8. The extensive CNC port work is evident in this shot of the bowl and valve guide. These
As mentioned, our 327 featured domed pistons designed to produce a static compression ratio of 11.0:1. For our build we took full advantage of the elevated compression, but know that the heads, cam and intake package described here work equally well on any low-compression 327-equipped with flat-top pistons. The pistons will require valve reliefs to work with the Comp solid lifter cam.
With a healthy short-block at our disposal, we set off to improve the power output by making changes to those components most responsible for power production, namely the heads, can and intake. As good as the factory components were back in the day, the new stuff is so much better. Off came the L76 heads, cam and intake, replaced by components from Dart, Comp Cams and Procomp Electronics. The key to the success of any build up is to make sure the components were all designed to produce power in the same rpm range. Only working together will they optimize power production. Miss with just one component and the combination will suffer.
We started off with the cylinder heads. Compared to modern heads, the original fuelie heads were both down on flow and up on weight. Chevy never successfully offered aluminum heads on any of the small-block motors back in the day, but they are certainly the hot ticket for performance now. Our heads came from Dart and where the stock heads had trouble exceeding 210 cfm on the flow bench, the Dart Pro 1 heads flowed 100 cfm more. In fact, the exhaust ports of the Dart heads flow more than the intake on the factory fuelie heads.
What the massive head flow did for our combination was allow us to produce exceptional power without resorting to wild (unstreetable) cam timing. The heads featured full CNC porting, a 2.08/1.60-inch valve package and 66cc combustion chambers to slightly lower the static compression ratio.
In addition to a significant drop in weight and tremendous flow, the aluminum heads also reduced the chance of harmful detonation. Capable of supporting over 600 hp in normally aspirated trim, our relatively mild 327 was not taking full advantage of what they had to offer. These heads were chosen as much for what the 327 might become in the future (think stroker) as its current configuration.
Next on the list was cam timing, and here we actually took a step backward, at least in total duration. In truth, our cam selection from Comp Cams was significantly more powerful than the Duntov 30-30 cam, despite a drop in duration at 0.050. Though hydraulic roller cams are all the rage, in keeping with the old-school nature of the 327, we stuck with a solid flat-tappet grind. Compared to the 254 degrees of duration offered by the Duntov cam, the still healthy 236/242-degrees offered by the Xtreme Energy grind seems tame, but there is much more to cam than simple numbers. The Comp cam also offered a 0.501/0.510 lift split, a 110-degree LSA and a recommended lash adjustment of 0.016.
9. The exhaust flow was equally impressive. The 85cc exhaust ports actually flowed more th
10. Comp Cams also supplied a set of 1.5 ratio High Tech roller rockers for our build. We
11. To illustrate the differences in induction system, we tested a pair of intakes on the
12. Designed to optimize power production higher in the rev range, we also included this
13. Fuel was supplied by a Holley 950 HP carburetor. Likely a tad oversized for this appli
14. MSD supplied the ignition system for our build up, including this billet distributor,