galaxie198

Hello I have a 66 mustang GT 289 4 V IT runs good but when warms up it runs rough and stalls,I changed everything in the electric system dis cap, rotor, plugs, wires, coil, just rebuilt carb,voltage reg Fuel pump presser is 4 to 6 pounds of presser, car been completely restored even the engine which only has about 10,000 miles on it. Anybody with answer please help me running out of ideas..

Chromeshadow

The first thing I would do is replace the old distributor and go to a totally electronic ignition.
The other thing I would check-when a carb engine is cold, it has to run rich. It needs to lean out as it warms up. If it's a fuel problem, it could be a vacuum leak or the choke is not opening, or the carb is tuned to run rich all the time. This is easy to diagnose, put a white rag over the exhaust pipe-if it turns black you are running too rich. You can also look at the plugs, they should be tan. If they are black or greasy, you are running rich. If they are very light tan or white, you are running lean.

99GTvert

Moving thread to Classic Tech..

Starfury

I agree that you should look at the choke to make sure it's working properly. If the choke is not properly adjusted and remains partially closed when the car warms up, you'll get exactly the symptoms you're describing.

Also, make sure there are no vacuum leaks. Spray a bit of brake cleaner around potential vacuum leak points (intake gaskets, carb spacer, etc) and listen for the rpm's to pick up. If they do, you've found a leak.

galaxie198

Hello
I read that a 65-66 mustang has a resistor wire in the system when using pertronix instead of points it need a full 12 volts in run position, voltage through the resistor wire is 7-9 volts, it needs a full 12 v in run position if I am right Will have to bypass that wire and get a full 12 v to the coil in run p.

Gun Jam

when did it last run right?

other than whats listed above did anything change?

galaxie198

It started running bad about 3 to 4 weeks ago, but slowly ,then got real worse a week ago. It has to elect with the pertronix from what I been reading.It would run great when cold ,as it warms up is when it starts to run like crap and hard to start when turned off.

Starfury

Definitely bypass the resistor wire; I bet it helps quite a bit.

galaxie198

Well bypass the res wire unplugged wire from ins switch and ran new wire 14 gauge with fuse link in wire car runs runs like a 66 mustang GTfrom California like it should.... Thanks