XMWZ001

Good morning everyone,

Back again for some questions. As a few of you know, last summer I installed a new Hei on my new motor and had some resistor wire issues. Once I replaced the wire with a true 12v source all was good for the rest of the summer. Now that the weather is nice I have been getting the car out. Over the winter in installed an older sun-pro tach I had lying around and that was the only thing ive changed on the car. So I started having the same problems as before, the car started randomly dying and I am 100% positive it is not fuel related. Let me explain what I have done as soon as the car started to die.

-Unhooked my tachometer (thinking maybe it was ground issue with the tach) However the car would still die.
-12v power to Hei (while running)
-12v cranking power to Hei
-Pulled the module to have it tested and found out the module was bad.
-Bought a new module and installed (with using white heat sink compound)

Then the car fires right back up. But it sounds as though it has a miss to it. You can watch the tach and it every now and then it will drop to about 650 rpm from 850 and go right back up but not consistantly.So I go on my merry way driving for a week. Friday night Im taking my girlfriend out for dinner and what do you know........middle of traffic downtown the car cuts out and dies. I roll it into a parking lot. Over 30 minutes and still wont start. I then..

-Pulled the cap to check for abnormalities (aka loose ground wire) and cant find anything out of the ordinary.
-Get towed home on a flatbed by AAA.

What do you think the culprit is here? I am losing my mind on this deal here. To me everything points to maybe coil failure? Wiping out a new module in a week? Now I was out of town sat and sunday so I never got a chance to try and check for spark but my gut feeling is there wont be any. I tried to do my best at explaining this, thank you all for taking the time to read and hopefully give me some thoughts and tips. Cheers

BILL DEMMER

i'd start with a replacement ignition coil. a bad coil will smoke a module pretty quick.
after that, the only things left are the pickup coil(and it's wiring) and the wires running from the body to the cap. i assume all of your wiring connections are clean and tight.

bill

redoldsman

I think Bill summed it up pretty good but what about the girlfriend?

MDchanic

Did you have the new module tested when you bought it?

I always do, and just last summer had the new one test bad, just like the old one did. Had to go to another store to finally find a new one that tested good.

Why did you switch to HEI again?

- Eric

redoldsman

Thank You China.

goodkarmech

You didn't mention the rotor... I've seen these go bad & they look fine but the spark will pass right through the plastic grounding out on the distributor shaft. I've also seen wires come loose from the pickup coil. This rotates back and forth with the actuation & release of the vacuum advance. You could try disconnecting the vacuum hose & see if it is better. Let us know what fixes it please & Good Luck!

BILL DEMMER

another thought, the obvious one i overlooked, since there wasn't a problem before you connected the "older sun-pro tach", there might be an issue with it, or it's wiring. is it compatible with HEI?


bill

MDchanic

He said he'd disconnected it.

- Eric

BILL DEMMER

yes, i saw that.


bill

olds 307 and 403

Did you remember the ground strap for the coil in the cap? It could be a dying pick up coil or loose connection to it. Usually they just die all together. I would get a different distributor.

XMWZ001

No I did not have it tested, in retrospect I should have. I switched to HEI when I had the motor built. I got sucked into the "1 wire no hassle" bit. I think I have found the culprit was a bad/intermitten connection. I dont know how many times I would check it and have power and then nothing would happen. I went out and bought new parts as back-ups to put in the truck. After spending some good quality time tracing wires and making all new connections. Everything now is loomed and heat shrank and proper. It looks much much better and what do you know, she fired right up and the "miss" at idle is gone. Hooked the tach back up I am not sure if its compatible or how to tell for that matter, but it works. But the short and skinny of it is, everything is working and I havent replaced a thing. I appreciate the suggestions, it was actually a good thing that no one replied for a few days, that gave me time to check the wiring instead of throwing parts at it.

MDchanic

Ha! The simple stuff was the culprit!

Great that you were able to take the time and find it, and, of course, more support for the ironclad rule: ALWAYS solder everything.

I wouldn't worry about the tach - the tach signal from HEI is very standard, so if it works, it works.

- Eric

Ozzie

It's good that you resolved the shortfall. Here's another issue affecting reliability. I'm unsure about your application, but if it's the 1969 Cutlass, this may apply. If you notice that your modules are short lived, and your vehicle has the older style mechanical regulator, change it to a solid state regulator (in the alternator or separate). There is something electrical that mechanical regulators do which some modules don't like. If you like the look of the separate regulator, you can get a solid state one and make it look like the original. And it's still a good policy to carry back-up stuff. The good part about the breakdown is that you get to learn the girlfriend's disposition.

XMWZ001

True on the GF part! I did see a few posts where electrical issues stem from the alternator modules as you mentioned. Do the external solid state regulators wire up the same?

Ozzie

Yes. They are available on the aftermarket. I put one on my 1965 442 years ago, and, so far, all is working well with it and the HEI. Here's the one I used:
http://www.autozone.com/autozone/par...130005_0_11092_
Others may be available. If you want it to look like the original, use the old cover on the new one.

XMWZ001

Very cool, I will look into it. Thanks Ozzie!