dual fuel carb gasket

[kitb]

I have a gm 350 and am running dual fuel, edlebrock carb, performer intake manifold and an impco 425. I run propane most the time but every night i turn it back to gas so it will start easier in the morning, and the carb will be full of gas so the seals don't go bad. I have been having a problem with the gasket between the carb and the intake manifold. it starts leaking every 3 weeks and then it has to be replaced. I figure its from the lp drying it out? The gaskets i've been using are the standard Mr Gasket type. are these not good enough? should I use black permatex? or cork? any ideas?
thanks in advance!

[Steptoe]

I have used Dedicated LPG on 350 with performer manifold for over 20yrs, never had a leak...
1/ Do you torque your carb down? If u dont u risk warping the surfaces
2/Check the surfaces are not warped, if they are resurface them on a sheet of glass, about 100 grit wet dry and kerosene...or get them machined

3/ carb manifolds no not require sealant...applying a very thin film of oil to each surface stops the gaskets sticking when dis assembly

4/ One can use something like locktite gasket sealer....again be very careful how much u use, if it spreads inwards up can have problems

the carb will be full of gas so the seals don't go bad.

LPG is inert...it doesnt dry out or attack seals

[Mattelderca]

I'm with Steptoe,
Check to make sure the carb base is not warped, put it on a true flat surface or use a straight edge across it. measure across the bolt holes diagonally. I use a THIN coat of silicone grease on my gaskets, just to keep them from sticking.

[Steptoe]

Check to make sure the carb base is not warped, put it on a true flat surface or use a straight edge across it.

This is the normal method...
Placing on a sheet of glass and a little sand paper, the give a bit of a rub. the less experienced person can then 'see' the high and low spots.