Engine miss, drivin' me nuts - The 1947 - Present Chevrolet & GMC Truck Message Board Network

walker · 09-29-2005, 09:52 PM

I have an engine miss that is really bothering me. It is somewhat intermittent and so has been difficult to find. When the engine is cold it seems to run fine, most of the time, then starts to develop an erratic idle and stumbles up to 2500 rpm. After that it seems to smooth out. I had some trouble in the past with the mechanical advance sticking with the weights out, but I check that and the timing seems to be good. When I had it apart I looked at the cap and rotor and did not see any tracking, or burning. It is an HEI dizzy, on a 350, with a 1405 on a performer.
What is the best method of tracking down a miss? The engine only has a few thousand miles on it, and sometimes it purrs along just fine, so I do not suspect a valve problem.
Any ideas on this would be appreciated.

muddyole 69 · 09-30-2005, 02:21 AM

sounds like the same trouble I have on my dump truck I am leaning toward the module in the dist going south will probably replace it along with all the other usuall tune up parts and see what happens good luck Mike

walker · 09-30-2005, 08:56 PM

Let me know what happens. I have reasonably new wires and plugs, plugs are gapped at .045, and are light tan color on the electrodes, and everything seems fine. I can't even pin it down to a single cylinder.

rkarr · 10-01-2005, 02:55 AM

Quote:

Originally Posted by walker

I have an engine miss that is really bothering me. It is somewhat intermittent and so has been difficult to find. When the engine is cold it seems to run fine, most of the time, then starts to develop an erratic idle and stumbles up to 2500 rpm. After that it seems to smooth out. I had some trouble in the past with the mechanical advance sticking with the weights out, but I check that and the timing seems to be good. When I had it apart I looked at the cap and rotor and did not see any tracking, or burning. It is an HEI dizzy, on a 350, with a 1405 on a performer.
What is the best method of tracking down a miss? The engine only has a few thousand miles on it, and sometimes it purrs along just fine, so I do not suspect a valve problem.
Any ideas on this would be appreciated.

Sounds like a carburetor issue to me... Especially when you mention that it runs better cold than warm... Does your carb have an "off-idle" circuit? If so, it's probably dirty......
Without seeing it personally, I can't be sure, but it sounds suspect to me...

walker · 10-01-2005, 12:20 PM

Well, I had looked at the plugs wires at night while it was running and didn't see any stray sparks, but the engine was cold. I checked it last night after driving it home, hot, and there were stray sparks everywhere. It looked like some movie special effects. So, I will go get some plugs wires today and see if that does the job.

cableguy0 · 10-01-2005, 12:37 PM

get a good set of wires instead of the crap on the shelf at the parts store. taylors are a great wires and run about 50 bucks a set. stay away from accel wires they will cause the same light show you have now.

09-29-2005, 09:52 PM	#1
walker Registered User Join Date: Jul 2003 Location: north of Phx AZ about 30 miles Posts: 698	Engine miss, drivin' me nuts I have an engine miss that is really bothering me. It is somewhat intermittent and so has been difficult to find. When the engine is cold it seems to run fine, most of the time, then starts to develop an erratic idle and stumbles up to 2500 rpm. After that it seems to smooth out. I had some trouble in the past with the mechanical advance sticking with the weights out, but I check that and the timing seems to be good. When I had it apart I looked at the cap and rotor and did not see any tracking, or burning. It is an HEI dizzy, on a 350, with a 1405 on a performer. What is the best method of tracking down a miss? The engine only has a few thousand miles on it, and sometimes it purrs along just fine, so I do not suspect a valve problem. Any ideas on this would be appreciated. __________________ Andy,Phx AZ '67 C-10 (Ahhh, done at last. Well there is that disk front end I want to put in and...) "23 C-Cab-sold '48 Ford 8N tractor(still working) '67 Scout(Now on the road) '70 MG B.-sold

09-30-2005, 02:21 AM	#2
muddyole 69 Senior Member Join Date: Jan 2004 Location: SE Ohio Posts: 1,121	miss sounds like the same trouble I have on my dump truck I am leaning toward the module in the dist going south will probably replace it along with all the other usuall tune up parts and see what happens good luck Mike __________________ hav'n fun be'n me

09-30-2005, 08:56 PM	#3
walker Registered User Join Date: Jul 2003 Location: north of Phx AZ about 30 miles Posts: 698	Let me know what happens. I have reasonably new wires and plugs, plugs are gapped at .045, and are light tan color on the electrodes, and everything seems fine. I can't even pin it down to a single cylinder. __________________ Andy,Phx AZ '67 C-10 (Ahhh, done at last. Well there is that disk front end I want to put in and...) "23 C-Cab-sold '48 Ford 8N tractor(still working) '67 Scout(Now on the road) '70 MG B.-sold

10-01-2005, 12:20 PM	#5
walker Registered User Join Date: Jul 2003 Location: north of Phx AZ about 30 miles Posts: 698	Well, I had looked at the plugs wires at night while it was running and didn't see any stray sparks, but the engine was cold. I checked it last night after driving it home, hot, and there were stray sparks everywhere. It looked like some movie special effects. So, I will go get some plugs wires today and see if that does the job. __________________ Andy,Phx AZ '67 C-10 (Ahhh, done at last. Well there is that disk front end I want to put in and...) "23 C-Cab-sold '48 Ford 8N tractor(still working) '67 Scout(Now on the road) '70 MG B.-sold

10-01-2005, 12:37 PM	#6
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	get a good set of wires instead of the crap on the shelf at the parts store. taylors are a great wires and run about 50 bucks a set. stay away from accel wires they will cause the same light show you have now. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.



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