Re: Thumper cams

I've got one sitting in a box ready to go in the 350 I'm building. I went with it for the sound and it's supposed to be similar to an RV grind which will save me some fuel, that and the noise should annoy my hybrid driving neighbor :evil:

 

"the noise should annoy my hybrid driving neighbor"
lol,thats probably why comp originally built them,lol.

 

I am showing my neighbors some mercy; I got the regular Thumper instead of the Mutha Thumper. The sound clip of that one had me drooling. I'm still trying to get that one into my phone as a ring tone.

 

I think the mutha thumpr sounded mean but I cant find a clip of the big mutha thumpr.

 

mutha thumper

tuning is a beast

 

Total pieces of crap that have so much overlap you can't get a good vacuum signal to the carb to tune it. Many people on here have made the mistake of installing one and wind up removing them pretty quick. Most people I know could care less how your engine sounds, show us how it runs. Just sayin'.

 

muthr thumper

what would be a good hyd roller replacement?

 

All these cams are is the basic "fad" cams. They make a engine lope and sound mean, all bark and no bite. They`re for people who can`t make a regular high performance cam lope. For example, my best friends 350 has a hydraulic roller cam with .215 duration, and it says "slight lopey idle" and this is a single pattern cam. This cam lopes real nicely in gear at idle, however most will install it and it won`t lope. why? It`s all in the tune.

 

like double vision said, all it takes is a lil bit of tune, headers, the exhaust positioning(tuning) , and some of my favorite things for a chevy is a dual exhaust with two cherry bomb glass packs i dont go really fancy like what all these people with the loud mouth set ups, those people annoy me haha, so loud yet they get away with that

 

o and double vision, your buddys cam profile seems to have intrested me, whats the specs on that? Is it chevy?

 

This is the retro fit cam, however, they also have this same cam for OEM roller cam blocks which is what he`s running.
http://www.summitracing.com/parts/CCA-12-420-8/
His combo consists of RHS Vortec heads. With this cam and combo, it has absolutely killer out of the hole torque with 3.42 gears and gets good fuel economy.

 

I once had the comp big mutha thumpr hydraulic roller cam and it does sound very wicked and actually ran well with my engine but I could never get my carb to tune right no matter what I did and I only had about 5 to 6 inches of vacuum and sucked to even drive though town. I changed it out within a couple of months cause I had enough of it. I put in a lunati voodoo cam much smaller and I loved every bit of it and got 12 to 13 inches of vacuum and did not have to do a whole bunch to tune carb and ran very strong still and is much better that way it is now. Those cams have so much overlap to me there are not even worth buying unless its something you don't plan on driving much but they need a lot of stall for auto transmission and locked out timing and to me too much hustle when you can get other style cams which might not lope as much but they sound great none the less and perform way better with the matching setup.
eric

 

I once had the comp big mutha thumpr hydraulic roller cam and it does sound very wicked and actually ran well with my engine but I could never get my carb to tune right no matter what I did and I only had about 5 to 6 inches of vacuum and sucked to even drive though town. I changed it out within a couple of months cause I had enough of it. I put in a lunati voodoo cam much smaller and I loved every bit of it and got 12 to 13 inches of vacuum and did not have to do a whole bunch to tune carb and ran very strong still and is much better that way it is now. Those cams have so much overlap to me there are not even worth buying unless its something you don't plan on driving much but they need a lot of stall for auto transmission and locked out timing and to me too much hustle when you can get other style cams which might not lope as much but they sound great none the less and perform way better with the matching setup.
eric

One more reason why people should be looking at cams that match their application and not because they sound cool.

 

One more reason why people should be looking at cams that match their application and not because they sound cool.

x's 2 say it again lol you cant be any righter :thumbup:

 

This is the retro fit cam, however, they also have this same cam for OEM roller cam blocks which is what he`s running.
http://www.summitracing.com/parts/CCA-12-420-8/
His combo consists of RHS Vortec heads. With this cam and combo, it has absolutely killer out of the hole torque with 3.42 gears and gets good fuel economy.

well this looks part way what im gonna be running, 406, large port vortecs, 10 to 1 CR. Only difference is displacement and the runner size thanks for sharing. I havent looked at this in a mean while, and now its already got me thinking bout this same retrofit cam. Looks like id have a killer torque spec too huh?

 

well this looks part way what im gonna be running, 406, large port vortecs, 10 to 1 CR. Only difference is displacement and the runner size thanks for sharing. I havent looked at this in a mean while, and now its already got me thinking bout this same retrofit cam. Looks like id have a killer torque spec too huh?

I don't know where the DCR would be w/that cam in your engine w/10:1 CR. I think it'll prolly be OK w/premium but I'd be checking to see that it's OK for pump gas. I'd also not want to try to go much smaller on the duration @ 0.050" lift.

 

I don't know where the DCR would be w/that cam in your engine w/10:1 CR. I think it'll prolly be OK w/premium but I'd be checking to see that it's OK for pump gas. I'd also not want to try to go much smaller on the duration @ 0.050" lift.

CompCams 12-420-8 closes the intake at 33.5 degrees ABDC @0.050" tappet lift. KB's DCR calculator puts the DCR at 8.90:1 with 3.750" stroke and 5.700" rod. Using a 6.00" rod puts it at 8.88:1. I suppose you could run premium pump gas if you ran a very tight squish and smoothed everything out in the chamber and piston crown, but as for myself, I would rather use a little more cam and tame down the squeeze a little. With 10.00:1 SCR and a 5.700" rod, a cam that closes the intake at 42 degrees ABDC @0.050" tappet lift would yield a DCR of 8.48:1 and that's probably what I'd do because a DCR of around 8.5 seems just about right to me. I never did like to build anything right up against the wall with no wiggle room. Something like this is what I'd be lookin' at....See the intake close at the bottom of the card....
http://www.cranecams.com/product/cart.php?m=product_detail&p=24188

 

I wasn't sure on the DCR but I'm 100% w/you on not building an engine w/CR right on the edge- there's possibly a few percent gain in power per point of CR, but a bit too much CR can cost huge power if the total timing has to be retarded from best power timing. Or can cost huge $$$ if detonation is allowed to occur under load. Plus who knows what the future holds as far as available gasoline octane goes.

Much better IMO to build in some leeway in the CR for a bad tank of fuel, a parts failure that runs the coolant temp up, etc.

 

id probably wanna run a lil bit bigger Gasket, if the qeunch is good, and the cam you listed, is a super charger cam i didnt think i could use one in a natural aspirated, but i geuss anything can be done with the right stuff. Hmm if i were to step up a lil i might run the 10:1.1 SCR and a lil bigger at .050 it just might be what im looking for? I was also looking at Howards Max Torque retro fit cam kit(i think its a kit),
110325-10
and lunatis bare bones cam set, Dont know the camshaft itself, just the kit (im gonna take a good look at it specificly)
10020LK
im a big newb at camshafts, i dont like and wont like for a while, cause all of em have a catch. and im not really a huge fan of checking em out