HEI conversion problems

[jpsage]

Hi,
Awhile back I installed an stock gm hei in my 72 c20. I bought a rebuilt gm hei distributer and associated parts from my local NAPA and went for it. After about 2500 miles, it wouldn't start because of no spark. I took the cap off and fiddled with the rotor, put it back together and it started right up. Then I blew a timing chain and ended up putting a new crate engine in. Now the hei is still acting up. The truck won't start and I will tear the cap off, fiddle and put it back together and it will run again. I have replaced the coil, cap and rotor and it still happens. I thought maybe the current demands on my ignition switch was too much so I installed a relay that switches battery power directly to the distributor when the key is turned on.

Finally after it sat for a week and wouldn't start I left for the autoparts store figuring that I would by what ever performance system that the had in stock. My local Parts + store had a performance aluminum CSI hei that looks exactly like the gm but brand new and at a reasonable price. I took it home and installed it. The truck fired up but it is not running all that well. i notice that the timing light seems to skip some beats. Tomorrow morning I am going to hot wire it directly from the battery and see if that makes any difference.

Anyone else have similar experiences with HEI? This really shouldn't be that difficult but I sure am having trouble with it. Thank for any ideas.
john.

[zeeklu]

HEI takes a full 12 volts.The wire going to the old points is a resistor wire and only delivers around 8 volts.Thats the only thing I could think of besides loose connections somewhere. Chris

[truckdude239]

run a new wire from the fuse box make sure it is switched so that the truck will cut off when you cut the key off

[mtndewmaniac66]

Originally Posted by truckdude239

run a new wire from the fuse box make sure it is switched so that the truck will cut off when you cut the key off

Ditto. I ran a 12ga wire directly from a switched lead to my dist. Never had any troubles, plus the thicker wire (with out going too heavy) will carry the electrical current better, thus improving coil performance, improving spark.

BTW, this is an often overlooked item when converting to HEI, a common mistake. No worries.

[Longhorn Man]

it kinda sounds like he already did that, and then the relay set up is far better than the fues box or splicing into the pink wire.

[jpsage]

Well I finally found the problem. I went to the parts store to buy an after market distributor and found a brand new unit that looked exactly like the gm, made in Australia and packaged in a plain brown box for right at $100.00 (during the original upgrade the parts together with a rebuilt dist from NAPA cost me well over 200). I figured what the hell, I went for it, installed it and no more problems. Once on the bench, I did a close inspection on the old unit and found that the connector going to the magnetic switch was badly cracked on the bottom. Probably was cracked from the rebuilder and just got worse over the past two years.

But I found the problem and the truck now seems reliable. Thanks for the ideas. Now to get the beast painted with the original green paint! It would be nice to have an extended cab diesel truck to motor around in but when I go out and see that proud old Chevy sitting in my drive! What a great looking truck gm made!!!!!!

Great motoring to all....