Runs with Choke on, but not when choke off

[71killshot]

Hello all, I have recently gotten my 71 Stang up and running again after having it sit for about 3 years. Well atleast it runs for a little bit and then it starts to have some issues. I have replaced the intake and carb with a Jegs intake and a Edelbrock 500cfm 4 barrel carb. The issue I am having is that when the choke is on while warming up it runs just fine, but as soon as the choke shuts off the idle drops down and begins to stall out. If i give it more fuel the revs pick up and it will stay running. I though maybe this was a idle issue so I ran the idle screw in only to have the rpms jump way up and then have it die out again.  I have set the timing at 10 deg from 6 thinking that was the issue but it didnt help at all.

While trying to drive it I have to two foot it at a stop light, if I let off the accelerator it will die out. Any help will be greatly appreciated in getting this car back on the road.

 

[OzCoupe72]

Might be a silly question but have you adjusted the idle mixture screw? the small screw on the metering block. Usually start with screw it in all the way but NOT tight then back out 1 1/2 turns, run engine then get the idle smooth or screw it in until nearly stalls then screw it out counting the turns until it nearly stalls, then screw back in half of this number should get it pretty good. hope this helps.

 

[computercarguy]

I would also check for a vacuum leak.

 

[Don C]

+1 on the vacuum leak, not easy to get the intake manifold seated properly with no leaks. Also make sure there aren't any open holes in the carburetor and manifiod where vacuum lines, PCV valve, EGR, etc are supposed to be connected. Is the PCV connected and functioning? Power brake booster connected and not leaking?

 

[rvrtrash]

I would check for a vacuum leak as well. Plug all your vac ports at the manifold and see if the problem goes away. That eliminates the accessories downstream.

Steve

 

[71 mach1]

Sounds like a vacuum leak spray the base of your carb with brake clean or carb cleaner and also around your intake gasket ( sides and on the ends ) and listen for rpm increase this will show you if and where your sucking air which is more noticeable at lower ( @ idle ) rpm

 

[71killshot]

Turns out I had a vacuum leak on top of the hose tree and my timing was way off. I thought it was 10 deg but I guess not. Now that the leak is plugged and the timing is right it seems to be running better. Thanks for the input all.

 

[Studdley]

Compression check that sob