Gasser HotRod Forums banner

Comp cams thumper cam?

3022 Views 3 Replies 3 Participants Last post by  1937Austin
Anybody use one of these in a smallbock Chevy? My buddy just bought one that I put in his '56 Chev gasser with a 350/th350. We finished the engine swap, with conversion to side mounts and tranny crossmember today, and fired it for the first time. I was surprised how radical the cam sounds. Specs don't seem to indicate it would be, but it sure has a lumpy idle, and grabs rpm's pretty fast!
1 - 4 of 4 Posts
IMO, and those of a couple reputable engine builders I do some business with, nothing but a "poser" cam. The rumpity rump comes from the timing of the valve opening and closing and the duration... I usually go with a custom grind that the cam company's tech guys suggest. I'm more concerned with the acutual performance of the car then the sound of the engine. Being fast and sounding fast is seldome the same cam. Guess it all depends on what your priorities are for the build!!!!!

Another item of interest that most all the engine builders are saying now is to run a roller cam, hydraulic roller for the street, mechanical roller for racing, as the oil we get now doesn't have the right chemical compisition of ZDDP to make a flat tappet cam last. Seen lots of flat tappets go bad in the last few years, I run rollers in everything now with no problems. Performance is a lot better with the faster and steeper ramp rates with the rollers, too.
I believe the thumpers were purposely designed to give the heavy rump/rump at the cost of all out performance. Your description was perfect---a poser cam---. It'd be a lot cheaper to just pull a plug. Hey, that would be a great idea for a new product. A rev limiter type little black box that would cut out one cylinder successively in the firing order for each revolution. Do that at the car shows while your puttin' thru the grounds and then kick it back in for cruising home. Bet we could sell a million of 'em. Mark L
Specs on the cam seem to indicate just that. It's got lots of duration (279/297)to get the lumpy idle, and OK lift, but not really high.(479/465) with a small separation os only 107 degrees. Sure not a racing cam, but performance wise it seems to be great off the line with good low end power, but pretty much all done around 6,000-6,500 rpm. Yeah a poser cam, but that's what the guy wanted for his street only gasser '56.
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.