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1971 3/4 ton camper special. Did a full tune up points, condenser, cap, rotar. Now somewhere down the road some one has installed a 1979 360 with points dist. Truck ran good befor tune up now it cranks over but wont start. Spark at the coil, points and plug wires ,have fuel. Put all the old parts back in and still no start. Checked the fuses all ok. Any help at all would be great. Thanx Mark

Did you set the point gap and check the timing? Make sure that the rotor is pointing to the #1 terminal on the cap when the motor is at tdc on the compression stroke. Not on the exhaust stroke. Remove the #1 spark plug, turn the motor with a wrench or by the fan as you hold your thumb over the spark plug hole. When it builds pressure and pushes air out past your thumb, you are on the compression stroke. Continue rotating until it is at tdc. Then look and see where the rotor is pointing. Good luck, Joel

Bin there done that. Could it be my starter relay. or a dist or run start circuit?

if your starter relay was bad then she would not crank over

if she was running well before, and you have fuel and spark right now,
maybe you disturbed the timing when working on the distributor ?
seems like good advice to double check the static timing and try again from there

or maybe the ballast resistor or its wiring got futzed up when replacing evrything and the coil is not getting the full 12V during startup ??

I had a 360 once that sheered the tang off the distributor. All I had done is drive to a store and when I tried to leave it would not start. Try as I might I was baffled for a week until I cranked the engine with the cap off and noticed the rotor was not spinning. Good luck.

I don't have 12 volts going to the coil on the dist side. What would cause this? It only shows 5.6 volts. Rotor turns when cranked. Dist is tight so I dont think timing is out. With #1 at tdc timing mark sits at 10 degrees. Could there be a short in the dist? I will check the ballasl wires tomorrow.

Spark at the coil, points and plug wires ,have fuel.

Your original post says you have spark at the coil, and it is unclear if you have spark at the plugs, or if you are saying that you have new points plugs. If you have spark at the coil, why are you checking voltage? I want to help, but need more complete, clear and consistent information.

the ballast resistor should be reducing the voltage during running but it should be wired to pass the full 12V during startup only
to protect the coil

Trucks running great now with a new set of plugs.

morbert wrote:1971 3/4 ton camper special. Did a full tune up points, condenser, cap, rotar. Now somewhere down the road some one has installed a 1979 360 with points dist. Truck ran good befor tune up now it cranks over but wont start. Spark at the coil, points and plug wires ,have fuel. Put all the old parts back in and still no start. Checked the fuses all ok. Any help at all would be great. Thanx Mark

Wasn't a "full tune up". That also requires new plugs and wires at a minimum.