I parked it in the garage, running fine. Next day, it won't run. When I turn the ignition to the 'start' position, it fires up. But when I let the ignition key go to the 'run' position, it dies. I can even rev the engine a time or two with the key in the 'start' position, but it dies immediately when I let it go to 'run'. I have checked the fuel pump, and the carb is getting PLENTY of gas. I have replaced the ignition switch, still no joy. I'm pretty much at the end of my (very) limited experience, so if one of my fellow Chevelle owners can give me a hand with this, I'd certainly appreciate it.

Let's see...battery is new and full of juice, it has a new Mallory HEI, new plugs and wires, all fuses appear to be good, and a new ignition switch. Any ideas?

Measure the voltage on the HEI input while the key is in the RUN position. It sounds like you are losing that when you let go of the key.

I did that and I am getting less than 2 volts, where it should be a minimum of 5-7, correct? This is really driving me crazy! Suppose that is the problem, then what should I do? Appreciate the assist on this.

John, I am having the same problem srubydo described in his post on 16 April. Did he figure that one out?

Mallory HEIs work off the resistor wire?? Is that what you are using? Thought they needed a full 12 volts.

Let's see...battery is new and full of juice, it has a new Mallory HEI, new plugs and wires, all fuses appear to be good, and a new ignition switch. Any ideas?
New Mallory HEI? What kind? Mallory coil in cap HEI, similar to stock GM HEI? Like John said that should be running a full 12v. The resistive wire should have been replaced with a regular wire.

It's the Mallory 85 Series HEI, #8548201C. Now bear in mind that I am a complete newbie at this stuff, so speak slowly when explaining things please.....

Do the instructions for that Mallory ask for a 12 volt line? I think they do.
Where are you getting that 12 volts from?

This may be of help, originally posted by Birmac,
"I've been using an HEI w/ a Mallory module & Accel coil, for years ... in my 70' Elky. Recently, this vehicle quit running, caused by loss of 12v power to distributor. I was a little surprised when I discovered the source of the problem .... And, this is what I found. ----- I was using the original harness wire (white,cloth fabric covered) for 12v. In the harness, behind the master cylinder, this wire had burnt through, but not it's covering. This was not near a connection or splice, which could have caused high resistence. Ran a new larger wire from fuse box to distributor .... and problem solved. I first thought the problem to be at the wiring harness bulkhead connection. I don't know if this is a common "problem", but hopefully this can help someone else."

You may want to read this entire post, Birmac Jan 27th, JM help him out.

Fred.

John I looked up that Mallory just a few days ago. It is a standard type HEI distributor, coil in cap. It does need a full 12v to the coil. Sounds like he may have burned up his resistive wire, assuming he's still using it.

Yeah, sounds like he's using the resistor wire.

OK, the wire coming off the coil is a thick, orange wire, but that is not indicative of anything as I discovered that this is merely the way someone rigged it up. They took two other wires, one yellow and the other which looks like it may have been covered by some sort of braided material at one point, and wired them together with the small orange wire, which has the connector on the end for the coil. This was very poorly done by whomever did it, and is very likely the source of the problem. What I need to know now is 1) what part do I need to fix this correctly, and 2) how do I go about doing that? I have taken pics for your reference, but don't have permission to insert them I guess. Either that or I just don't know how. Appreciate your help on this guys.

You can insert pictures, just upload them here
http://www.imageshack.us/ after you upload them (click "host it") you will see a line for message boards "hot link for forums" to highlight and copy, then past into your post.

or just use the " url of image tags in your post

Not that familiar with Mallory wire colors. This link may help. As Hank said the Mallory needs a full 12 volts. Get rid of the cloth covered wire that's attached to the yellow wire. Run a new wire from the fuse block IGN terminal and use that instead of the cloth covered wire.
http://go.mrgasket.com/InstructionSheetsList.aspx?BrandID=6

Pic might help but sounds like you just need to replace the mess. The yellow wire should run down to R terminal on starter, you no longer need it with an HEI. The wire with braided insulation is the resistive wire it's no longer needed either. You need to trace the resistive wire down to the fuse block. You can remove it with a small flat blade screwdriver. Then go to the parts store and get a new terminal to plug into the fuse block and a new one to plug into the distributor cap, they should have both. Run a new 12 gauge wire from the fuse block to the cap and you should be good to go.

EDIT: See John must have responded while I was typing.

OK, I'll get that wire replaced. As for the one coming off the starter, you say I don't need a wire going from starter to distributor? Or did I misunderstand that?

Also, I have discovered a thin, blue wire with a small rubber 'boot' looking thing on the end. It was just laid over behind the master cylinder. Any idea what in the world that might go to?

I parked it in the garage, running fine. Next day, it won't run. When I turn the ignition to the 'start' position, it fires up. But when I let the ignition key go to the 'run' position, it dies. I can even rev the engine a time or two with the key in the 'start' position, but it dies immediately when I let it go to 'run'. I have checked the fuel pump, and the carb is getting PLENTY of gas. I have replaced the ignition switch, still no joy. I'm pretty much at the end of my (very) limited experience, so if one of my fellow Chevelle owners can give me a hand with this, I'd certainly appreciate it.

Let's see...battery is new and full of juice, it has a new Mallory HEI, new plugs and wires, all fuses appear to be good, and a new ignition switch. Any ideas?
I'm almost ashamed to tell this one, but I had that happen last summer after installing a ZZ502. Of course the 502 is not machined for a mechanical pump, so I had to go with an electric. Rather than run the lead from the pump to the ignition, I ran it to the solenoid on the starter. When I'd hit the ignition, she'd fire until the solenoid released.....then die.

I'm almost ashamed to tell this story........but i installed a ZZ502 in mine last summer. Of course, the 502 is not machined for a mechanical pump, so I mounted the electric and ran the lead to the solenoid, rather than to the ignition. She'd run until the solenoid released, then quit.