Comp thumper cams
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From: Harrisburg Pa
Comp thumper cams
I have 65 with a 327 Was thinking about putting a thumper cam in. Does any one have any experience with these or recommend another to get that Hot Rod & Yesteryears sound
Thanks
Thanks
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From: Ocean Township NJ
Thunpr cams are designed to sound mean, but they don't perform worth a shlt. They have way too much overlap.
Last edited by 65tripleblack; Apr 26, 2015 at 09:46 AM.
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You need to determine what you need. The Thumpr's aren't necessarily bad....just not perfect for everything. They've got an aggressive intake lobe.. and a longer duration exhaust with a tight LSA. Yep..you get overlap...but depending on the size of the cam...the heads and cubes...they can work OK.
I've found that the Crower #350 circle track cam works very well in street 327's and even larger engines with double hump heads. It's got a tight LSA..but idles clean..will rev to the moon...sounds wicked and doesn't hurt parts.
JIM
I've found that the Crower #350 circle track cam works very well in street 327's and even larger engines with double hump heads. It's got a tight LSA..but idles clean..will rev to the moon...sounds wicked and doesn't hurt parts.
JIM
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Too much information to get into real detail, but in summary: thumper type cams get the valves open sooner and hold them open longer. If you already have high compression, this can lead to detonation at various engine speeds. With the valves being open longer, engine vacuum drops. This can pull carburetor power valves open too early, and can cause lack of power brakes if you have them. The 'cool' sound is the result of an engine with poor idle qualities: you will have low power on the bottom end, and it will sting your eyes with the now very rich idle mixture due to the valve opening characteristics. With a bigger cam, you need stiffer rear end gears to get the engine up in the power band sooner. This results in bad highway manners. I have a big 'thumper' cam in my 4 speed tripower '65 GTO. It's been in there since 1981, when I was a 20 year old kid. Yes, it runs like a scalded cat, but it idles terribly and needs race gas to run. Doing it over, I would have gone with a stock camshaft. So, my advice, if you drive the car much on the street, would be to forego the 'thumper' cam.
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From: Central Arkansas
Too much information to get into real detail, but in summary: thumper type cams get the valves open sooner and hold them open longer. If you already have high compression, this can lead to detonation at various engine speeds. With the valves being open longer, engine vacuum drops. This can pull carburetor power valves open too early, and can cause lack of power brakes if you have them. The 'cool' sound is the result of an engine with poor idle qualities: you will have low power on the bottom end, and it will sting your eyes with the now very rich idle mixture due to the valve opening characteristics. With a bigger cam, you need stiffer rear end gears to get the engine up in the power band sooner. This results in bad highway manners. I have a big 'thumper' cam in my 4 speed tripower '65 GTO. It's been in there since 1981, when I was a 20 year old kid. Yes, it runs like a scalded cat, but it idles terribly and needs race gas to run. Doing it over, I would have gone with a stock camshaft. So, my advice, if you drive the car much on the street, would be to forego the 'thumper' cam.
http://www.compcams.com/thumpr/
There may not be a lot of difference. For what it's worth I'm still running one of those old race cams from Cam Dynamics.
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From: Ocean Township NJ
MikeM: As you well know, the OP gave no information for anyone to recommend "another". If the OP simply wants an engine that sounds mean, then my suggestion, here, should be sufficient. I'm surprised you didn't chime in with your super duper 151 cam, or your handy dandy 097 cam.
Last edited by 65tripleblack; Apr 28, 2015 at 09:05 AM.
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If you really have 400 hp, the exhaust certainly won't sound like a 1953 straight 8 Buick. So, what's up with the engine you have in the car now? Or was the 400 hp a typo?
Last edited by MikeM; Apr 28, 2015 at 10:17 AM.
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Dan, I was refering to generic old school high performance cams. I looked in the Summit catalog and did indeed find the "THUMPR" cams by Comp Cams. 'intake and exhaust tailored to maximize the rough idle sound.." Kind of sounds to me like sticking cards in the spokes of your bicycle.
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I have wondered that since the popularity of cars that are entered in competitions to see how high they can bounce the front end off the ground using hydraulics, and seeing cars that look suspiciously like 1880 Conestoga wagons regarding wheels.
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Always wondered why some people's only criteria for a performance cam is what it sounds like at idle; must be the result of cam grinders marketing their product based on what they sound like at idle. 
