Hello all
I have a 1967 Ford F-800 with 15000 original miles, it was a fire truck up untill 5 years ago, now it makes a great service truck for the farm. However it was going good i tuned the truck up when i got it, new plugs wires cap rotor, points. i have put 10000 miles on the truck and it never missed a lick. however now when the truck gets warmed it starts missing and wont run at hight rpm under a load, i thought it was the fuel pump but i got good pressure and plenty of volume out of it, so i have decided that th coil is breaking down, i have tried every coil that i can get my hands on, from the auto parts stores and even the dealer. but with a new coil on the truck it wont even start, but it will as long as the original coil is on there. my question is what coil do i need, and why does the negative side of the coil go to ground. Is it possible to fix this transistorized ignition system or am i going to have to got back to a points and condinser system.
the engine is a 391 with a holly 4 barrel and a clark 5 speed with a 2 speed rear axle. it runs 60 mph against the goverenor at 3600 rpms, but it sure sounds sweet with those dual staight pipes turned out the side.
thanks for any help guys
Shawn

 

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I've never heard of grounding the neg post of the coil unless you have a secret switch to prevent it from starting. The - post should go to the Dizzy and maybe a tach if you have one.

Keith