I have a 83 F250 460 auto with a Summit cam #K3501 and roller timing chain installed straight up. My problem is that some days it acts like i have a staging rev limiter installed. Feels like its firing on every other cylinder till you reach 1200-1500 rpm (sorry no tach) which makes for a difficult time to back up and turn around with a trailer. Once it is above that rpm it runs fine. It does it warm or cold. Then it decides to run and will idle somewhat sooth and work like theres nothing wrong. I am thinking that it may be the pickup coil? I also tried replacing the ignition module but it made no diference(maybe bad also).
Thanks for your help
GENE

 

Are you sure what you have is an ignition related problem? If your plugs are in good shape, inspect your wires, spray them down with a spray bottle of water (should not miss). Is your cap good, are there any carbon tracks? Your rotor may also be shorting to the distributer shaft. The distributer pickup may even be faulty. The ignition system on your truck is pretty simple so you should be able to check over all these things in 1/2 an hour or so. Try and eliminate parts by testing, and inspecting them.

Also don't dismiss your fuel system as the culprit. Is your choke working properly? Is your EGR valve coming on too much? Go over everything and fix anything questionable.

Sorry I can't put my finger on it for you, if I could I would be able to rule the world. Anyways hope this helps, let us know how it turns out so we can learn from your frustrations.

 

Installed new cap,plug wires and rotor didnt fix!
Installed new ignition module didnt fix!
Installed new coil BINGO!
Will test for a couple of days before feeling at ease because of being a intermitent problem.
GENE