make sure you are timed correctly.. it takes some time to get it tuned perfectly unless you are 100+ years experienced.. i know when i timed mine to a 'perfect' set up it ran like garbage and never wanted to start after being warmed up.. one of those things i suppose... also do you have an electronic fuel pump? or manual..

 

Does the small red wire on the MSD get 12 volts while you are cranking?

 

The fuel pump is mechanical and the red MSD wire i will have to check

 

If the MSD is under the dash you can tap into the crank wire on the key switch with a diode and hook that to the red wire too (dont disconnect where its hooked up now) or if its under the hood tap into the starter solenoid #10 stud thats next to the heavy wire that goes to the starter.

 

does it crank over at normal speed or lug down and crank slow? if it cranks over at normal speed next time try holding gas pedal to floor and crank. if that does the trick ur carb is leaking fuel into intake after shutoff and carb needs work. if it cranks slow u probably have dirty battery and ground cable connections. wes

 

The car turns over fine and I have tried numerous ways (gas, no gas, half pedal, different numbers of pumps to the pedal before, during, and after I turn the key etc) It just cant seem to fire up after getting warmed up.

 

IMHO...

1. ignition (e-boxes don't like heat)
2. vacume leak (intake manifold)
3. hot fuel in the fuel bowl (installed a heat shield at the base of the carb- this is nothing more than a piece of tin that installs at the carb base and sticks out to the shape of the carb)

 

Does it blow black smoke when it finally fires up? Have you check the ignition coil?

 

I would bet it is hot fuel in the bowl. That is a very common problem with our mustangs. If you don't have an insulator gasket from Holley, I would suggest you get one. Also, make sure the float level is correct. High float level can make the hot fuel problem worse.

 

Ignition coil is an MSD Blaster (I actually have 2 and I swapped them out on 1 of the occasions when it was refusing to start). This did not work either, also no black smoke when it finally does start up. I will be checking some of the other suggestions tomorow.I also have a composite carb spacer from Summit racing that went with a summit carb I sent back. This will probably work as a heat shield for the Holley?

 

Check to make sure you have spark when cranking too.

 

carburators can be tricky.. definitely check those float levels!!! I know I had to replace my e-ignition.. when I did I had the spacing wrong and it didn't want to start up.. you may want to check that (maybe it's just barely off).. worth a shot if everything else checks out...