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Old 08-01-2020, 06:29 PM   #12
hjewell2
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Join Date: May 2011
Location: mich
Posts: 654
Re: 454 with comp Thumper cam troubles

Quote:
Originally Posted by Ironangel View Post
Detonating under a slight load is to much timing...Knowing what the head casting numbers are, and what your timing is set at would help. I'm curious as to what timing gear set your running, specifically what slot your cam gear is in? You may have the cam degreed in to far advanced via the wrong keyway slot. That cam wont make much vacuum at idle with that much overlap so your vacuum canister plus mechanical timing, plus the initial timing can be adding to much total timing causing the detonation. Need to know exactly how much each timing event is adding...I'm running a 108 overlap in my big block with 12.5:1 domes in 106 cc closed chambered iron heads. No Vacuum advance at all, just initial and mechanical for a total of 35 degrees @ 3000 rpm. My cams retarded 6 degrees to #1 intake. If your going to run a cam like that you have to know your timing events and how much each is adding and when...Start over before you break a ring land...Just Sayin PS. Contrary to what many say, that cam will idle and make power if its degreed in right!
These cams run even better with fixed timing , get better throttle response higher vacuum , and do not use
the vacuum advance , shoot for 34 to 36 total timing, you will notice better idle due to carb butterfly not exposing the transfer slot to get idle to about 1000 rpm.
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