[Mechanic No. 4]

Anyone have any experience with Comp. Cams Thumper line of cams? Heard they were a "for the cool sound" cam only, but actually were a very good street cam.
Any input? Thanks in advance!

[guccieng]

they only recently started making them for ponchos, and i haven't heard of anyone trying it yet.

[Formulas]

Some reviews are less than stellar but most reviews i have seen are brand X engines..
Now... in theory for Pontiac they may fair better in a street strip situation for us because the thumper cam series has conservative lift figures lazy lobes with alot of overlap..compared to the faster ramp flat tappet cams of late that seem not to work so well..

Would this be the hot ticket for max HP. on a large port CSA Pontiac head ?
Most likely not.. but for the average head flow challenged Pontiac this particular cam series may work..

I have been eyeballing them myself for a 440 i am slowly putting together.. i have 72 cc E`heads ( not exactly flow challenged ), Aries 2 valve relief pistons 4340 forged rods and a fresh block.. kinda looking around for a forged 4 inch stroke crank at the moment

[i82much]

I think they have tight lobe seps.

[Ollie]

Originally Posted by Mechanic No. 4

Anyone have any experience with Comp. Cams Thumper line of cams? Heard they were a "for the cool sound" cam only, but actually were a very good street cam.
Any input? Thanks in advance!

If your gon'a talk the talk, you better be able to walk the walk.

[Z Code 400]

Think about this...

The 'Thumper' line is advertised as having lots of overlap for that racey sound at idle. Then, in the same sentence, Comp says the grinds are almost identical to their 24 hour endurance grinds.

I would avoid the 'marketing ploy' line of camshafts and stick with what is known to work in these engines...Robert

[DAVE RIBEIRO]

Z Code 400,

You are right on , poor choice of words by Marketing people.... But they have been making good race cams for Pontaics for years in Stock & Super/Stock classes... My cam sounds like a street cam and runs very well... I tried Crane, Bullet and Isky cams and have always come back to Comp .Cams... Real good people to deal with and very good quality... Hope this helps... Dave...1033/stock(RV-455)

[screamingchief]

In spite of the marketing dreck,odds are these lobes by their own merits are likely no worse than any other lobes on the market,but by the same token their not likely the best choice for max output applications either.

It's how one takes those basic lobes and applys them to a given application that makes or breaks them.

I'm sure if those thumpr cams were used in a combo that is in need of a cam like those cams are ground,they would probably give pretty good results.

So you ask what combo would like a cam like those,hmmm,now that's a good queston?

I'd hafta say a low compression engine with a really good exhaust system behind it.

With the tight LSA,the last thing you would wanna do is put a restrictive exhaust system behind it.

And with Comps recommended ICL (102° ICL for a 107° LSA),I would'nt wanna use a cam like that in a high compression engine,though that sorta ICL would likely be fine for an 8.5:1 engine.

I also dont think I'd use it in a overly heavy car either,a light car with good gears and a decent converter would be best.

I can envision a combo that could use something like that,but there's just not that many pontiacs out there that are being built like that right now.



Bret P.

[1974formula]

Any up-dates on this cam ? ....no Pontiac guys trying them ?
The Big mutha Thumper (and mutha thumper) are on eBay with the lifters for $749.00...not bad.

Mutha Thumper;
..2000-5800 rpm, needs 9.1:1 comp and 2400 rpm stall, lower gearing, headers.
adv duration- int 291/exh 311
@ .050 235/249
GVL with 1.5 .558"/.542" (the web site has the 1.72 rocker for this lift, that's a typo, they replied to my question)
LSA 107


Big Mutha Thumper;
2300-6100 rpm, 9.5:1 comp, 2800+ stall, low gears, headers, intake.
adv duration 299/319
@.050" 243/257
GVL with 1.5 .570"/.554 (again, the 1.7 rocker on web ad was a typo)
LSA 107

I'm looking at these wondering how they would work in a 406 with 9.6:1 ported (240-250cfm) cast heads, headers, Tomahawk, 750 or 800 Q-jet, 3000 stall, 3.73 gears and 3600-3700 lb car, would I get the 450-460 ++ HP I want ?

I need a desktop dyno

[PONTIAC DUDE]

I have installed a few in SBC's. Therottle response was good. But they were rather tame for the duration figures and didn't notice that big a ............... Thump.

[Cliff R]

"Now... in theory for Pontiac they may fair better in a street strip situation for us because the thumper cam series has conservative lift figures lazy lobes with alot of overlap..compared to the faster ramp flat tappet cams of late that seem not to work so well.."

It's not the fast ramps that get some of these cams into troubles. Ultradyne has been using fast ramp technology successfully for decades. It's the opening and closing velocity that can/will cause troubles. Seating the valves too quickly can cause them to "bounce", and really quick opening ramps can actually "toss" lifters and cause instabilty issues in the valvetrain.

Harold (UD) made sure that with his fast ramp cams, the actual opening/closing velocties weren't much faster, if any faster at all than many stock type camshafts.

I know I've posted some negative information in recent months on some of these new designs, just wanted to make sure folks know exactly what we are trying to convey here, and than I'm not bad-mouthing all fast ramp designs from the various manufactures.

As far as the "Thumper" series goes, the really tight LSA's would be the wrong way to go for most Pontiac "street" engines right to start with....IMHO....Cliff

[Ron Landis]

were targeted for customers that want a cam to "hit a lick" but still have to drive to work or not be radical for whatever reason. I never liked the idea and told customers that the best way to describe it was as a cam that doesn't perform as well as it sounds. All they did was tighten up the lobe separation and in some instances..add duration. Makes no sense if you actually are after a performance gain. Works well for show cars with 3.08 gears and such. FYI.Ron

[Cliff R]

I hear ya. We went to a 247/254/108 hydraulic cam in a 455 build, sounded and felt like it was going to run mid-10's, VERY aggressive and strong mid-range power. It ran best of 12.28 @ 112 in a 3500lb car.....LOL......Cliff

[1974formula]

Thanks guys....I'm after some real power (no fluff) that will make my 406 hit the high notes rather than thump, I'll stick with a conventional roller.