I have a MSD-8366 billet distributor on my 502 mag mpi, just bought it in March, well looks like my ign. module is bad as I am not getting any timing advance. I have called around to locate one and the module is part number 84665. My question is since I can't locate one locally, does it have to be an MSD module or are the AcDelco ones the same?

In stock

http://www.summitracing.com/parts/msd-84665

Get an extra one on top of the one you are replacing...they aren't the best for longevity.

what does the module have to do with advance? That is a mechanical advance unit I think, too heavy springs maybe?

I had an MSD mechanical advance distributor get a bit of corrosion on the advance mechanism and it had to be taken apart and cleaned.

Common problem with MSD.

http://www.offshoreonly.com/forums/a...c-dsc00146.jpg And the cure . http://www.amsoil.com/shop/by-produc...?code=AMPSC-EA

It isn't a mechanical advance, it is a 502 mag mpi (forgot to say it was an mpi in original post). The ignition module communicates with the ecu which in turn the ecu communicates with the module to tell the distributor when to fire. So if the module or/pick up, has a magnetic pick up, goes bad it can just lock it self at a set advance. It's all electrical.

I went ahead and ordered one from summit which will be here tomorrow, and I have spoken to MSD considering I just got this distributor March 30th and it only has 35hrs on it they gave me a RA number to send the faulty module in to be replaced with a new one.

Too bad you can't exchange it for a D.U.I. EST. Much better than the MSD unit.

I have seen a few of the same MSD units with bad ignition modules right out of the box. They solder the wires going to the pick up. The could be overheating the module when they solder the terminals. Or, It's from Happy Red China!

I took off all the springs and weights. Lock out my timing at 34 degrees.. No more problems but i'm not sure if you can do this with an efi