Buick 300 4.9L Gasketing Questions

66Ruby

Member
I have a 1966 Buick 300 that I am reassembling.  I am questioning the recommended sealing procedure for the intake manifold, thermostat housing, and carb gaskets.  I have always been a fan of dry gaskets, but there seems to be much discussion out there recommending otherwise.  The gaskets are Fel Pro and came with no manufacturer recommendation.  My plan was to apply a thin film of Permatex Ultra Gray to both sides of the intake manifold gasket and the end seals.  Same with the thermostat housing but using blue RTV on both sides of the gasket.  The carb gasket I'm not sure as RTV is not good with gasoline.  Any advice from previous experience would be appreciated.  Thanks!
 
More than one solution will be satisfactory. I have never used dry gaskets.

I am sure the Permatex Ultra Gray will do the job on the intake and the thermostat housing. It should be just fine on your carb gasket too, it won't be subjected to any significant gas.

Myself, I would probably choose a less aggressive sealant on the intake to head, Permatex High Tack Gasket Sealant 80062 or Permatex Aviation Form-A-Gasket No. 3. The Ultra Gray would still be the choice on the ends. One of the sealants would work for the thermostat housing (Be sure that the housing surface is flat, many are warped.) although I treat mine the same way as I would treat the carb gasket. I would simply wipe both sides with grease and install. If you ever take the carb. back off, the gasket will not stick.

Items like valve covers which frequently come back off, I use a sealant between the cover and the gasket, and grease between the gasket and the head.
 
Thanks Bob. So sealer between the gasket and heads, but would you use anything between the gasket face and the intake manifold surface? When I removed the intake, the old gasket was stuck to the heads pretty good (sealer) but it came free from the intake without much issue. I'm reluctant not to use some RTV around the water jackets, but I don't think it had any originally???
 
I think you will find that "originally" virtually no gaskets were installed at the factory with sealers. Sealers are often used to compensate for some potential deterioration in surfaces. RTV (or any silicons) sealers were not around when your 300 was made, so when you find some, it has been apart. If you are more comfortable using RTV on the intake side, then do so, there is absolutely no reason not to and it may avoid a leak from a flaw you don't notice.
 
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