I got a 78 F100 a 514 in it and just got finished installing a MSD 6A ignition box, Blaster SS coil, and Pro Billet distributor now i cant get it to start it ran with the old distributor and stock ignition but I needed better fire. Its getting plenty of fire and fuel and has been put back to TDC and firing order is correct Ive triple check everything I pulled the number 1 plug out to see if it was getting fire and went to turn it over and the truck fired up with the number 1 plug out of the cylinder. I have no idea what is going on and need some help on this problem. Thanks

 

Did you put the plug back in and try it?

 

Yea but still nothing when it started with the #1 plug out I used the screw driver method on the starter solenoid since I was by myself maybe it has something to do with stock ignition wires not plugged into anything?

 

I don't understand what you're saying. You're saying the truck runs with the #1 plug removed from the engine, but not otherwise? Please use more punctuation.

 

Yea that's what I'm saying, I had the #1 plug out of the engine with the plug wire attached to the #1 plug to check the spark, then turned the engine over by touching the solenoid with a screw driver and the ignition on, when I did that the engine started up. I quickly shut the engine off and put the #1 plug back in the engine and tried to start the engine and it would not fire up. That's as simple and plain as I can put it anybody know what might be going on with that?

 

There are only two explanations for what you're seeing:

1) You have some sort of odd cross-firing issue, having to do with plug gap, broken coil tower, or bad wires - such that the added path to ground somehow breaks it. I have never heard of this happening.

2) Something else is going on that you're not aware of or not making clear in your description of the problem.

 

I'll just call MSD in the morning I can't explain it anymore than that, I followed instructions, everything is new, plug wires have layed around a while but are new, motor is at tdc. I thought someone might know on here.

 

You jumped the solenoid , and it started . It won't start with the key . Is that correct ? Sounds like you are loosing power to ignition while in start position . Try jumping solenoid with plug in and ignition on . If it starts , you are dropping power while key is in start .

 

bingo jwc3 he no longer has a start circuit for his ignition.

 

Thanks I wouldn't have thought about that I'll try it in the morning thanks for the info JWC 3

 

If it is dropping power how would I fix that?

 

You need a wiring diagram , a multimeter or test light . You should have power supply to ignition from switch while in run and start . I think you are loosing it in start . With a wiring diag . you can trace it down .

 

Thanks I'll get on that in the morning

 

Bingo. There were more variables than just the spark plug being in or out. The spark plug was just a red herring. Looks like it was #2:

 

It is something to do with the key switch truck started right up with the solenoid and ran so I got it put in time, but I don't know were to start trying to figure that problem out, could I just put in a whole new switch or do I need to trace down wires?