Backfire issues - The 1947 - Present Chevrolet & GMC Truck Message Board Network

85chevy · 10-25-2005, 06:24 PM

I just put a new engine in my truck. I am getting a sporadic pop at idle and worse as the engine revs up. Someone said it could be the rockers out of adjustment, while others think it is the carb or spark plug wires. The pop is coming out of the exhaust. I am not sure which way to proceed. The engine ran fine when we broke it in 2 weeks ago, but started this last weekend. Anyone have any ideas?

Rud's 69-C10 · 10-25-2005, 06:40 PM

Seems simple enough.
1. check your plug wires vs firing order
2. IF they rocker arm/s did back off, you should be able to detect which cyclinder it is by sound-instead of pulling off both valve covers.
2a. Your're gonna need to replace the rocker arm nut.

Keep us updated
-Rudi-

85chevy · 10-25-2005, 07:12 PM

The firing order is good, as is the timing. I guess I will have to check the rockers this weekend.

sixty8c10 · 10-25-2005, 08:14 PM

if you have a rocker thats just a hair to tight it will pop but you won't really be able to hear it in the engine compartment....atleast not like the normal valve rattle when they are loose anyway

Nolowrider · 10-25-2005, 09:49 PM

I tend to think it is a valve issue. I would check the rockers first, may also be a sticky valve.

us111 · 10-25-2005, 09:55 PM

if it ran good at break in i would bet on a rocker arm issue,,.

10-25-2005, 06:24 PM	#1
85chevy Registered User Join Date: Jul 2004 Posts: 29	Backfire issues I just put a new engine in my truck. I am getting a sporadic pop at idle and worse as the engine revs up. Someone said it could be the rockers out of adjustment, while others think it is the carb or spark plug wires. The pop is coming out of the exhaust. I am not sure which way to proceed. The engine ran fine when we broke it in 2 weeks ago, but started this last weekend. Anyone have any ideas?

10-25-2005, 06:40 PM	#2
Rud's 69-C10 Registered User Join Date: Oct 2005 Location: Los Angeles, Ca Posts: 20	Re: Backfire issues Seems simple enough. 1. check your plug wires vs firing order 2. IF they rocker arm/s did back off, you should be able to detect which cyclinder it is by sound-instead of pulling off both valve covers. 2a. Your're gonna need to replace the rocker arm nut. Keep us updated -Rudi- __________________ '69 C10 Fleetside '69 Camaro (2nd Owner since 1978) '86 Bronco 4x4 '86 Ranger 4x4

10-25-2005, 07:12 PM	#3
85chevy Registered User Join Date: Jul 2004 Posts: 29	Re: Backfire issues The firing order is good, as is the timing. I guess I will have to check the rockers this weekend.

10-25-2005, 08:14 PM	#4
sixty8c10 MY EX DRIVES A BROOM Join Date: Nov 2003 Location: Herington, KS Posts: 869	Re: Backfire issues if you have a rocker thats just a hair to tight it will pop but you won't really be able to hear it in the engine compartment....atleast not like the normal valve rattle when they are loose anyway __________________ They say nobody's perfect. I'm a nobody, so I must be perfect. Building Nemo -1968 C10 Long Bed FRED -1947 KB-2 International Last edited by sixty8c10; 10-25-2005 at 08:16 PM.

10-25-2005, 09:49 PM	#5
Nolowrider Senior Member Join Date: Jan 2005 Location: New Orleans Posts: 1,365	Re: Backfire issues I tend to think it is a valve issue. I would check the rockers first, may also be a sticky valve.

10-25-2005, 09:55 PM	#6
us111 Registered User Join Date: Jul 2004 Location: ashland oh Posts: 660	Re: Backfire issues if it ran good at break in i would bet on a rocker arm issue,,.



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