Engine randomly cutting out, why??

Wondering if somebody could steer me in the right direction here. I have a 1970 GTX street strip car. It has a 451, 12-1 compression, solid roller, 440-1 heads, and all the other matching stuff, and runs high 10's. Been more doing more street driving with it lately, and having a strange issue with the engine just killing on me sometimes. It usually happens after the 1st 10-15 minutes of driving. The car will run fine, and while I'm just cruising, the engine will just die, making a noise like its dieseling when it dies. I then pull over, and it usually takes about 30-60 secs to get it restarted, and then runs fine after that.

This problem started last fall, and the car had an old out of the box 1050 dominator carb. I figured it was the carb, so I bought a 1000hp carb from pro systems. Wanted a more streetable carb anyway. The car runs awesome with this new carb, but still has this issue, so I don't believe its the carb. When it does this, I never had the time to pull over and diagnose things, as I'm in traffic when this occurs. Strange thing is the car runs awesome pretty much all the time, and when this occurs, there is no warning. Its frustrating, as I'm not trusting the car anymore to take it places. Went to a friends party last night, and after 10 minutes of leaving, it did it again, and I was 30 miles from home. Took me a few minutes to get it restarted, and ran perfect the rest of the way.

I'm running a fuel cell in the trunk, and using 93 octane pump gas. I'm leaning towards a vapor lock or fuel percolation issue. If anybody has any advice to my problem, would love to hear from ya, thanks!

You are running a 12.1 engine on 93 pump ???

I would look at your fuel, what do you have a for a fuel pump , if electric can you here a change in the sound of the pump when this occurs ?

Fuel pressure gauge ???

There could also be an issue with wiring going thru the bulkhead if the wiring is still original and you have the factory ammeter still in play ?

Well, just as I posted my topic, it did it again. Went to move some cars to get it in the garage. Started right up, and parked it in the street and left it running. Ran for 2-3 mins, and died. Would not restart again for 20 mins. Just cranked and cranked, like it had no spark. I'm thinking now its an ignition issue.

JohnRR, I should of been more specific, my motor is close to 12.1. That's what I was told when I bought all the parts from Indy cylinder head a long time ago. Exact compression, I do not know for sure. It doesn't ping or detonate on 93 octane, and I run locked timing at 36 degrees. Like I said, the car runs strong and nice. I'm sure I would benefit from better gas, but my main concern is this cutting out problem. I have an old Paxton 300 electric fuel pump running 7 psi of fuel pressure. Pump still runs well and doesn't cut out. I upgraded to a 120 amp denso alternator years back, upgraded the wiring and no longer use the factory ammeter.

I'm thinking its now an ignition problem. I have an MSD pro billet distributer, 7al2 ignition box, and an older blaster 2 coil. Looks like I'm going to have to test all this stuff and go through my wiring. Wont be driving it until is fixed, don't wanna be stranded and its not safe if it dies at any time. Wish me luck....

Did you check to see if it had no spark rather than assume?

Did you pull the air cleaner and see if it squirted any gas when you worked the throttle?

We can't do these things for you and until you know what is missing from the equation you'll spend a lot of money on it.

I wasn't able to test for spark at the time today when it acted up, due to it blocking the street. The carb was working as it should, with fuel coming out of squirters when throttle was pressed. I'm going to mess with it later, let it run and hopefully it acts up again and do some testing, now that I got it in the garage.

Get a spark plug and keep it handy for next time it acts up, pull a plug wire, pop in the spark plug, ground the case and see if it sparks when cranking, but based on it having gas coming out the squirters I'd lean towards an ignition issue with you.

Yep, I was about to guess fuel "vapor lock" from a hot carburetor or fuel line too close to headers.....but then the carb would be bone dry..... so yes, I'd have to go with ignition. Maybe an ignition control box or coil about to go bad?

I bet on the coil or the ignition box Said this before MSD and street driving ? high heat is a real problem and the ignitor coils are anything but good when real hot

I agree, can you borrow a coil off of one of your other vehicles? You'll confirm or elim that in an hour

I had a 69 Chrysler that would do this from time to time. I about pulled my hair out. Finally, just that 1 time I was ready when it happened. jiggling the wires made it start again. Believe it or not, I was loosing the ignition connection through the firewall bulkhead connector. Apparently I was loosing the connection if I hit a bump on the road just right.

I pushed all the wires into the bulkhead connection with a small screw driver from each side of the bulkhead connector and completely solved the issue.

Its a zero dollar fix to give a try. You could also have a lot of corrosion between the connections at the bulkhead connector that would cause the same issue. Gene

Its had the same 7al box and blaster 3 coil on it for I bet 13 years now. Time to test those. Really started street driving it a lot the past 2 years. Before that, it would see maybe 100 miles a year on the street. Looking at my engine harness, I think its the original one. This is going to kick myself in the rear and going to get a new one of those. Its seen better days. Now I just need this hot weather to stop for I can work on it.