I have a Thumpr cam in my 68 Corvette. I always have to warm it up to get it to idle, but I knew that going into the install. It's a great cam, comes alive after 2500 rpm !!! 327 4spd
I put one in an OT car, (sbc) I restored for a local lady. She wanted the lumpy sound for car shows but wasn't one to care about actually racing. It had a 4 speed Muncie behind it. Seemed to like a good bit of initial to get the throttle response up. I recurved the dizzy. 14 initial, 36 total in by 3000. Holley 600 with 1 spring stiffer than factory on the vacuum secondaries. FWIW. Here's a video of the sound in the OT ride in case anybody cares to hear one:
I ran the large Hyd. Roller in my Model A Pickup playing around w/ different cams w/ that particular engine at the time........went 10.70's running six-two carbs..........I went onto bigger things afterward..but not too shabby........I did not run it for sound..........I let the compression do the talkin...........Littleman Update.........my bad...I went 10.89 running the Thumper......Had to look it up in my log book........
Bingo- the Poser cam is designed to make an engine that's not "bad" sound like it is, for cruising the drive-ins and boulevards
The Thumpr cam design incorporates a not too high lift with a long duration, with lots of overlap. Toss in a very short LSA and you end up with a cam that performs decent, but sounds way bigger than it is. With the duration, and short LSA there's no way it's ever going to idle well with an automatic, in gear; unless you use a higher stall converter. The better choice would be a Howard's Cams Rattler series camshaft. The Howard's Rattler cams were also designed to be a nice lopey camshaft, but with a wider LSA, and they actually perform much better. Not sure why the Thumpr cams get all the press, and hype, when the Rattler is a much better cam performance, and still sounds great.
The Jalopy Journal
