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Old 07-04-2016, 07:56 PM   #1
Mrturner1
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Drum type pop from exhaust

So I just put in a new MSD pro billet HEI and I fired the truck up and it runs kindof rough and has this sound from the exhaust like somebody hitting a drum about once one or two times per second. What is that? It's not really a pop, but it's definetly coming from the exhaust.
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Old 07-04-2016, 08:04 PM   #2
Mrturner1
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Re: Drum type pop from exhaust

I put the distributor back in exactly like I took the old one out. Should I just start from scratch and pull the distributor and set it up at TDC?
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Old 07-04-2016, 08:25 PM   #3
firedemon
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Re: Drum type pop from exhaust

sounds like the timing is off it runs so cant be that bad try turning distributor somewhere between 4 and 10 deg before with no vac to the advance
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Old 07-04-2016, 09:13 PM   #4
garyd1961
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Re: Drum type pop from exhaust

Check the firing order. Just to be sure, I've seen experienced mechanics get wires crossed.
How is it running other than the sound?
Is the distributer the only thing you changed?

Last edited by garyd1961; 07-04-2016 at 09:19 PM.
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Old 07-04-2016, 09:42 PM   #5
Grumpy old man
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Re: Drum type pop from exhaust

Is it a drumming noise or a knocking noise ?
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Old 07-04-2016, 09:45 PM   #6
davepl
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Re: Drum type pop from exhaust

Pair of plug wires reversed? Check them.

Off by one? Does significantly advancing or retarding improve it?
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Old 07-04-2016, 10:11 PM   #7
Mrturner1
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Re: Drum type pop from exhaust

Quote:
Originally Posted by Grumpy old man View Post
Is it a drumming noise or a knocking noise ?
Just a pop kinda noise, I think I dropped the distributor in a notch or two off again. I don't get how I do that except that the oil pump drive slot gets turned a bit when I take out the old distributor. I always put it right back, and I thought it wouldn't drop all the way if it was off.
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Old 07-05-2016, 06:11 AM   #8
Mrturner1
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Re: Drum type pop from exhaust

Quote:
Originally Posted by davepl View Post
Pair of plug wires reversed? Check them.

Off by one? Does significantly advancing or retarding improve it?
Off by one! lol dangit that's twice in a week!
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