Hi I have a 72 F250 4x4 that the previous owner swapped a 460 into. The year of the motor is unknown but it has a carter afb carb and a points distributor. The truck will run fine for anywhere between 10 to 20 min then will start cutting out like its running out of fuel, die, then when i go to restart it cranks very slowly like a dead battery and is very hard to restart. a few times i had to jump it to get it going again. I have load tested the battery, and also checked the charging system and both check great. Battery voltage is between 13.5v and 14v while running and around 11.5 to 11.7 while cranking. I really dont know what the problem is. Has anyone else ran into this or have any ideas? BTW sorry for the long post. Thank You

 

you may have more than one problem.

the slow cranking sounds like your timing is too advanced.
but- that wouldn't cause the engine to stall.

here's what i would do:
check the timing.
let the engine run until it stalls
then immediately check the fuel level in the carb

if you've got fuel, then we'll start checking the electrical.

 

Timing is 10* btdc, engine runs at idle for what would seem like all day long, while driving cold all the power in the world at all rpms, after 20min anything over about 2000 to 2500 and it starts cutting like out of fuel or if going up hill same thing. And then with no warning it will just bog down quickly stall and die, then no start with very slow cranking like dead battery.
Would a bad coil or condensor when heated up cause timing to jump and cause this? I think youre right though i think i have multiple problems, cause when running normal it does have a miss and hesitation off idle. Im sure it needs a tune up, plugs wires cap rotor points condensor and fuel filter. But this stall then dead problem has me worried and its left me stranded twice now so unreliable right now.

 

how hot is it under the hood? how close does the exhaust run to the starter? as far as the truck stalling, my car had an issue close to that...it was boiling gas out of the bowl vent and flooding the motor out.....for the slow start, maybe the starter is just too hot to spin at it's normal speed....then again, it could be neither of these....park the truck, start it, and remove the air filter, then run it until it stalls, just to see if its boiling over or not

 

a bad coil/condenser wouldn't cause the timing to jump.
however- a bad coil COULD start cutting out on you.

since you say the motor was swapped in by someone else- i'd check voltage at the coil + with the engine running. i wonder if the PO removed the resistor, and the coil is overheating.

 

I'd also rebuild the carb. I had a similar problem with my 69 360. Rebuild kit was 16$ and 1 day later runs like a top. Well worth the time and money. My float was way low and carb was full of crap clogging it up causing the stall.

 

ok thanks guys the coil thought sounds likely as well as the carb rebuild, it does seem to run like starving for fuel. I will have to check it out and see what i come up with ive been focusing most of my attention on my mustang but if i have time tomorrow i will work on the truck