Slight miss at idle
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Joined: Dec 2009
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From: Spring
Slight miss at idle
Fully rebuild the 360 in my 73 F-100. Silly thing is I have the same miss I had before the rebuild, the miss isn't regular I will idle fine than one shudder then fine again. There is no sign of a miss at cruising speed and no hesitation at acceleration.
Things checked:
1. all vacuum lines, checked and double checked
2. New plugs, wires, cap, rotor, coil, points and condenser.
Could my primary resistance wire be going?
Could my ignition switch be bad?
or any other things?
Things checked:
1. all vacuum lines, checked and double checked
2. New plugs, wires, cap, rotor, coil, points and condenser.
Could my primary resistance wire be going?
Could my ignition switch be bad?
or any other things?
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I would put a timing light on each plug wire until you found which cylinder is missing. You'll know right away when the rhythm of the light pulses misses a beat on the effected cylinder.
From there you might be able to pinpoint the problem. But with all new parts and a rebuilt engine and the condition is the same I would look into what parts ARE the same between then and now.
Josh
From there you might be able to pinpoint the problem. But with all new parts and a rebuilt engine and the condition is the same I would look into what parts ARE the same between then and now.
Josh
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Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
If it truly is a "random" miss, meaning the miss isn't a particular cylinder I would suspect carburetion.
An outside possibility would be worn distributor shaft bushings causing a random misfire. I doubt this is the cause though, this would usually show at higher RPM or durring acceleration.
You also might try opening up the spark plug gap a few thousandth's of an inch.
If you're still running the stock distributor with points, the breaker plate was notorious for going bad and causing timing/dwell problems although, again, this is a problem that usually shows up at above idle speeds.
Also, there should be a small ground wire inside the distributor that grounds the breaker plate to the distributor body. Check the condition of this wire.
An outside possibility would be worn distributor shaft bushings causing a random misfire. I doubt this is the cause though, this would usually show at higher RPM or durring acceleration.
You also might try opening up the spark plug gap a few thousandth's of an inch.
If you're still running the stock distributor with points, the breaker plate was notorious for going bad and causing timing/dwell problems although, again, this is a problem that usually shows up at above idle speeds.
Also, there should be a small ground wire inside the distributor that grounds the breaker plate to the distributor body. Check the condition of this wire.
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