Tom Wilson
April 1, 2003

Horse Sense:
Chuck Jenckes has exercised his engineering talents at several companies, including the major OEMs in Detroit, Trick Flow, and-now, through his consulting business-Demon Carburetion. Always in demand, Chuck says he lives "half the time in Charlotte, half the time in Atlanta, and in Philly with my wife." Testing the larger Speed Demon carburetor required more oomph from the engine

We've all bought parts from companies that we later learned did their research and development on the public. It's not a pretty experience, and so it was great to be invited to a dyno test being held by a manufacturer just to make sure what it was selling was working.

The manufacturer was Demon Carburetion, which was sending well-known engine engineer Chuck Jenckes to conduct the examination. The dyno facility was our usual test haunt at Westech, with main man John Baechtel on the Superflow's throttle lever. Even the test engine was familiar, being our own 302 short-block. It was run in two configurations: stock, and hopped up with a cam, heads, and larger intake. The idea was to check both the street-oriented Road Demon carburetors for stock or mild small-blocks and the Speed Demon for more seriously modified engines.

Specifically, Demon wanted to check the jetting and other variables in the carburetors it is shipping these days. Demon has a wet flow bench at Barry Grant which, combined with years of experience, gives an excellent idea of what sort of jetting that carburetor would want, but still, it's smart to check on an engine dyno.

To represent the bolt-on, stock engine crowd, our stock short-block was dressed with a stock 5.0 H.O. cam and standard-issue E7TE cylinder heads. This includes stock pistons, even a stock oil pump, pan-everything. For dyno duty, the usual set of Hedman 1-5/8-inch long-tube headers were fitted, along with an Edelbrock Performer RPM intake manifold. The carburetor was a BG 525 Road Demon.

As usual, the ignition was supplied by an MSD 6 box, with the timing ending up at 35 degrees after dialing it in. No alternator was fitted, and the water pump belt was set extremely loose. The fuel used was 91-octane Union 76 pump gas, supplied by Union in 55-gallon drums. The gasoline is the same good stuff sold from retail pumps, but having it on hand in large supply saves the monkey motion of running to the local service station to fill cans.

Testing the larger Speed Demon carburetor required more oomph from the engine. Thus the camshaft was switched to a Comp Cams 274 Extreme Energy unit, which gives 224/232 degrees of duration at 0.050 inch valve lift, and 0.555 inch of intake valve lift and 0.565 inch of exhaust valve lift. That's all on 110-degree centers. This is a healthy, workable cam that could get by on the street for the enthusiast, yet make a ton of steam in the midrange and top end.