I am currently replacing the head gaskets on my 99 3100 sfi cutlass supreme and now need help identifying which valve is which (exhaust and intake) I have the intake manifolds put back on and now cannot tell which valve is which :-( The only thing I can find in any haynes or chilton manual tells me that the intake pushrods are longer and the exhaust rods are shorter...But not which valve is which, I need help, please!
-Brad

no one knows?

If you know whether your car is a J or an M VIN, your best bet might be to go here:

http://www.partsamerica.com/Default.aspx

Click on "Replacement Auto Parts" on the left column and then pick out your year/model.

For the M model, it shows the intake valve being larger at 1.718" diameter. The Exhaust valve is smaller at 1.425 " diameter.

For the J model it only shows the intake diameter at 1.76" diameter. It doesn't show the exhaust diameter.


Hope this helps!