Need advice from the masters

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Holy Roller

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I'm building a 383 thats been bored 30 over with 516 heads.And I'm putting it in my 68 barracuda for street use,possibly some street races. I am going to use Comp Cams Thumper series cam or Extreme Energy. What I need to know is the benefits. ..other than cost, between flat tappet cams and roller cams? And if anyone has any opinions on the Thumper VS. High energy. Your knowledge and help is greatly appreciated. Thank you
 
IMO the thumper cam sounds lots better then it performs. The profile was enginered to sound good. IMO end of story. RRR is to me the guy to ask. :burnout:MT
 
Flat tappet's cheaper. I tend to say either go solid roller, bush the block, and get all the benefits for the expense, or just run a flat tappet. IMO hydraulic rollers are too much for too little. I like the XE line in general. Cam size will depend on the rest of the package so any info you can add on the rest of the combo would be helpful.
 
My father runs the mother thumper in his big block. I run the MPP 284/528 cam. Both have the same duration. His sounds like a top fuel dragster. Mine sounds very mild. They make nearly the same HP and torque. His is misery to drive.

The only difference is my curve is flat and his is very peaky.
 
Flat tappet's cheaper. I tend to say either go solid roller, bush the block, and get all the benefits for the expense, or just run a flat tappet. IMO hydraulic rollers are too much for too little. I like the XE line in general. Cam size will depend on the rest of the package so any info you can add on the rest of the combo would be helpful.
The crank and rods are stock and the pistons are 30 over flat tops. I am thinking about putting larger exhaust valves and having the heads ported and polished. I'm not sure about the intake and carb yet. Opinions welcome..
 
My father runs the mother thumper in his big block. I run the MPP 284/528 cam. Both have the same duration. His sounds like a top fuel dragster. Mine sounds very mild. They make nearly the same HP and torque. His is misery to drive.

The only difference is my curve is flat and his is very peaky.
Are the cams flat or rollers? I like the sound of the Thumper but not the price of the roller set up...such as rockers from 600-1055 a set.
 
Are the cams flat or rollers? I like the sound of the Thumper but not the price of the roller set up...such as rockers from 600-1055 a set.


Both are flat tappet. The thumpr cams sound great. Can't deny that. Other than that in my experience they are crap. Basically they take a mild to moderate cam and cut it on a really small LSA. It makes it idle radical and lopy and makes it drive on the street like crap.
 
A roller setup will cost you close to $1000. Just for cam and lifters. I run a solid lifter flat tappet cam in my lowdeck, the Comp roller rockers were $600 alone. Both require you under the valve covers once in a while to set lash, unless your go to Hydraulic roller.
 
Use MRL roller lifters, you do not have to bush the lifter bores.

Lots of people say that and to the extent that you don't have a problem with oil bleeding out at full lift it's correct. However those lifters do nothing for oil control in the event of valvetrain failure, and do nothing to corect the lifter bore angles which (sadly) are just as acurately done as all other factory machining.
To me it's the same thing as buying top dollar pistons and running them on the original 70K mile worn factory bore.
If I'm going to pay four figures for the cam, pump drive, and lifters I want all the benefits- not just for it to run. It's not a matter of "will it work". It's a matter of how well will it work in the long run. So personally, I bush the bores. Every time. Period.
If it's not worth doing bushings, and the roller cam choice is a street type roller - I'll run a flat tappet and make the same power for a grand less money.
 
Thank you for all of your advice, the cost is a big factor and I do want more than a good sound. So maybe the flat tappet is the more economical choice.
 
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