This may have already been said, but are you sure your Thermostat is not in upside down?
lol...yeah, I did make sure of that
one thing i just did notice though. I was going thru all my old receipts from when we put the heads on & I saw we purchased the Fel-Pro 1016 head gaskets, not the Fel-Pro 8518 head gaskets. Is there a difference between these two & if there is a difference could that be the problem? taking a stab in the dark here....
Yes there is a difference in the two head gaskets. The #1016 has a wire combustion ring underneath the armor effectively creating a stress riser around the bore. Did you use the Fel-Pro recommended torque procedure or the stock Pontiac procedure? I can pull out my Fel-Pro torque book and see what they recommend if you want. If you have a stock HP engine, you really do not need this gasket. It induces more bend into the head when you bolt it up. Check the torque procedure and confirm it's torqued properly. i.e. more ft/lbs on the bolts. I would definitely use the Fel-Pro recommended procedure in this case.
