Small-Block Top-End Swap - Big Power For Little Cash

Swapping Top-End Parts to Make 523 Horses

Bob Mehlhoff Dec 1, 2006 0 Comment(s)

TEST ONE

For our baseline test we achieved the highest torque of the day, 490 lb-ft at 4,400 rpm. This is largely due to three reasons: The XE274H camshaft features less duration, the Air Gap intake is a dual-plane manifold, which helps produce a stronger intake signal, and the 750-cfm carburetor is comparatively smaller than the larger 850 we later used.

*750 Mighty Demon carburetor
*Edelbrock Performer RPM Air Gap
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 274 cam w/1.52:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78
*Timing: 37 total

TEST TWO

For this test we switched intakes from the Performer RPM Air Gap (dual-plane) to the Victor Jr. (single-plane) and recorded improved horsepower at a 200 higher engine rpm (488 hp at 5,900 rpm, compared with Test 1's 471 hp at 5,700 rpm). The peak torque number dropped to 475 lb-ft but at a slightly higher rpm.

*750 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator Cylinder Heads
*Comp Cams Xtreme Energy 274 cam w/1.52:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78

TEST THREE

After a camshaft change to a bigger XE284H and 1.6:1 roller rockers we moved the horsepower number up considerably to 518. Peak torque stayed flat but was reached at a higher 5,200 rpm.

*750 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78

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