Where To Source Pre-Cups??

[mikeyg1975]

Does anyone know where you can buy Pre-Cups from, I have looked, even punched in a Google search for pre-cups, came up with a bunch of stuff, but no conclusion on where to source them from, any help would be greatly appreciated!!

[Robyn]

GM used to sell them through the parts dept.

Stay away from the aftermarket stuff that comes by boat if you can.

Be sure the counterbore in the head is spotless with ZERO crap in the register area.

The cups do no have to be a press fit BUTTTTTT, must be flush to .002 or so above the head surface.

All cups must match, very important NOT to run a mixed bag.

The standard one today has a <> diamond on it.

There have been many incarnations over the years.

They vary in port size and internal volume.

The turbo engines use the larger port size.

The was and early 6.5 set that had a T on them, and they are ok too.

If the cups tend to want to fall out easy, just lightly peen the head a little bit with the cups in a couple spots on opposite sides to retain them while you install the heads.

A small round nosed punch will do the trick.

No need to get crazy, just a tiny "nerf" on two sides to keep the cup in the hole is all.

Used sets may be found on ebay cheap, just be sure they match.

Good luck

[mikeyg1975]

Robyn, As always you're a wealth of knowledge, appreciate the good info!! I found genuine GM cups at PTCpower.com, and they have all variations as they service the military stuff, so I will order the diamond pre-cups...I hear you on the clean part, you can never be too clean!!

[Robyn]

A word to the wise.

NEVER EVER machine heads with the cups in.

The cups are best if the stick up .001-.002"

This assures a good seal against the head gasket.

Good luck