Anyone running a thumper cam in a SBC. I'm wondering what kind of vacuum you are pulling at idle. I know with vacuum boost brakes you need to run a can...
Found a discussion of this very thing here http://www.hotrodders.com/forum/carburetor-mods-thumper-cam-140866.html
Dual plane manifold and a vacuum canister can boost vacuum. Many variables to vacuum. I like the thumper, sounds good, very drive-able, and makes more power then stock. Like a good sounding RV cam.
Back when the cam was new they didn't go by lobe separation angle [1976] but I can tell you 242° @ .050, 310° advertised [.006 lift?] Crane H310, at least is what I remember, can't find the cam card or the old catalog to save my memory.........
Yep, got this response last time I mentioned that I run a Big Mutha Thumpr. Run one in a Ford 302, but have never pulled vacuum to see what it was.
Well I had the Thumpr in there couldn't get any more then 5" of vacuum. Totally eratic idle. 350 30 over dual plane performer intake, 600 summit carb , hookers HEI dizzy. Tryed everything I could think of, put a 3.5 power valve in the carb. All kinds of different timing. Tryed a vacuum can didn't see any difference. Plan english the cam sucks. No low end torque. So I am in the middle of pulling it out. Ordered a Howard cam thru Summit. 220 & 230 duration, 470-470 lift and 110 lobe seperation. Should be a hell of a lot better on the street. Thanks for the feed back.
Two things I would address for the erratic idle..Distributor & Carb but I still wouldn't expect much more than 8" of vacuum, just a smooth, lopy idle..
IIRC, there are two different Thumpr cams for the SBC - 279TH7 and 283THR7. Which grind did you have? jack vines
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