Idling issue
Idling issue
I need some help guys and gals. I have a 64 Comet. A couple years ago, I sent Motorcraft 1100 carb out under recommendation of a link on the forum. Great work, carb came back anodized and perfect. I also have installed pertronix electronic ignition. Seemless install. I have always had an idling issue. Just today I took her for a spin and she runs good under load, just won't idle worth a cr%&$p. Dies at a stop if I don't keep it running. It is definitely worse when it is hot outside. In the recent past I had a flooding issue with carb. Finally resolved that issue as the float was hanging up on the float pivot and would get stuck open and flood everything. Coasting down a hill in gear, it will do the pop pop seeming like a backfire but everything seems on time. It will eventually struggle to stay idling if I don't keep it running and die. Maybe and intake leak? Very aggravating and takes a lot out of the enjoyment of using it to tool around town. Any advice on adjustments or tweaks to resolve this would be great!
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Joe Travers
- Posts: 2436
- Joined: Mon Sep 21, 2020 6:23 pm
- Location: Louisiana
Re: Idling issue
Check everything on the ignition side including timing, first and get that out of the way. I'm betting you have a vacuum leak, without looking at it firsthand. Richen up the choke and see if it smooths out. I ran into this problem recently with a Autolite 1100. Some yo-yo stripped out the vacuum advance port on the carb and it was sucking air. running lean. Would smooth out at higher idle when choked but still spit and sputter a bit. Have to drill out and tap the port for adapter fitting.
Good luck!
JT
Good luck!
JT
1963 1/2 Custom Hardtop
342 stroker, solid roller, T-10, 3.55 posi
Re: Idling issue
Thanks for the input. I will get in there and check for a vacuum leak....
Re: Idling issue
with engine at operateing temp...take air cleaner off,,,,,cup hands together over carb and try to choke engine and make it die...if it won't or is hard to make die,,,you have a pretty bad vacumn leak,,,,,pop
pop/glenda
Re: Idling issue
I did what you said Pop and engine died right away. So that is good. I went back and reset the timing with an analyzer and light. It was a couple degrees off. Seems to run real good now. Of course the temperature dipped down here in GA the last couple days. The mild popping coasting down a hill is gone as well. I think that was it. I found this reference to setting the timing on the 6 cyl 170. Pretty good step by step description. Thanks for y'alls help. You know I'll be back if that wasn't the probem! 
1. If the recommended engine idle speed is in excess of 500 rpm, set the idle at 500 rpm for purposes of setting the ignition timing. If the recommended idle is below 500 rpm, do not alter it. Refer to for idle speed setting procedures. In all cases, references in this procedure are for idle speeds with the engine at its full operating temperature.
2. Aim the timing light at the timing mark and pointer on the front of the engine. If the marks which you made on the pointer and timing mark align when the timing light flashes, set the idle to its proper specification, remove the timing light and tachometer, and connect the vacuum lines at the distributor. If the marks do not align when the light flashes, continue with the procedures for ignition timing adjustment.
3. Stop the engine with the timing light still connected. Loosen the distributor hold-down clamp slightly.
4. Start the engine again, and observe the timing mark and pointer with the timing light. Timing may be advanced by turning the distributor of a six-cylinder engine counterclockwise. On V8 engines, the timing is advanced by turning the distributor clockwise. When the proper timing has been attained (when the paint marks on the pointer and the timing mark align), stop the engine. Tighten the distributor hold-down clamp. Restart the engine and check the timing to make sure that it was not altered while you tightened the hold-down clamp.
5. On all engines, except pre-1968 six-cylinder models, the centrifugal advance must be checked for proper operation. Start the engine and accelerate it to approximately 2,000 rpm. Properly aim your timing light at the mark and pointer. If the ignition timing advances, the centrifugal advance mechanism is functioning properly. Note the engine speed when the advance begins, and the amount of advance which is attained. Stop the engine.
