Big Mutha Thumpr cam?
#2669773
06/25/19 12:37 PM
06/25/19 12:37 PM
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Joined: Aug 2009
Posts: 740 Anderson, IN
1969RR
OP
super stock
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OP
super stock
Joined: Aug 2009
Posts: 740
Anderson, IN
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Building a 496 RB 440. 11.5-1, Holley Super Sniper 440 SEZ heads, 0.051" head gaskets. Looking at different cam and cam profiles. I've talked to Dwayne, and he said Comp's are kinda hard to get at this time. I'm looking for mid-range HP and torque. Looking on the Comp site, I see the Mutha Thumpr is available but not sure if it would work for my needs. So much info to digest! Thumpr has a LSA of 107 where most of the others are 110-112 LSA. Timing events are confusing too. Example: The Mutha Thumpr exhaust closes at 49 ATDC opens at 82 BBDC, intake opens 42 BTDC, closes at 69 ABDC whereas the XR286HR-10 exhaust closes at 2 ATDC, opens at 55 BBDC, intake opens 12 BTDC closes at 44 ABDC. duration @ 0.050 is about the same on both, but lift is a bit different. What does all that mean and do? Also looked at the Trick Flow Track Max and it has a lift of 0.600. Quite a bit higher than either Comp. I've never talked with anyone that has used the Mutha Thumpr, so no idea about that one. You guy's that understand all this are a genius if you ask me! So much confusion. Could anyone shed some light for me? This is mainly a street driven, but driven hard vehicle. (1970 Challenger) Thanks in advance! Jeff
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Re: Big Mutha Thumpr cam?
[Re: AndyF]
#2669815
06/25/19 02:53 PM
06/25/19 02:53 PM
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Joined: Aug 2009
Posts: 740 Anderson, IN
1969RR
OP
super stock
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OP
super stock
Joined: Aug 2009
Posts: 740
Anderson, IN
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Yea, forgot some info! 5 speed Tremec, 4.10 Dana. Shooting for 550-600 HP. I usually run 97 with a mix of 110 fuel. I don't care if it has a rougher idle, but I do want to drive it on the street too. I am interested in a hydraulic roller. I've scoured the interweb and have found so many builds, dyno runs etc from all different cams I know the duration plays into idle quality, but why so many variations of degrees of opening and closing? Andy, I watch closely the ones you build and notice you stay close to the 240-242 duration range and have good idle quality, yet produce great power. That's what I'm looking for, Thanks for the response! Jeff
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Re: Big Mutha Thumpr cam?
[Re: AndyF]
#2670091
06/26/19 09:07 AM
06/26/19 09:07 AM
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Joined: Jan 2003
Posts: 18,024 S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 18,024
S.E. Michigan
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According to the little I have learned from friends more into FI than I will ever be.....I feel the 107 is probably not a good idea.
Rich H.
Esse Quam Videri
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Re: Big Mutha Thumpr cam?
[Re: ZIPPY]
#2670107
06/26/19 09:49 AM
06/26/19 09:49 AM
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Joined: Jan 2003
Posts: 14,531 So. Burlington, Vt.
fast68plymouth
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I Live Here
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So. Burlington, Vt.
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Not only the 107, but the whole bunch of extra ex duration providing even more overlap........ doesn’t sound like a real EFI friendly choice.
Someone might have one of those cams on the shelf somewhere....... but I wouldn’t be too confident Comp does.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Big Mutha Thumpr cam?
[Re: AndyF]
#2671327
06/28/19 09:43 PM
06/28/19 09:43 PM
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Joined: Jan 2003
Posts: 10,081 Frostbitefalls MN (Rocky&Bullw...
gregsdart
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I Live Here
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Posts: 10,081
Frostbitefalls MN (Rocky&Bullw...
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I used a thumpr cam, hr 235/249/107 in a 408 stroker smallblock. The EQ iron heads flowed 272 @ .600, with great midrange numbers. The motor has an airgap intake, 850 Quickfuel carb, 10.1 compression, and the cam is at 105, rather than the recomended 102. It made 504 hp at 5700 rpm, and 519 tq at 4700. I use a true 4,000 stall converter, and in a 65 dart the thing is a beast. Properly set up with slicks, i have a good idea of it being able to run hi 10s. If you look at circle track cams, the LSAs are very narrow in a lot of cases, because they don't need to worry a rats butt about manners below a certain rpm, like 3,000 rpm for instance. That is pretty much what you get with a thumpr cam. It is best to use the max compression you can though, to help offset the early exhaust opening of the thumpr cams. Also, matching the converter or running more gear ratio in a stick car will work much better given the extra overlap these cams have.
Last edited by gregsdart; 06/28/19 09:46 PM.
8.582, 160.18 mph best, 2905 lbs 549, indy 572-13, alky
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