Z/28 302 Engine Build and Dyno Test - She's A Spinner

Sporting new AFR cast-aluminum valve covers, here is the high-winding 302 assembled and ready for action. Thanks goes to Westech’s Steve Brule for the long hours spent during assembly.

Sporting new AFR cast-aluminum valve covers, here is the high-winding 302 assembled and re

As much as we highlight the big three power producers, the mill simply would not run without a host of other important components, including proper oiling, ignition and cooling systems. Since elevated engine speeds were in the cards, we stepped up the stock oiling system run previously on the stock 302 to a complete small-block system from Moroso. Moroso supplied not only a new oil pan but an oil pump, pickup and even integrated windage tray for our little Chevy. It is possible to get by with a factory pump, pan and pickup on a stock small-block, but when you go testing the rpm limits of the internal components, you'd better make sure everything is well lubed. The oiling system from Moroso ensured our high-rpm engine always had plenty of oil, while the windage tray helped free up some additional power.

The ignition system included a Pro Comp billet distributor and matching wires feeding an MSD Digitial 7 ignition amplifier. Denso plugs were responsible for eventually lighting the fire. We finished off the 302 for dyno use with an electric water pump from Meziere and a set of Hooker long-tube headers feeding 18-inch collector extensions. Since the motor was run previously, there was no need to run it through a break-in procedure and we filled the Moroso pan with Lucas 5W-30 synthetic oil using a K&N oil filter.

The 302 was run on the engine dyno with a Meziere electric water pump and 1 3/4-inch long tube headers.

The 302 was run on the engine dyno with a Meziere electric water pump and 1 3/4-inch long

With our motor installed on the dyno, all that was necessary was to get everything up to temperature, check for leaks and proceed with the tuning. Initial pulls were made with 35 degrees of total timing but we quickly found out that the combination of the short stroke and high-dome pistons wanted significantly more ignition timing. The power climbed with each successive increase in timing until we reached a total of 41 degrees. Next we dialed in the air/fuel mixture, as the previous runs made to dial in the ignition timing were still a tad on the rich side. After pulling a few jets out, we were finally rewarded with a nice steady air/fuel mixture of 13.0:1 at the power peak.

After dialing in the air/fuel mixture and ignition timing, we tightened up the lash and replaced the conventional oil with Lucas 5W-20 synthetic. Our fine-tuning eventually netted us peak power numbers of 519 hp at 7,400 rpm and an even 400 lb-ft at 6,300 rpm. This compares to 357 hp and 333 lb-ft from the stock 302.

After dialing in the air/fuel mixture and ignition timing, we tightened up the lash and re

Since we were looking to extract every last ounce of power out of the 302, we applied a number of speed secrets to fine tune the combination, including tightening up the lash, swapping a series of carb spacers and even lightweight (5W-20) Lucas synthetic oil. After exhausting all of the tricks in the book, we not only managed to reach our goal of 500 hp, but exceed it by a significant margin with peak power numbers of 519 hp at 7,400 rpm and an even 400 lb-ft of torque at 6,300 rpm. These new power numbers represented gains of 162 hp and 67 lb-ft of torque over our original 302. Making the power numbers even more impressive was the fact that these gains came with no change in the 302 short-block. Now we can't help but wonder what it might take to get this little screamer to 600 hp?

302: Stock vs Modified
This graph represents that power curves from the stock and modified 302 Chevy. What is clearly evident from these curves is that the modifications resulted in not only a sizable hike, but also a serious shift in the torque curve. Where the stock DZ302 produced peak torque at 4,400 rpm, the roller-cammed, AFR-headed motor produced peak torque at 6,300 rpm. The significant shift in the torque curve resulted in a jump in peak power, from 357 hp at 6,700 rpm to 519 hp 7,400 rpm. 500hp 383s are considered powerful combinations, but we managed to exceed that figure do it with eighty less cubic inches. Leather-clad biker chicks need love too!