Ignition gremlin where to start looking

Two possibilities: 43-yr-old ignition switches are known to electrically fail. Try a known-good one from another member (yes- some people do lend parts for trouble-shooting!)
Second choice- try a second coil. Can-of-oil coils are known to fail by burning the secondary windings inside where one cannot see them. When the can cools down (which may only take a minute or so), the burned wire ends may re-connect- until things get hot and the ends expand away and break the circuit again. For test purposes, ANY coil will work temporarily. If this turns out to be the problem, I suggest using a transformer-style E-coil in which the windings are exposed. They have been found to be far more insensitive to overheating.

I vote the ignitions switch.

Were you doing anything else when the engine died, i.e. operating an electrical device? Such as raising or lowering a window or turning on the head lights?

Well, as far as the ignition switch, I installed an "aftermarket" ignition switch from a hot rod shot and along with that I installed the Pantera Electronics Ignition switch controller last this last winter. (with push button start). I had the shut down problem before I replaced the ignition switch and controller thinking that would solve it. But no it didn't. So I don't think its the ignition switch.

How about this. I have one of my big electric fans for the radiator hard wired (with fuse) directly to the battery. It starts thermostatically. When it starts could this be pulling the voltage down far enough to starve the ignition box for a moment?

I go with Bosswrench, try another coil or be suspicious of the MSD 6 box.

I had a MSD box that would work, then not work and then work again. A lot of people had trouble with them.

Your MSD 8350 is a ready to run distributor so you can bypass the MSD 6 box and regap the plugs to verify operation.

Just curious..... Are you using an MSD Blaster 2F? I had a problem like that once and it ended up being the connection to the coil. I stopped using the 2F in favor of the blaster 2 which is more secure connection when used with ring terminals.

The MSD brain has a bad reputation for undependability. I had the shut off problem like you that was 40 year old electric grease that had hardened in the switch itself.

The MSD would just decide it wouldn't fire anything, then it would, then it wouldn't.

Don't know about their distributors. The coils seem to be decent, but the brains are disasters.

They seem to be affected by humidity as far as I can tell.

Personally have the P-E ignition controller, push button start, crane coil, Ford pointless distributor.

So far the ignition horror stories have all disappeared and have not returned.

Lots of voltage going through the original Pantera design of the ignition switch. If you were into that wiring to install the push button start, you need to verify that all of those connections are tight and the wiring is without trama from being handled.

Would be a good time to install the P-E ignition switch controller if you haven't already done so.

Still sounds exactly like a bad ignition switch and can't call enough attention to the undependability of the MSD system. Their harness for some inexplicable reason cause issues and the bad reputation of the brain is legendary.

Racers use them because of the contingency money. They also change them three or four times a year.

However it works out, I'd like to hear what you ultimately found.

On the P-E stuff, make sure your crimps on the wire "fastons" are tight and the tabs on the board aren't coming loose. One of my boards, the console switch controller, is currently being repaired for that. I guess I shouldn't hit it with a ball peen hammer?

Wow. Great info. Yes the MSD Box is 12 years old, in the engine compartment, be it on the bottom of the passenger side away from the headers.

I was first going to try an E core coil to see if that works. Its approx $40 so it may be a cheap attempt to solve the problem.

If that doesn't work, I will most likely change out the ignition box. But if not MSD, what's your suggest? Will it plug into the MSD distributor?

You don't think it has anything to do with a voltage drop when the radiator fan kicks on?

Thanks.

If my MSD6A ever craps out I'm switching to the P.E. Ignition, it looks like an awesome system.

So far it, combined with my Mallory Unilite Distributor, has worked flawlessly for 28 years. I've always carried a plug in wiring harness to bypass the MSD6A in case it ever messed up, but so far so good.

Now watch it screw up next time I'm out!!

The MSD 6A is a love/hate relationship. There are guys like you who have been running it for years with no problems and others (like me) who have gone through a lot of them before determining they are crap (my opinion based upon the 100% failure rate).

MSD Tech told me to buy someone else's product and complain to them and leave them alone. So I did.

Mostly Chevy guys running them here. The ones I know are just a bunch of numb nuts anyway.

Just my $0.02, I run ICE ignition on both Pantera and the Longchamp. Troublefree so far, and you can change the ignition curve and max rpm (2 steps) from your seat. The Pantera system is pretty race-like stuff, the Longchamp has the daily drive system with a vacuum signal going to the box, not the distributor.

Only problem is I haven't found a source outside Australia that stocks parts for it, so when I e.g. need a longer box-to-distributor wire, it takes weeks.

I've never heard of anyone else using ICE, if you're out there, step forward...

Make you a deal I just spent a month in CA working, even near Sacramento, if they call me back I will pack my msd 6 and let you try it out to se if it solves the trouble. I will know my schedule in about 2 weeks.

Hi everyone...an update. I replaced the MSD Blaster 2 coil with the MSD Blaster SS coil E-type (part #8207), about $50 from Summit.

Well after 3 trips around town, stop and go the gremlin seems to have disappeared. But as I said the shut off problem was so intermittent, I don't know if I solved the problem, but for now it seems to be the fix.

Note: when I took out the Blaster 2 coil I noticed that the outside casing of the coil was slightly crimped by the bracket. Maybe the slight crimp did something to the internals of the coil?

I'll post an update if the problem returns or appears to have been fixed for good. Thanks to all for your comments.