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-   -   Engine sbc combanation (http://www.hotrodders.com/forum/engine-sbc-combanation-178493.html)

don77camaro 05-27-2010 09:52 AM

Engine sbc combanation
 
Hey i have a question i am building a engine, or getting parts together. I bought a Comp Cams Big Mutha Thumpr 299THR7. The rpm range is 2500 to 6500. Valve lift on the intake is 0.533 and 0.519 on the exhaust. The engine i have is a 350 board 40,and came factory with roller cam,im going to use 3.750 crank. Just wondering what would be the lowest runner i could use with this cam would a afr 195 work,or would it perform better with GM fast burn heads? Those are the 2 heads im wanting to run, but cant make my mind up on which of them to use. The compression ratio will be about 10:5. If any body has any head recommendation it would be appreciated, or advice on this cam shaft. Ive heard good stuff about the thumper line, but also heard bad. THanks for reading

don77camaro 05-27-2010 09:55 AM

RPM range is not 6500 its 6200 at max

my87Z 05-27-2010 01:32 PM

i dont know who you have heard good things from about the comp thumper cams but i have never heard anything but bad about them, "they're all show and no go" they are a cam designed to give you the solid cam sound but with out the actuall power behind it. the AFR 195's would be a decent fit, so would a set of DART iron eagle Platinum 200cc, or RHS pro action 200cc, the Brodix ik200's are nice as well, since you are building a 385 that cam's rpm range will be little lower to say about 2200-5900 and with this rpm range i wouldn't go with less than a 190cc intake runner on the heads, and i would stick with a dual plane intake. IMHO i would look for another cam

techinspector1 05-27-2010 01:41 PM

Don, I don't think there are too many board members here who would choose a Thumpr cam. It's considered by some to be a "poser" cam, one that a 16 year old kid might choose. Maybe he wanted the thump because it sounds like a race car motor and he didn't know any better from a performance standpoint.

If you like the sound, great, go for it. If you want performance, there are better choices.

I personally would not use a 10.5:1 static compression ratio in a street motor. 9.5:1 would be plenty in my opinion and would be easier to prevent detonation with crummy fuel.

Runner selection, in my opinion, should be 195-210 for a 383/385 SBC, depending on static compression ratio.

ericnova72 05-27-2010 01:45 PM

Not to harp on you, but the cam should be close to the last thing you buy, not the first. You pick the cam to fit well with all the other parts, not buy the parts to fit the cam choice.

don77camaro 05-28-2010 12:13 AM

:spank: I thought this would be a good cam,and Ive already bought it. So i will have to use it. is the lobe separation thats the problem, or overlap. So these cams are pretty much for sound, i thought it would make good power. i should have posted and asked

don77camaro 05-28-2010 12:18 AM

Should i try to sell the cam

don77camaro 05-28-2010 07:43 AM

Its already shipped please read
 
The cam already shipped. I know you guys know whats good and whats not. I read on these post and the replies are crazy. This site has alot of intelligent people for sure, and i know you can help me understand. I don't care about the sound i care about performance, and it had good lift,and the rpm looked to be where i would want it. Is it the exhaust overlap that hurts it,and if so wouldn't it only decrees power at low rpm. I just got back into building engines. I was spending time boxing, and I didn't know the cam was just for sound, i would have never bought it,and i have kids,and not alot of money so when i get extra money i want it to be on quality parts not some cam that makes your car sound stronger than it is, i could care less about sound performance is important to me, please let me know what the problem is with the cam

cobalt327 05-28-2010 07:56 AM

Quote:

Originally Posted by don77camaro
i could care less about sound performance is important to me, please let me know what the problem is with the cam

The cam (as you've guessed) has an inordinate amount of exhaust duration, a narrow LSA and is made to have a race cam sound yet be usable on the street.

That said, all is not lost!

Depending on who you ordered it from, get on the blower to them and just tell them that you want to return the unused, unopened cam for an exchange on another different cam. Likely, they will give you a return authorization or something like that along with instructions on how to return it for credit/exchange/refund.

I know of no reputable dealer who wouldn't accept a return- you'll only have to eat the shipping charges but that's a better alternative to using a cam that's not what you want.

cobalt327 05-28-2010 08:02 AM

It occurred to me that if you get ahold of the company who sold it to you, you may be able to just tell the deliverer to return it to the sender when it comes, if you or someone will be there. I would check w/them and see.

don77camaro 05-28-2010 02:50 PM

Hey im going to run the thumpr cam,and im going to degree it ,and run the recommended parts,and i have a friend at bb&t racing who has a engine dyno,and im going to do a swap and see the difference of horsepwer, im going to see if an extreme energy roller will make more than this cam, or if any one knows of a cam with close to same lift on intake and exhaust that would like to see which would do better. The heads are afr 195cc

don77camaro 05-28-2010 02:52 PM

I really want to see some actual dyno runs for the thumper cam with adv. duration of 299

ericnova72 05-28-2010 03:43 PM

I have seen on another board where engine builder Joe Sherman(maybe you know the name?, won the first Jeg's Engine Masters contest) has good results with the two biggest Thumpr cams in 383-406 street builds but doesn't recommend any of the smaller ones. IIRC seems like he is installing them 6-7 advanced.

You might try looking for his posts over at www.speedtalk.com in the engine forum, his handle is bigjoe1

techinspector1 05-29-2010 02:38 AM

Quote:

Originally Posted by ericnova72
I have seen on another board where engine builder Joe Sherman has good results with the two biggest Thumpr cams in 383-406 street builds. IIRC seems like he is installing them 6-7 advanced.

See, just when you think you know the facts on something, along comes new information. Thanks Eric, I'll be more careful in my description of these cams in the future. :thumbup:

don77camaro 05-31-2010 07:54 PM

Quote:

Originally Posted by ericnova72
I have seen on another board where engine builder Joe Sherman(maybe you know the name?, won the first Jeg's Engine Masters contest) has good results with the two biggest Thumpr cams in 383-406 street builds but doesn't recommend any of the smaller ones. IIRC seems like he is installing them 6-7 advanced.

You might try looking for his posts over at www.speedtalk.com in the engine forum, his handle is bigjoe1

Thanks im going to check that out for sure


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