Leaking fuel bowl screw gaskets

[dcdoug]

I had some gas seeping past the carb bowl screw gaskets last year and would periodically add 1/4 turn on the screws and it would stop - for a while. I checked it every time I got in the car. (Carb is a 3255-1 with Lemans bowls).

So I’ve removed the carb, replaced the metering block and bowl gaskets (everything looks good and clean inside) and replaced the idle adjustment needle gaskets and the bowl screw gaskets. The previous bowl screw gaskets were white nylon gaskets, the new ones are the Holley black nylon gaskets. Carb bowl screws are torqued to 30 in/lbs. I’ve loosened and re-torqued them a couple times and checked the torque after letting it sit for a while.

I’ve filled both bowls with UV dye (PatrickT’s suggestion) to bench test it for leaking. Both front bowl screws leak (and that’s level, it’d likely be worse as my engine is canted forward). The screw and bowl mating surfaces look good. I’ve tried reversing the gasket on those screws and it still leaks (although it takes overnight to drip, so it’s just v slow seeping).

My options at this point would seem to be:

1) Torque the bolts to 35/40 and see if that fixes it (although I know the target spec is 25-30 in/lbs)
2) Change the bowl screw gaskets to the paper style
3) Change to another brand of nylon gaskets if there are any that are better
3) Try a bit of teflon tape with the nylon gaskets

Other thoughts/suggestions?