Slight popping and miss when driving. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jefe · 07-07-2002, 07:17 PM

Its a 350 with a TH350, new heads, new intake manifold, new carb, new plug wires/plugs/rotor/cap/points and condensor. When driving, it starts to chug back and forth ever once and awhile, also a slight popping out the exhaust. Timed it with a light and it's in time, dwell is perfect. Can't figure it out. Any help please..

Douglas.

jlmtrout · 07-07-2002, 07:51 PM

Not to overlook the obvious, but have you double checked the firing order? How old is the coil and are the connections tight, including the wire to the distributor cap? Also, check the wire from points to coil. How about the wire from ignition switch to coil? Could you have cracked a spark plug? Just some thoughts, these things have perplexed me before. You might try checking under the hood in the dark with the engine running and rev it up to see if there are any stray sparks. Just my .02 worth. Good luck and keep on truckin'!---Jerry

P.S. you may have an exhaust valve too tight
and it may not be closing completely. You
can use a vacuum guage to check. If needle
flutters, and it isn't backfiring through the
carb, check the exhaust valves. (New condensers
can be bad, and check connection to points.)

Jefe · 07-07-2002, 09:34 PM

Actually that is one of the first things I checked and double checked...hehe the firing order that is. Uhmmm connection to points is good as well as coil connections, tried a new coil...same result. Stray sparks is a good idea... any other thoughts?

Douglas.

Sinister · 07-07-2002, 10:37 PM

you could pull a valve cover and check
if your rockers arms (lifters) are adjusted right
if you used the old nuts, they can back out...
then you'll have a lifter out of adjustment and get that popping noise from a valve...
just a thought, happened to me...

07-07-2002, 07:17 PM	#1
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	Slight popping and miss when driving. Its a 350 with a TH350, new heads, new intake manifold, new carb, new plug wires/plugs/rotor/cap/points and condensor. When driving, it starts to chug back and forth ever once and awhile, also a slight popping out the exhaust. Timed it with a light and it's in time, dwell is perfect. Can't figure it out. Any help please.. Douglas.

07-07-2002, 07:51 PM	#2
jlmtrout Registered User Join Date: Jul 2002 Location: Memphis, Tn Posts: 194	Not to overlook the obvious, but have you double checked the firing order? How old is the coil and are the connections tight, including the wire to the distributor cap? Also, check the wire from points to coil. How about the wire from ignition switch to coil? Could you have cracked a spark plug? Just some thoughts, these things have perplexed me before. You might try checking under the hood in the dark with the engine running and rev it up to see if there are any stray sparks. Just my .02 worth. Good luck and keep on truckin'!---Jerry P.S. you may have an exhaust valve too tight and it may not be closing completely. You can use a vacuum guage to check. If needle flutters, and it isn't backfiring through the carb, check the exhaust valves. (New condensers can be bad, and check connection to points.) __________________ '68 c-10 long wheelbase fleetside, been in family since new, originally 250 3 speed Now (389) 350 .060 over 3.75 stroke,Edelbrock Performer RPM 70cc heads and Intake 600 cfm Edelbrock,Small Comp Cams retro-roller cam and roller rockers,9:1 cr, headers, HEI,Old Air a/c, 72 power disc brakes w/stainless lines, 3.42 gear,T-56 6-speed, original paint(what's left of it). Dakota Digital Dash

07-07-2002, 09:34 PM	#3
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	yup Actually that is one of the first things I checked and double checked...hehe the firing order that is. Uhmmm connection to points is good as well as coil connections, tried a new coil...same result. Stray sparks is a good idea... any other thoughts? Douglas.

07-07-2002, 10:37 PM	#4
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	you could pull a valve cover and check if your rockers arms (lifters) are adjusted right if you used the old nuts, they can back out... then you'll have a lifter out of adjustment and get that popping noise from a valve... just a thought, happened to me... __________________ Beat it to fit, Paint it to match...



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