All other parts were the same as the previous test including the 750cfm carb and Magnum 1.5:1 ratio rocker arms. The mid-range Thumpr camshaft was tested next – part number 287T. In this case, we were pleased and made almost no changes to the carburetor aside from adjusting the idle. Holley’s are generally known for being ready-to-go right from the box. Westech’s “Magic-Man” Steve Brule installed the new Holley 750cfm carburetor on top of our small-block mule. For each configuration several tuning tests were completed – with the three best pulls averaged together to create a fair representation of the engine’s power and torque. The dyno test was run through a range of 2,600 to 6,000 rpm. To that mix we added one set of RHS as-cast, assembled aluminum cylinder heads (180cc runner volume, 64cc chambers, angle plug design). The base engine was a time-tested 350cid 290 horsepower small block GM crate engine featuring a Weiand Air Strike intake manifold, 650cfm Holley carb, Hedman 1 ¾-inch primary tube headers, Magnum mufflers with 18-inch collector extensions and an HEI distributor system. The following tests were run with the COMP Cams new Flat tappet Thumpr camshaft on the Westech dyno over three days in late December. Under the guidance of Steve Brule at the Westech Performance dyno facility, we subjected our dyno-mule to a severe list of duties, including a cylinder head swap from RHS, a Holley 750 cfm carburetor and multiple camshafts. If there is one area to note, it is the engine vacuum readings from the Thumpr-equipped engines. The results of our testing prove the mettle of the Thumpr cams, great power and torque, neither component compromised in the quest for great performance sound.

To test the real power found with these camshafts we enlisted the folks at Westech Performance to take the new flat tappet camshafts and test them head to head with the stock 350cid, 290 horsepower GM crate engine and an Xtreme Energy COMP Cams cam with similar performance specifications to these Thumpr Camshafts (actually it fits between the middle and largest camshaft in the line). And the public reaction has been overwhelmingly positive. It’s pretty simple science and while logic would have you believe that power is lost due to this overlap, our results have shown the performance is actually up over similar camshafts due to COMP Cams innovative lobe designs. This creates more overlap between exhaust and intake events and more “cool” performance sound. The Thumpr line delivers true high performance engine sound by “tightening” the lobe separation angle of the camshaft. The basic science behind the Thumpr Cams is not a new one.

Comp cam 350 sbc