78 f250 460 hard hot start?


alwaysFlOoReD

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I recently refurbished a 79 460 and transplanted it into a 78 f250 4x4 for a friend. It fires up fine when cold. Once warmed up it acts like there is very high friction, it rotates enough to get to the next cylinder and stops.
I put in a new crank, new mains and rod bearings, new oil pump, new Cloyes roller timing chain and gear keyed to advance the cam back to a straight up config, new water pump, new aluminum intake and used but basically new aftermarket 4bbl carb off the 400ci. Also new starter and battery. The transmission was rebuilt by a reputable shop.

I'm wondering if I advanced the cam incorrectly causing problems with too high compression?

Any other possibilities to check?
 


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RonD

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Disconnect coil wire to take spark out of the equation and see if starter motor can crank engine over when warm.
If spark is happening to far BTDC it can stop engine cranking, same can happen with pre-ignition if using regular gas and high compression, but you would probably have "run on" or "dieseling" when shutting off warm engine if that were the case

Could be starter motor or battery cables have increased resistance when warm so not enough AMPS in the system
As we all know, "new" just means "never tested before", lol
 
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fangotango306

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We had a 390 FE do exactly what your talking about with a new crankshaft. Crankshaft end play wasnt checked properly and when the motor got warm the thrust bearing was too tight and caused a bind. Had to tear it down and face grind the vertical bearing lands on both sides of the thrust journal. Hope you dont have the same headache.
 

fangotango306

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Also to eliminate compression as a possibility. Get it hot and pull the plugs and crank it over. It should spin over freely.
 
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alwaysFlOoReD

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Thanks for the input. I'll be looking into this on the weekend.
 

rusty ol ranger

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I had a 89 F250 with a 78 lincoln 460 that did the same thing...

Turns out the headers were cooking the starter with heat. If hes running headers try wrapping them, took care of mine.
 

alwaysFlOoReD

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Looks like it was a weak starter. It got replaced and no more problem.
Thanks for the input.
 


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