51 ford flatty, ran fine till last weekend. i put in a new radiator and new plugs and wires. plugs gapped same as old plugs. car runs great till it gets to about 170 degrees, then at about half throttle to wide open throttle starts breaking up like its starved for fuel.... cleaned the carbs (two ford 94s recently rebuilt), new fuel filter, has electric fuel pump thats been on it for a year now, cars 12volt with petronix thats 6 months old, in original dist., timing hasnt changed, plugs look ok... any ideas?
run it till it starts messing up and check for fuel,, I would imagine that it is ignition related, coil breaking down or the pertronix unit is overheating.
Check fuel pump. Get a fuel psi gauge and tap it in the line. The Petronix is doing it's job. The fuel is burning better and more efficient. So it might be starving.
a engine that is running out of spark will sometimes act just like one with fuel problems. Except when it is starving for gas it usually runs lean and belches back through the carb. OldWolf
You say it breaks up at half throttle when warmed up, if that means it breaks up over 2500 to 2800 RPMs, I would change the plugs. If it has Champions, go to the Autolite 216 or the NGK B6L. Gap them to .030 and try it again. I had a set of Champions with less than 100 miles on them do just what you said. The NGK's are great. The Pertronix takes the place of the points, it cant create a stronger spark without a better coil.
If it ran fairly decent with the old plugs and you haven't thrown them away yet, stick them back in and see what happens. The coil might be breaking down too though. If you have another one sitting around you might try that if the plug swap doesn't produce results. <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
Try it without any air cleaners on it. You got the little hot rod ones on it ? if so they get a bit dirty it will give simular symtoms.
I would check the new wires also, I have had a bad experiance with new wires and one of them was bad. It would idle ok but as soon as I would get up in the RPM's it would shudder and I would have no throttle. I would check the resistance. Were you having problems to begin with is that why you changed everything?
The heat issue makes me suspect the condenser first, then coil. Other suggestions above are good also.
Check the rubber fuel line, if you still have it, mine looked fine but was all messed up inside, think it was from the newer gas.
Sounds electrical , so I would change the condenser first because it's cheap . Have seen many that were NEW and didn't work at all . Might be what I called a Hot & Cold coil ! When the coil get hot it breaks down . See if you can get a used coil from somebody to test with . As long as it's getting gas , it should start with good electrical parts . RetroJim
I take back my first reply. I recall a time I had the same issue you are having. It might be the spark plug wires. I lost a good street race cause of it. It would launch hard off the line and would sputter before it peaked to the high RPM's. It was night time so I popped the hood open. Engine running. I rev'd the engine up and saw that all the spark plug wires were arcing all over the freaken engine. Pissed me off! That was the first and last time i've ever used ACCEL products.
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