Thumpr cams

[Green79Scottsdale]

Anyone here have actual first-hand experience with the Thumpr Series of cams from COMP Cams? They claim to "maximize that rough idle sound without negatively affecting vacuum, power or driveability." I have read conflicting reports on these cams, but I want first-hand reactions to them. While I love the lopey idle (what car guy or girl doesn't?!), I like throttle response and driveability better. This is all a bench-racing build in my head for a motor I may or may not acquire, so this should be considered research at this point. It would be going into a 3500 lb Monte SS, with 3.73 gears, 200-4R and what ever convertor will match good for street oriented driving. Thanks in advance for any advice.

 

[bucket]

I would like to know about these cams too. I've never talked to anybody that had one.

 

[87ChevyR10]

I had one in an '85 fleetside. Came with the truck when I bought it. The 350 was rebuilt with 305 heads to increase compression ratio. The truck had a nasty idle and sounded great! However, MPG was less than 10 in town. I'd get one for my current truck if I had the green.

Oh, and this cam will affect the vacuum. Def. not TBI friendly. That includes their mild variant.

I've read opinions from other forums about these cams. Seems the general consensus is these cams are worthless, save the choppy idle they produce. Many have claimed the cams do nothing to increase performance. Whether these claims are true or not, IDK.

 

[HotRodPC]

I'd never have one. This cam is called Thumper for a reason and only 1 reason. There is no efficientcy, no big power gain and is all show but no go. It's purpose is to make sound and sound badass for those who THINK they'll impress someone with sound. If you want a hot sounding gutless wonder, this is the cam design for you.

 

[Driver4r]

A hot 383 will only make about 350-375hp with a thumper cam. Just so you know.

 

[hirschdalechevy]

I have never ran one but they have their place in the performance world.

First off they are not going to make power in a 8.5 to 1 motor , (to much cam imo) , but if you want the drag cam sound in a 9.5 to 1 motor I don't see why they would not work well.

If you take a 9.5 to 1 motor and put a big cam in it with lets say a 110 lobe seperation that has a coppy idle your dynamic compression would be lets say in the mid 7's to 1 which equals not very good low end torque but it sound cool. If you take the same motor and run the small thumper that has a 107 lobe seperation you would bring up the dynamic compression ratio into the 8ish to 1 range which would give you really good low end torque and you would still have a coppy idle.

Thumper's have been dyno'ed and they have produced good number's. I think the down side that people have had with them is they are still missed matched for the motor's they are running them in. You are not going to take a bone yard stock 8.5 to 1 motor and put a thumper in it and have any luck.

The real street car's that run 11 to 1 can run the big cam's and keep the dynamic compression ratio where it needs to be , but for the guy's running 9.5 to 1 motor's that want the drag car idle , thats where the thumper comes into play and they keep the dynamic compression up so you still have good low end torque.

As with any motor you still need to feed it , good heads , intake , exhaust , etc.... The cam is just the brain's of the operation , if you dont have the right part's to go with it any cam will not perform that great.

So I think that with the right combo you can still have a kick ass motor for the street with the drag car sound that everybody love's.

 

[Green79Scottsdale]

I started looking around in some of the other forums I am a part of and I really believe hirschdale hit the nail on the head. With the right combination of parts this can be a nice cam. That is, of course, true with any cam, it needs the right supporting cast to be all it can be. I am not acquiring the motor in question after all, so somewhat of a moot point. Good discussion however.

 

[MikeB]

I'm new to this forum, but not to small block Chevys. I've always seen the Thumpr cams as "all show, no go" for folks who care only about having a lopey idle. It's kind of like having a 750 carb, when the engine would actually run better with a 500-600.

Assuming you have a 350 with around 9.0-9.5:1 compression, I think you'd be much better off with one of Isky's moderate duration cams with 108 LSA, like their #201264. Or Summit Racing's SUM-1785, which I believe is made by Crane. Both of these would preserve cylinder pressure, while having a little lope at idle and strong mid-RPM range power. Same might be true of CompCam's' 268H, but I expect it would have a little less lope and a little wider powerband.

If you engine is a later model with provisions for a factory roller cam, then an aftermarket roller is the only way to go.

 

[hirschdalechevy]

I have had two smallblocks at 9.5 to 1 with the 268h cams in them back in the day and they ran really well , but almost sounded stock to me.

I think still with the right combo , ( if you have to have that drag car idle) the thumper could still make some good number's on the dyno.Not saying that a different cam would'nt be a tic better but for some people who want that idle it may be worth 20 hp less to them but they would still have say a 350 hp motor which is healthy anyway. So people have already some write ups using thumper's and made good number's , even hughes engine's has there wiplash cam that is the same set up as a thumper for the mopar guy's and I have seen 360 small block dart that hauls ass with one , just saying.

 

[cbrodine]

I'd say yes you can make good power with Thumper cams...and this is only one example

https://www.youtube.com/watch?v=GTPMOsUuSzI

 

[chevyk10]

My philosophy is you have to look at what you have to work with and what rpm range you want to run in. You have to make a decisions on how much you want to spend and what's the most important sound or running the best?


Sent from my iPhone using Tapatalk

 

[hirschdalechevy]

I'd say yes you can make good power with Thumper cams...and this is only one example

https://www.youtube.com/watch?v=GTPMOsUuSzI

Sweet , if a guy had that motor in his car or truck at a show next to another guy with a same hp. range motor with a different cam in it purring like a kitten who do you think is going to get all the attention. I would not bitch about a street friendly 412 horse 350 at all.

 

[gpmorgan]

To get the most potential out of any performance cam is to install all the other components that make it work. Just look at the cam recommendations the manufacturer suggests. It's the complete package that makes it work.

 

[GreaseDog]

Sweet , if a guy had that motor in his car or truck at a show next to another guy with a same hp. range motor with a different cam in it purring like a kitten who do you think is going to get all the attention. I would not bitch about a street friendly 412 horse 350 at all.

The guy with a lower ,legit time slip on his dash where I come from.

 

[HotRodPC]

I'd say yes you can make good power with Thumper cams...and this is only one example

https://www.youtube.com/watch?v=GTPMOsUuSzI

Sweet , if a guy had that motor in his car or truck at a show next to another guy with a same hp. range motor with a different cam in it purring like a kitten who do you think is going to get all the attention. I would not bitch about a street friendly 412 horse 350 at all.

Of course the guy with the lopey cam is going to get the attention. That's my point. Rather than SOUND badass and still able to be beat, and made a fool of, I'd rather have Mild Sound, no attention, not expected to be fast and take their money. Some aren't aware, you can take a lopey cam, dial it in by advancing or retarding it the cam timing, which moves your power band range, but you can hide the lope to where it's not nearly as profound. That's what guys in sleepers do. But then you need to build and acquire all the other adders around that dialed in cam, just as if you were going to do with the cam straight up. This could involve a higher stall converter, a lower gear ratio, a single plane intake vs a dual plane and even different carb jetting. I really wish I had paid a bit more attention to that when younger. I think I'd have won more money. I won more than I lost but I think I could have won more.