Weber fuel bowl boils over?

[Frostie]

My project car (74 –911) has a 3.0 with webers. I’m in the midst of putting her back together and my local P mechanic has informed me of one of the inherit problems he has seen with the webers is when you shut the car off, heat from the engine travels up the intake manifold and into the carbs where it boils the fuel out of the bowls. The result is when you fire your girl up again she is flooded and there is a potential of a fire hazard. I have never heard of this problem before. Has anyone had any experience with this?

[jtf914]

You can use insulator blocks which reside between the heads and the intake manifold which help to reduce heat transfer to the carbs, and there is also a vent kit which allows the release of any fumes from boiled fuel. Both are available from PMO

I'm pretty sure the insulators were standard equipment on the 914-6 due to the reduced air flow/higher temps in the engine compartment. Haven't heard too many 911 owners complain about their webers percolating.

-Justin

[TimT]

where it boils the fuel out of the bowls

the fuel in the bowls is gone makes the car hard to start after the fuel has evaporated from the carbs. The car wont be flooded though. Like Justin mentioned you can get insulators from PMO, these help with the fuel percolationg, and also add about 3/8-1/2" to you manifold heigh which is a good thing.