What thread are the studs? I want to get new studs in any case. They are all rusted up, and at least one has a missing nut. In daily use, so I've got to do it right the first time.

One of our mechanical lab engineers is excelent with practical solutions. He recons a high quality silicone sealer will do the job until I get a proper gasket. Will see what expensive stuff we have in the lab, and post the name if it is any good. The car is getting to the stage where I've got to accelerate very slowly to maintain sufficient vacuum on the inlet, and I would not have looked at the gasket if it was not for the "running on 3 cylinders" post.

Thanks a million