The Ford Barn

DJ S · 10-30-2017, 07:44 PM

I have this strange issue where my tudor will idle beautifully after just a few minutes of running but once it warms up to normal operating temperatures, the idle is extremely rough to the point where you think that the car might die on you. The car however does fine driving down the road and under load but once you stop at a stoplight, the car runs terribly. I also experience a hesitation in throttle response from idle. I'm thinking it might be a cracked intake manifold that is fine when the car is cold because the crack is retracted and not letting a whole lot of air in and when the car warms up, the crack expands allowing more air in creating a lean mixture. What are your thoughts?

1crosscut · 10-30-2017, 08:20 PM

When it starts running rough spray starting fluid around the manifolds. If the rpm's change you have a leak.

Jacksonlll · 10-30-2017, 08:35 PM

Also, make sure the flanges at the carb connection are flat and not leaking.

lindy williams · 10-30-2017, 08:52 PM

How are you operating the GAV when this is happening?

[email protected] · 10-30-2017, 08:54 PM

Quote:

Originally Posted by DJ S

I have this strange issue where my tudor will idle beautifully after just a few minutes of running but once it warms up to normal operating temperatures, the idle is extremely rough to the point where you think that the car might die on you. The car however does fine driving down the road and under load but once you stop at a stoplight, the car runs terribly. I also experience a hesitation in throttle response from idle. I'm thinking it might be a cracked intake manifold that is fine when the car is cold because the crack is retracted and not letting a whole lot of air in and when the car warms up, the crack expands allowing more air in creating a lean mixture. What are your thoughts?

My experience with cracks is just the opposite. Metal expands and closes the crack.

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steve s · 10-30-2017, 09:29 PM

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Click on "Search" above and enter "carburetor heimlich" under search posts, and find my description of the procedure.

I think your idle jet is plugged, and it can probably be easily cleared. Going down the road uses other jets.

Steve

DJ S · 10-30-2017, 09:37 PM

The idle jet can't be plugged because it wouldn't idle at all, hot or cold. GAV on start up is 3/4 of a turn open, after a few minutes I turn it down to 1/4 of a turn. The GAV doesn't effect the idle as it shouldn't.

steve s · 10-30-2017, 10:34 PM

Quote:

Originally Posted by DJ S

The idle jet can't be plugged because it wouldn't idle at all, hot or cold. GAV on start up is 3/4 of a turn open, after a few minutes I turn it down to 1/4 of a turn. The GAV doesn't effect the idle as it shouldn't.

I was guessing that he might have opened the throttle more during warm up, in which case other jets are in play. But, the GAV is certainly something that must be checked.

johnbuckley · 10-31-2017, 03:38 AM

Add to above ideas idle circuit over rich?- not enough air through idle air adjusting screw or idle jet orifice enlarged for some reason?

10-30-2017, 07:44 PM	#1
DJ S Senior Member Join Date: Aug 2014 Location: Southwick, MA Posts: 590	Rough Idle After Warmup I have this strange issue where my tudor will idle beautifully after just a few minutes of running but once it warms up to normal operating temperatures, the idle is extremely rough to the point where you think that the car might die on you. The car however does fine driving down the road and under load but once you stop at a stoplight, the car runs terribly. I also experience a hesitation in throttle response from idle. I'm thinking it might be a cracked intake manifold that is fine when the car is cold because the crack is retracted and not letting a whole lot of air in and when the car warms up, the crack expands allowing more air in creating a lean mixture. What are your thoughts?

10-30-2017, 08:20 PM	#2
1crosscut Senior Member Join Date: Feb 2011 Location: Lincoln, Nebraska Posts: 1,908	Re: Rough Idle After Warmup When it starts running rough spray starting fluid around the manifolds. If the rpm's change you have a leak. __________________ Dave / Lincoln Nebraska

10-30-2017, 08:35 PM	#3
Jacksonlll Senior Member Join Date: Jul 2012 Location: Michigan-- Member of Oakleaf of MARC Posts: 1,686	Re: Rough Idle After Warmup Also, make sure the flanges at the carb connection are flat and not leaking.

10-30-2017, 08:52 PM	#4
lindy williams Senior Member Join Date: May 2010 Posts: 335	Re: Rough Idle After Warmup How are you operating the GAV when this is happening?

10-30-2017, 09:29 PM	#6
steve s Senior Member Join Date: May 2010 Location: Kalamazoo Posts: 1,656	Re: Rough Idle After Warmup Sponsored Links (Register now to hide all advertisements) Click on "Search" above and enter "carburetor heimlich" under search posts, and find my description of the procedure. I think your idle jet is plugged, and it can probably be easily cleared. Going down the road uses other jets. Steve

10-30-2017, 09:37 PM	#7
DJ S Senior Member Join Date: Aug 2014 Location: Southwick, MA Posts: 590	Re: Rough Idle After Warmup The idle jet can't be plugged because it wouldn't idle at all, hot or cold. GAV on start up is 3/4 of a turn open, after a few minutes I turn it down to 1/4 of a turn. The GAV doesn't effect the idle as it shouldn't.

10-31-2017, 03:38 AM	#9
johnbuckley Senior Member Join Date: Jul 2010 Location: United Kingdom Posts: 1,441	Re: Rough Idle After Warmup Add to above ideas idle circuit over rich?- not enough air through idle air adjusting screw or idle jet orifice enlarged for some reason?