fuel coming out of carb overflow when engine hot-RV8

[rac]

Looking for some guidance on a problem I'm having with my RV8 engine stag running on stromburg carbs. Starts and runs fine but once the engine is hot and stopped or ticking over the fuel seems to be boiling in the float chambers-LH seems worse than RH and slowly comes out of the overflow. The float chambers are quite close to the manifold but have managed to make a heat-shield out of aluminium with heat matting to go underneath but still happens, Anyone else come across this and managed to cure it ? I've fitted a switch on the fuel pump circuit so I lower the fuel level before parking up but not ideal in standing traffic. Have an infrared thermometer which read about 56 degs C on the float chambers when it happens-is this high enough to boil the fuel ?

[flying farmer]

Sounds exactly like the knackered float valve problem that Stags suffer from with their Strombergs.

Alternatively your fuel pump is providing too much pressure and this is causing the carbs to flood, which seems to be a common problem with the strombergs.

Neil

[rac]

Thanks Neil thought about fuel pump pressure but it happens when the cars stood with a hot engine-obviously the pump not running then so could be a float valve problem as you say-time to look there methinks

[wilf]

Heat soak into the fuel line possibly, and/or fuel boiling on the carby float chambers (in which case they need insulating some more or rig up a small fan to run for 5 minutes after shutdown).

You could try a solenoid-operated return to the tank, or there are other fixes on here for the problem, a tiny bleed off from the fuel line after the pump back to the tank is but one. Or use heat resistant sleeving to insulate the fuel line from the heat.