Richard Holdener
November 1, 2009
400M-Stock vs Cam Research/RPM vs Cam Research/CHI
This graph illustrates the difference between the baseline run and the two intakes equipped with the custom Cleveland cam from Cam Research. As with the smaller cam, the dual-plane intake offered better low-speed power (up to 4,300 rpm) but fell off thereafter. Equipped with the dual-plane and new cam, the 400M produced 528 hp and 525 lb-ft of torque. After installation of the CHI intake, the peak power numbers jumped to 568 hp and 542 lb-ft of torque. Those are big numbers from a 9.5:1 400M boat anchor.

With our first upgrade a success, we decided to install the custom roller cam from Cam Research. The Cam Research profile increased both the lift and duration figures compared to the Street Roller cam from Crower. The Cam Research cam offered 0.726 lift and dual-pattern duration figures of 250/254 degrees at 0.050. The cam also featured a tight lobe separation angle of 106 degrees. Looking just at the specs, you might be tempted to dismiss the cam as excessive, but just check out the power gains and you'll realize that there is much more to the cam grind than simple lift and duration figures. While we'd expect additional power gains from the increased duration, what really surprised us was that the Cam Research profile improved the power output everywhere, from 3,000 rpm to 6,500 rpm.

We bolted the Edelbrock RPM Air Gap intake back on, along with the 750 Holley, and with the Cam Research stick stuffed in, the peak numbers jumped from 489 hp and 502 lb-ft of torque with the Crower cam, to 519 hp and 519 lb-ft of torque. These peak numbers were further increased to 528 hp and 525 lb-ft of torque with the installation of a 1,000-cfm Holley carb (to replace the 750 Street).

The final test was to run the new cam with the CHI single-plane intake, and boy, did this combination work well. How does 568 hp and 542 lb-ft of torque sound? Remember this was all with a static compression ratio of just 9.5:1. I guess the aluminum-headed, tall-deck, stroker Clevelands will be getting a little more respect.

Airflow Data-Pro Comp Cleveland Heads:
IN/EXIN/EX
LiftProDr. J's
0.05031/2240/28
0.{{{100}}}66/4678/58
0.{{{200}}}127/95149/99
0.{{{300}}}183/129217/135
0.400225/161273/169
0.500263/182318/209
0.{{{600}}}291/207335/231
0.700314/219343/247
0.800325/228351/253