This is my first post, but I've read numerous posts and advice many of you have given and they really have helped me fix a couple of problems and I've learned a lot, so in advance thanks for the help. Now, I'm looking for some advice that I don't see or can't find others have had.
I have a 1966 Mustang L6 200 cid, auto, convertible I picked up last year and have tinkered with several things to make the car a daily driver, at least in the summer. You can't drive in the winter with a convertible here.
Earlier this summer I realized that I had the wrong carburetor on the car, which I assumed was one of the reason the car always ran rough, including fast idle, stalling at quick stops, etc. No matter what adjustments I did to the carb, it just wouldn't settle down, so after some research I found I had a carburetor for a manual transmission on the car (I have an automatic.) So, I purchased a new carb from Pony Carburetors. After installing the new carb it fired right up and I took it for a test drive to work out the timing a little more. After that drive, the carb was leaking from the accelerator pump shaft (under the bowl), but I didn't have time to investigate, so the next day I went back to check things out and the car won't start. So I assumed it was the carb, to make a long story short, I send the carb back and Pony fixed the carb up. I reinstalled the carb Pony send back and the car still won't start. I've checked the spark and I'm good; the coil is good, the plugs are good, I'm getting fuel in the carb. The car will occationally start for a couple of seconds, but then die, though it really never gets going. After the the initial 'start' it won't even do that again unless it sits over night and then it's the same thing. I've even replaced the points with a Pertronix II ignitor with the same results , (previously I was using the standard points). The engine turns over and sounds normal, no irregular sounds, pinging, dinging, etc. I do seem to be getting a little extra exhaust coming from the donut gasket as the manifold, but I didn't think that would cause the engine not to start.
I'm looking for some advice. I think it might be that the timing chain has jumped. Could a tooth or two slip be enough to cause this issue?
Thanks
1966 Mustang L6 200 cid Won't Start 
