Q: The 350 Chevy in my Pontiac LeMans needs a new bumpstick, and I’m looking at COMP Cams Extreme Energy XE274-10 camshaft (part #CCA-CL12-246-3). I plan on running a TH-350 transmission with a 3,000 rpm stall speed converter and a 3.42:1 rear end ratio. Plus, the engine has a 10.0:1 compression ratio, and the car has a 26.5 inch-tall tire. Is this cam a good choice for acceleration and cruising power?

Pontiac LeMans
(Image/OnAllCylinders – Gioia Kurpik)

A: The Extreme Energy cam is a good choice for your performance goals, but it’s not going to work well with your rear gear and torque converter combination. The setup you described puts your engine just over 2,600 rpm at 60 miles-per-hour. This is below the advertised stall speed of your converter, and can generate excessive transmission heat at cruising speed. We’d suggest switching to a 3.73:1 gear ratio or a 2,500 rpm stall speed torque converter if you choose this cam.

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This is another in a series of weekly Q&A Mailbag sessions with Summit Racing‘s tech department, in which there are hundreds more. Click here to see them all.

Keywords
camshaft, Monday mailbag, ring-and-pinion gears, torque converter
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Author: Dave Matthews

Dave Matthews was a mechanic for the U.S. Army, a Ford dealership, and served for many years as a fleet mechanic for construction companies. Now a technical content producer at Summit Racing, Dave has spent decades working on everything from military vehicles to high performance race machines.