351C and MSD ignition problem

[dfayette]

I installed an MSD ready-to-run 8350 distributor on a 351C. The bottom end is stock, top end is comp cams 292H cam, roller rockers, 4V quench heads modified for the rockers, Holler 670 street avenger and the MSD ignition.
Engine cranks well and fires right up. I release the starter and the motor dies. I find 12v at both pos and neg of coil which makes it die I'm guessing. I can't find any troubleshooting tips for the distributor to see if it should really be putting 12v at both sides of the coil, but my thinking is that the negative side should not be equal to the positive side if I want it to run.
Anybody have any troubleshooting tips for this ignition? Wondering if I should just go with the ignition module and see if that fixes it.
Thanks.

 

[woodsnake]

Does your car have a factory tachometer? Did your set up come with an instruction sheet? Not to sound snarky, but there are a few choices on how to wire the car, on the instructions. Check the MSD website, they should be available there to look at...

 

[dfayette]

Does your car have a factory tachometer? Did your set up come with an instruction sheet? Not to sound snarky, but there are a few choices on how to wire the car, on the instructions. Check the MSD website, they should be available there to look at...

No factory tach. Followed the instruction sheet. There are two drawings - one without ignition module, and one with. Checked troubleshooting with MSD but they have not replied yet.
I suspect the distributor is bad but need a way to prove the pickup module is putting 12v on the negative side incorrectly, or prove that it is and that something else is wrong.

Thanks

 

[Hack]

It really sounds like you wired it wrong to me. The distributor would not be able to make a ground source (-) read 12v. If there is ground on one end of the wire the whole wire will read near as makes no difference to 0 volts. I think you must have wired a 12v source to the distributor ground.

 

[horseballz]

dfayette,
The fact that you say:
"Engine cranks well and fires right up. I release the starter and the motor dies."
tells us that the distributor and MSD box (if its hooked up) must be working, but you likely have the "power on" feed hooked up incorrectly. On the original wiring, the wire to the coil is fed from 2 different places:
1>From the "run" terminal of the ignition switch, through a resistor wire, giving you 6-ish volts at the coil during normal running/operation.
2>From the small terminal on the starter wire side of the solenoid, giving you a full 12 volts at the coil "ONLY" when the starter is engaged.
These 2 feeds "Y" together somewhere in the harness. It sounds as if you are only hooked up to the feed coming from the solenoid, thus your issue
HTH,
Gene.

 

[dfayette]

For anyone interested - the MSD distributor was returned for repair. They replaced the PC board in the distributor.
Proof of failure was installing a stock distributor and the engine starting right up and running.

 

[woodsnake]

Cool, thanks for posting the fix! Most of the time these threads go open ended..