6. On all engines except pre-1968 high-performance engines equipped with centrifugal advance distributors, connect the vacuum line at the outer side of the diaphragm. Start the engine and accelerate it to approximately 2,000 rpm. Note the speed when the advance begins and the amount of advance attained. On pre-1968 six-cylinder engines, any advance indicates that the vacuum advance is in proper working order. On all others equipped with vacuum advance, the timing should now advance sooner and farther than before the vacuum lines were connected. If this occurs, the vacuum advance is working properly. Stop the engine.
7. On dual-diaphragm distributors, check the vacuum retard operation by connecting the intake manifold vacuum line to the inner side of the diaphragm. Start the engine and adjust the carburetor to its normal idle speed. The initial timing should retard to approximately top dead center (TDC) if the initial ignition timing is correct. On some engines, the timing may retard as far as six degrees after top dead center (ATDC).
8. If the vacuum advance (or vacuum retard, in the case of dual-diaphragm distributors) is not functioning properly, it will be necessary to remove the distributor from the engine and have it tested on a distributor testing machine. Refer to for distributor removal procedures. If either diaphragm is leaking or cannot be calibrated to specifications, it will be necessary to replace the diaphragm unit.
9. If all vacuum advance and retard units are found to be in proper working order, remove all testing equipment from the engine.
1. If the recommended engine idle speed is in excess of 500 rpm, set the idle at 500 rpm for purposes of setting the ignition timing. If the recommended idle is below 500 rpm, do not alter it. Refer to for idle speed setting procedures. In all cases, references in this procedure are for idle speeds with the engine at its full operating temperature.
2. Aim the timing light at the timing mark and pointer on the front of the engine. If the marks which you made on the pointer and timing mark align when the timing light flashes, set the idle to its proper specification, remove the timing light and tachometer, and connect the vacuum lines at the distributor. If the marks do not align when the light flashes, continue with the procedures for ignition timing adjustment.
3. Stop the engine with the timing light still connected. Loosen the distributor hold-down clamp slightly.
4. Start the engine again, and observe the timing mark and pointer with the timing light. Timing may be advanced by turning the distributor of a six-cylinder engine counterclockwise. On V8 engines, the timing is advanced by turning the distributor clockwise. When the proper timing has been attained (when the paint marks on the pointer and the timing mark align), stop the engine. Tighten the distributor hold-down clamp. Restart the engine and check the timing to make sure that it was not altered while you tightened the hold-down clamp.
5. On all engines, except pre-1968 six-cylinder models, the centrifugal advance must be checked for proper operation. Start the engine and accelerate it to approximately 2,000 rpm. Properly aim your timing light at the mark and pointer. If the ignition timing advances, the centrifugal advance mechanism is functioning properly. Note the engine speed when the advance begins, and the amount of advance which is attained. Stop the engine.
6. On all engines except pre-1968 high-performance engines equipped with centrifugal advance distributors, connect the vacuum line at the outer side of the diaphragm. Start the engine and accelerate it to approximately 2,000 rpm. Note the speed when the advance begins and the amount of advance attained. On pre-1968 six-cylinder engines, any advance indicates that the vacuum advance is in proper working order. On all others equipped with vacuum advance, the timing should now advance sooner and farther than before the vacuum lines were connected. If this occurs, the vacuum advance is working properly. Stop the engine.
7. On dual-diaphragm distributors, check the vacuum retard operation by connecting the intake manifold vacuum line to the inner side of the diaphragm. Start the engine and adjust the carburetor to its normal idle speed. The initial timing should retard to approximately top dead center (TDC) if the initial ignition timing is correct. On some engines, the timing may retard as far as six degrees after top dead center (ATDC).
8. If the vacuum advance (or vacuum retard, in the case of dual-diaphragm distributors) is not functioning properly, it will be necessary to remove the distributor from the engine and have it tested on a distributor testing machine. Refer to for distributor removal procedures. If either diaphragm is leaking or cannot be calibrated to specifications, it will be necessary to replace the diaphragm unit.
9. If all vacuum advance and retard units are found to be in proper working order, remove all testing equipment from the engine.