat 6.700-inch high-tensile 4340 forged H-beam rods, which feature a 2.20-inch diameter big end to fit the Chevy-sized big-block crank journal. For this zero-deck engine, the compression ratio of 7.96:1 results from a 49cc dish in the pistons, 90cc chamber E-heads, and the volume of the Cometic head gasket.
Here is the bottom end prior...
Here is the bottom end prior to installation of the Milodon windage tray and Melling high-volume oil pump.
Jeff installed the cam straight...
Jeff installed the cam straight up and verified it with the degree wheel. As you can see on the deck, this engine is not o-ringed despite the boost potential of the twin turbos. "The Cometic MLS (multilayer steel) head gaskets will handle this level of boost and seal water in a street pressurized system much better than a copper gasket with O-rings," Jeff says.