'78 Trans Am HEI
 

I have a '78 Trans Am 400cid HEI Distributor I'm going to be rebuilding. What are the things I usually need to replace on an HEI?

Thanks.

HEI
 

On mine, i replaced the usual: rotor, cap, coil, wires, plugs...
ran great for a month, then the HEI module died.
It took a while to figure out, there is a diagnosis link on this forum.

So, I would go ahead and replace the HEI module with the proviso
that you get an AC/Delco module. The repro ones have terrible failure rates.

very good reading here.......http://www.chevelles.com/techref/ftecref5.html

Thanks guys! Very helpful.:)

In that link to the HEI info, notice that you need to be sure to put the white heat sink compound under the module when installing one. A new module comes with a packet of it. But, if you are re-using a module, you'll need to get more heat sink compound. I had a hard time finding it at a parts store, but Radio Shack sells it in a tube, and you get more for your money.
The module gets hot and the heat needs to be transfered to the body of the HEI, so that's why you need the heat sink compound. If you don't have it or use something different, the module will go bad.
There's some bad info out there that says that dialectric grease can be used, but it's wrong.

Take the distributor apart and check for slop; also clean all the carbon & crap off the shaft; it can slow down advance. Get some different springs for quicker advance -

The most important part to replace, if you take all the way apart, is the magnetic pickup. It is proven to fail, one of the two small wires will break, caused by the vacuum advance moving it. All the other parts can be replaced w/ the distributor in the car/engine.

When I take one apart, I check to make sure that there is no wear in the bushings. I polish the shaft and bushings to smooth them up. I gease both bushings. I slide the shaft into the top bushing, and before I engage it into the botttom bushing, I squirt a little motor oil into the housing. Sounds like overkill but the shaft is only lubed by oil vapor in normal operation.