Small Block Chevy Intake, Carb, Camshaft Testing - Danger Mouse Part Four

A New Intake, Cam, Carburetor, And Spacer
When we started out building Danger Mouse (DM), we knew that testing it would probably turn out to be the most fun we've had on the dyno in a long time. We were correct. For DM's third test we took the same approach most low-buck hot rodders would in the early stages of searching for the most power for the least dollars. We thought a different intake manifold and carb, along with maybe a new carb spacer and a bigger cam, would be the way to go. The results were outstanding, particularly from the new Edelbrock Performer RPM "Air Gap" intake manifold (PN 7501, $195.95 from Summit Racing) we installed.

The decision to retire the Weiand Action Plus intake manifold we had been running since the original dyno tests was not an easy one. However, our search for a new manifold with a larger intake plenum, and one that would also keep the intake charge cooler, revealed only one candidate. Edelbrock had just what the Doctor ordered in its new "Air Gap" design. With its larger plenum area raised up off the floor of the intake, the Air Gap RPM breathes better while keeping hot oil off the bottom of the plenum, which adds unwanted heat to the fresh incoming charge.

This is not to say that the Weiand manifold was flawed in any fashion. In fact, it made terrific power for its extremely affordable, under $100, price tag (currently $99.95 from Summit Racing), and it boosted our baseline power figures by 17 hp. For a first-timer on a low budget, the Weiand 8004 intake manifold is still a great buy.

Our first test of the day was to install this 750-cfm Speed Demon carb. It improved DM's torque figures slightly.

Our first test of the day was to install this 750-cfm Speed Demon carb. It improved DM's t

Power Recap
Last month in DM's second bash on the dyno, we ended the day with a maximum 356 hp and 413 lb-ft of torque. The average horsepower and torque figures were 292 and 395, respectively (see: Test 8). That was 7 hp and 8 lb-ft more torque than we'd started the day with, not that impressive if you're just looking at peak numbers. However, low-end power was increased with the addition of a new cam last month, but we knew we could do better, even with the stock heads still in place.

So this month we first tried a new Speed Demon double-pumper carb, bolted on the new Edelbrock intake manifold, put a Wilson 1-inch open spacer between the carb and intake, and finally installed the next size larger COMP Cams Xtreme Energy camshaft to see what it'd do. The reward this month was a new max 386 hp and 438 lb-ft of torque (+30 hp and +25 lb-ft), and the new averages were 316 hp/416 lb-ft (+23/+20). Now we've got this 355-cid, stock-headed iron Mouse making almost 390 hp and 440 lb-ft of torque. So far this looks like the best formula for power with the stock heads, particularly since the motor didn't respond too well to the bigger cam.

To keep the Demon cool for all tests we used this insulating carb gasket from Mr. Gasket.

That means that the cylinder head's flow potential is just about maxed out, and we'd either have to go in and start porting or install a new set of performance cylinder heads. We think we'll take the latter option, since it'll probably produce results that you could duplicate in your engine. Keep sending your suggestions in and we'll begin tackling them in the upcoming months.

Test 9: Speed Demon 750 Double-Pumper Carb
Since we were planning an intake manifold test for the next round and the Air Gap intake won't accept a Q-jet carb, we needed to test with a square-flange carb first so we'd see exactly how much the carb or intake would add on its own. Westech had a 750-cfm Demon carb that we borrowed for this test. It worked best with 82/88 jetting. Torque improved a little in the lower-rpm ranges compared to the Q-jet, which surprised us. Peak horsepower didn't increase at all, but peak torque figures increased by 5 lb-ft.

Test 10: Edelbrock Performer Rpm "Air Gap" Manifold
We also "borrowed" this Edelbrock Performer RPM Air Gap (PN 7501) manifold from Westech to see if its larger plenum volume would improve power, even though the engine still had the stock heads and a small cam. It worked fantastically, giving us the largest single power increase of any part so far with 24 more peak ponies and 20 more lb-ft of torque.