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Discussion Starter · #1 ·
I need help. Last year at Cruisin the Coast I was left stranded when my Accel coil died. I put a stock coil on and it started running bad only at WOT. Half throttle its fine, 3/4 throttle its fine, but at wide open it pops. Now here I am a year later and cruisin the coast is back. I figured if I put another Accel coil I would be back to running good but no. Replaced coil with Accel one, tuned Holley 750, set timing at 12, replaced plugs, and still pops like crazy when I nail it. Everyone around me is smoking the tires at the lights and i'm just poping and looking stupid. Please help! 350 .080 over, 10.5 to 1, mild cam, camel hump heads, performer intake, holley 750. Thanks! Oh and if you are not on the MS gulf coast this week you should be!
 

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Could you have a weak valve spring? It might have enough pressure to work until the rpm comes up and then start floating prematurally.

I'm sure there will be more guesses soon.

Good luck figuring it out!
 

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It does sound suspiciously like a weak valve spring or cam going flat, but could also be ignition related depending on the type you are running. You didn't say if it was points, HEI, aftermarket electronic, etc. If it's points you could have a problem with them bouncing (weak) at high RPM or an HEI module could be failing you
 

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Discussion Starter · #6 ·
Sorry about that, it's an HEI with Accel coil. No points. It's confusing me because I had the Accel coil and it ran fine, then it broke and I put on a stock coil and started having this problem. When I put another Accel on it didn't go back to running good???????
 

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Discussion Starter · #8 ·
I read somewhere that if I have a Holley 750 with the vacuum line for the advance plugged in at the bottom of the carb it can cause this because that would be ported vacuum and it needs full vacuum. Anyone ever heard of this?
 

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When I was running a 750 vac secondary I tried running the vacuum to the advance from both ported and direct sources, neither caused popping at high rpm at least for my engine.
 

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I read somewhere that if I have a Holley 750 with the vacuum line for the advance plugged in at the bottom of the carb it can cause this because that would be ported vacuum and it needs full vacuum. Anyone ever heard of this?
Tucker. The bottom port should be full manifold vacuum. However, that wont matter at WOT. There shouldn't be very much vacuum at WOT, so you are just working off of mechanical advance. I think you should take all of the other poster's advice and check for a cam going bad or weak valve springs.
 

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I have a similar issue cruizing down the road at about 3000rpm. It sounds fine but you can here a pop every few seconds. Its done it ever since the engine was put in though so i think its the exhaust system causing it. Sounds like his is much more serious but if it is the cam or valves i thought you could here it just by reving the motor, not only WOT. Ive miss adjusted valves before and it was apparent long before WOT. It also caused extreme loss in the motors strength.
 
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