Wall Four help

[gbritnell]

Gentlemen,
I rebuilt a Wall Four engine over the winter for a fellow. I got a chance to start it up last week and the engine started and ran for a short time. The reason for this is because the exhaust/intake manifold is a one piece aluminum casting. To segregate the exhaust from the intake the casting is drilled and reamed through at the the exhaust ports and hollow threaded tubes are screwed through the casting into the head. The remaining area in the plenum is used for the intake. Now I know that I don't have any cooling on the engine at this point but after the short period of running the manifold gets hot to the point that it boils the gas out of the carb (vapor lock). With the design the way that it is I don't see any way of keeping the heat from the carb except to build an adapter with a heat spacer made from Corian or such.
My question is this: does anyone have this completed engine and do you have the same issues as I do?
Thanks,
gbritnell

 

[petertha]

I don't have the engine & not sure if this is helpful. But a common headache on many RC gasoline engines is if heat is able to conduct to the carb/manifold to the extent vapor/boiling issues can disrupt normal fuel atomization making it difficult to tune. If it seems to run for a while & then degrades, this might be a sign. One 'fix' I've seen is some sort of thermal insulation plate between the two. I've seen some nylon or composite material blocks used. Good luck & keep us posted.

 

[TonyM]

In the past I used spacers made from phenolic sheet as heat shield for carbs.

 

[ICEpeter]

Hello George,
ET Westbury's Sealion engine uses a similar exhaust / intake manifold design. I know that Ron Colonna build the Sealion engine quite a while ago and had it running well. Maybe Ron could be of help in this matter with some feed back on his experience with this particular design issue.

Peter J.