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07-04-2016, 07:56 PM
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#1 |
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Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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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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07-04-2016, 08:04 PM
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#2 |
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Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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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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07-04-2016, 08:25 PM
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#3 |
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Registered User
Join Date: Jun 2015
Location: @
Posts: 890
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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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07-04-2016, 09:13 PM
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#4 |
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Registered User
Join Date: May 2016
Location: Henderson NC
Posts: 975
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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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07-04-2016, 09:42 PM
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#5 |
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Senior Member
 
Join Date: Dec 2013
Location: Gods country East,Tn
Posts: 8,545
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Re: Drum type pop from exhaust
Is it a drumming noise or a knocking noise ?
__________________
 1967 Factory short bed - Old school '71 - 350 / 4bolt / 487 heads / Edelbrock C3BX Muncie M-22 4 speed / Hurst Comp plus Factory 12 bolt posi 3.73 / 255-70-15 Smoothed firewall / Factory cowl induction Power disc brakes / power steering / 3.5-5" drop |
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07-04-2016, 10:11 PM
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#6 | |
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Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Drum type pop from exhaust
Quote:
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07-04-2016, 09:45 PM
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#7 |
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Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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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?
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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07-05-2016, 06:11 AM
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#8 | |
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Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Drum type pop from exhaust
Quote:
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