84 F250 460 2wd Auto

A short history:
Orig owner. 150k mi. Some years ago developed a hard/slow turn over/no start problem after reaching operating temp. Typical deal, wait 15-30 mins and starts up nice as you please. Cold starts were fine.

Current history:
Just rebuilt engine. 9:1 comp, stk dist., stock heads,blah, blah.
10 deg. initial timing.
NEW 800 ca battery, starter, alt, coil, starter relay, 2 ga. battery/starter/ground cables, ign. module.
Grounds run from battery to block and block to frame.
Still having the same issue.

Disconnected the R/LB starter wire from the solenoid, connected a bump switch between that terminal on the solenoid and the battery terminal on the solenoid and it turns over just fine.
WTF?

Reinstalled the old parts(starter, solenoid etc) and did the same thing. Turns over just fine.

Went back to the new stuff and repeated. Turns over just fine when jumped.

Could it be the ignition switch? That and the wiring which supplies power to the switch are the only things that have not been replaced.

BTW I have tried a different eng/ start harness... still no change.

I have posted this in the 1980-86 forum as well.

Any Ideas...Thanks

 

I would like to know as well. I have a similar problem in my 93 460.

 

Hey welcome to the community!
If you look over in the 1980-1986 forum you can see the progress, or lack thereof, of my plight.
I should be posting more progress, or lack thereof, later today.

 

Wahoo!!! It was the ignition switch. Turns out one of the terminals on the switch was minutely loose. Just enough to allow voltage to drop below useful.