The intake manifold runners...
The intake manifold runners were given the same treatment as the heads. The runners were tapered from as-cast, down to the 1205 gasket size, increasing port velocity and efficiency.
With the induction and valvetrain systems in good shape, we didn't want to neglect the bottom end of our mini-mouse. Our good friend Kris Henderson donated a vintage '67 327 block and factory steel crank to the cause. Knowing that we would have a tough time keeping our cam alive, I placed the block upside down in our mill and drilled .059-inch-diameter holes in the main oil galley above each of the cam lobes to spray oil directly on them. We then built sheetmetal trays and fitted them under the cam, so the excess oil would not pour directly on the crank to create excess windage losses. Restrictors in the lifter galleys kept the majority of oil focused on the cam squirters and main and rod bearings, instead of shoving it all to the top end where a high volume is not required. Adding up the areas of the camshaft oil squirters basically put an almost 3/4-inch hole in our oil system. Even with conservative oil bearing clearances helping us out, we were idling with a mere 7-9 psi of oil pressure, and maxing out at 40 psi. In the future, dropping the squirter size to a more reasonable .020-inch would increase pressure significantly, and make the design feasible in a street car. As a method of easily keeping track of running oil pressure, as well as satisfying our curiosity, we measured oil pressure at the standard location on the rear of the block as well as the front of the main oil galley, and found almost a 10-psi drop. This lead to future plans to check oil pressure at the end of the lifter galleys as well.
Once the block was machined, we spent several hours with a rock grinder reshaping the GM crank before chucking it up in the lathe and turning down the counterweights. This acComplished two tasks: First, we were able to reduce air friction through bullnosing the front edge and knife edging the trailing end of the crank. Second, removing mass from further out on the counterweights and concentrating it more toward the center allows the crankshaft to rev quicker. Some dynos may not record improvements in inertia as increased power, but testing on the DTS dyno, as the EMC is contested on, definitely showed a real-world improvement that would be seen at any race track.
Swinging on the rod journals was a set of Eagle Specialties Superlight connecting rods with ARP 2000 bolts keeping the caps securely in place. In line with our plans to reduce rotating and reciprocating mass, we pressed out the factory wrist pin bushings, machined a set for flyweight .866-inch-diameter wrist pins, pressed them in, and honed them to fit. Ross made sure the custom pistons they designed would work with the combination, and they were sealed up with Total Seal gapless rings.
Using big pushrods has consequences....
Using big pushrods has consequences. We had to clearance the pushrod holes so there was no interference there. A minimum of .010 inch is recommended, as the head can act as a sort of second pushrod guide, and anything more than that is wasted time with a grinder.
Rules changes for the '08 EMC restricted the dimensions of the oil pan to no wider than the factory pan rails, and no deeper than 12 inches from the crank centerline. Taking advantage anywhere we could, we called up Kevco Oil Pans and had them make us a piece within those specs. It included a windage screen as well as a baffle underneath it. A crank scraper was also quickly fabbed up to help out. The pan housed a Melling M-Select high-volume oil pump that we put to the test.
Once the bulk of the engine was laid out, a significant portion of our time was spent tuning it to wring out whatever we could from the little mouse. Patrick at Pro Systems carburetors built us a 4150-style carb that was as pretty as it was functional. It responded well to jet and air bleed changes in a manner that was predictable and repeatable. Not all carbs share that trait. The carb used annular boosters that tend to reduce total airflow, but increase response and fuel atomization at lower rpm. The carb was perched atop a Comp Cams phenolic 1-inch open carb spacer. The phenolic plastic reduces heat transfer from the intake to the carb, and is lightweight to boot.