Need ignition advice......
 

I have a '61 wagon w/stock 455 and TH-400. I am using an HEI from mid '70's (I think) I have it directly wired to the keyed side of the fuse panel. During the first week, probably 25 years ago, the little sheetmetal module thingy with one wire on one end and two on the other failed. I dont know how I knew that was the problem, but putting another used one in cured it. It has started many times instantly since then........

This past week we went to the last car show in the park. Started it several times in the course of going, stopping for breakfast, letting her out, etc. However, when we got ready to leave 7 hours later, it hit instantly, didnt run, then wouldnt hit after that. Tried several times. By the time I raised the hood, borrowed a screwdriver to jump a spark from a wire to some ground, it started. Has started several times since.

Now I cant trust it....... It will become an estate item pretty soon. I need some for sure cure before that.

Whadda ya think I should do...????

PJH

" During the first week, probably 25 years ago, the little sheetmetal module thingy with one wire on one end and two on the other failed. I dont know how I knew that was the problem"

Picture of "sheetmetal module thingy" ?

A a start, check your power connections.

George

HEI modules are known to WORK ...or NOT WORK! no in-between...no warning.....Thats why it is usually the first thing folks go to when the ignition fails. Check all connections (little ground wire in center of the 3 wires going to the coil ;) and then DRIVE IT.....use it....make it earn your trust back by USING it. Yeah its a hard thing to NOT trust if this is a 10 minute run to the grocery store or....2 hrs cause it will not restart...
OR
Spend $150 replace everything in/on dizzy ....move on

If it restarts after time then it's not the pickup module because whenever I have had one of those fail it never came back to life because they develope a very very fine wire that breaks.

This then leaves the ignition module that I would say with darn good certainty is going intermittent on you.

The bright side of this is that the ignition module can be replaced with the Dizzy in the motor where as the pickup coil can not!

given its LONG life of use.... if no connections prove to be "suspect" you might try removing the hei module ...clean it...apply NEW thermal grease to the underside...and reinstall....sometimes after 20-30-50 yrs....lol it sorta hardens up and becomes less of a heatsink. HEI HATES heat.

If you want your heirs (or whoever picks it up at the estate sale) to have no problems with it for the next 25 years, get a D.U.I.

Extremely high quality, great customer service, affordable, easy.

https://performancedistributors.com/...-distributors/

Yep Yep
 

That part description got me stumped.

Almost, but not quite, thinking OP might have a unitized distributor instead of HEI.

I've worked on a few old cars with tired ignition switches. How far or how hard you twisted the key, determined if the engine would fire up or just have starter spin.

Clay

The 4-prong HEI module has chips in it that should last more than 1000 years. Heat considered, the life is about 200 years.

Therefore, check the pickup coil for continuity. Those pickup wire break from VACUUM ADVANCE movement.

Take a spark plug with you and next time it happens, put a plug wire on it, lay it on the frame and try to start it.

I have NO IDEA what that is.
Yes, please.
Much better: An actual spark-tester, calibrated for HEI ignition. Point the sparking end towards the driver's seat, so you can see it while cranking.
https://www.amazon.com/dp/B003WZXAWK...v_ov_lig_dp_it
https://m.media-amazon.com/images/I/...AC_SL1500_.jpg

My spark plug thing wasn't to check spark, might be a grounding thing, I don't know. I had a 79 TA that would do the same thing heckinohio's car did. I had to shut it off at the drive thru to order food, most of the time it would restart, sometimes it wouldn't. It might not start after sitting 4 hours, might start right up, hot, cold, didn't matter, there was no pattern to it. I removed a plug once to check for spark and it started right up, put the plug back in and away I went. I kept a spare plug with me after that and it would always start when I grounded the plug and turned it over... A roommate I had back in the same time period bought a newer mustang. We went to the convenience store and came back out and it wouldn't start... Weird since it was only a couple years old, if that. I tried the spark plug thing and it started right up. That was the only time he had that problem as long as I knew him though.

What's the difference between spark plugs grounding on the frame, versus spark plugs grounding in the cylinder head?

Maybe the engine wasn't grounded good enough? I have no idea, might not even be a grounding issue? I'm just saying what I found to work when I was having the same issue as the OP. I have no idea what caused the issue and no idea why it was so sporadic. All I know is what worked for me and that I always drove it back home.