After reviewing the cost associated with that, we decided to purchase a set of new aluminum heads from Pro Comp. The Pro Comp castings offered 190 cc intake ports, 70 cc exhaust ports and a 2.02/1.60 valve combination.
The big news was of course the aluminum construction (less weight than our iron factory heads) and the significant increase in port flow, not to mention the new valves, seals and a fresh valve job.
Where the stock GM L98 heads struggled to reach 200 cfm, the Pro Comp heads flowed nearly 250 cfm on the intake and 190 cfm on the exhaust side. These flow numbers offered by Pro Comp can be increased significantly through CNC porting for another $400-$550. Best of all, the 190 cc as-cast aluminum heads can be had (with a little haggling) for less than $600 on eBay. We got ours for $580, but figure on spending $600-$625 for a complete set.
The one potential downside to running the Pro Comp heads was the need for a different pushrod, which further increased our budget. A set of new 7.4-inch pushrods set us back just $29. It was an unnecessary expense to step up to the hardened (chrome moly) pushrods, since we planned to employ the stock guided rockers (eliminating the need for guide plates).
For induction chores, we went to the guys at Professional Products for a single-plane Hurricane manifold. These intakes can be had for as little as $125 bucks via eBay. Having personally run the dyno testing, we can vouch for their performance.
After heads and intake, it was time for the camshaft. Obviously the stock TPI cam was not going to let our motor make anywhere near 400 hp despite the improvements to the induction system. With cost still a major issue, we let our fingers do the walking over the magic keyboard and found some low-buck hydraulic roller cams listed for $139. During our search, we found an honest-to-goodness Comp Xtreme Energy Cam listed on eBay for a reasonable $159. Though this was more of a one-shot deal, comparable cams (at least in specs if not quality) were available for less, we decided our find was legit.
The Xtreme Energy XR282HR offered a 0.510/0.520 lift split, a 230/236 duration split and a 110-degree lobe separation angle. In our quest to save money (it was after all a hydraulic roller), we simply reused the factory roller lifters.
After the compression and oil pressure test, the wrecking yard wonder was disassembled down to the bare short-block. We installed the new hydraulic roller cam using Lucas Oil assembly lube. Though we had no way of knowing the mileage on the used 350, the timing chain appeared to be in good shape and had minimal slop. Normally we'd change this, but we elected to save the $25-$50 cost of the replacement.
We coated and installed the old lifters then installed the newly machined Pro Comp aluminum cylinder heads. We purchased a complete gasket set for the small-block from Motorville. The gasket set us back just $24.95 and included a pair of new head gaskets.
The heads were installed using the stock head bolts. Next came the longer pushrods and guided rockers along with a set of cast aluminum valve covers (also from Pro Comp). We then installed the new Professional Products single-plane intake, followed by our rebuilt Holley 750 carb. The stock HEI distributor was reused along with the plug wires (ours were in perfect shape after a quick cleaning). The final step was to bolt on a set of 13/4-inch dyno headers (not included in the build up cost) and our Chump Change 350 was ready for some dyno action.
The rings and bearing had long since been acquainted but the same could not be said for the new cam and roller lifters. Given the roller profile, a break-in procedure was not mandatory, but we elected to give all the new components time to get properly acquainted before letting the hammer fly.
The oil pressure looked steady at 55 psi and the motor sounded plenty healthy breathing through the 3-inch dyno exhaust. The initial pulls showed plenty of promise, with Chump Change pumping out more than 400 lb-ft of torque at 4,000 rpm.