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E10 ethanol fuel crappy hot idle

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Bailey28:
The air cleaner valve is disconnected and it is open all of the time. 

Kenth, when engine is warming up and comes off of the choke it is still very smooth at idle.

 This issue starts after the car as been driven then parked and restarted after a hot soak.   It will also happen after high speed driving for a while on open roads.   Coming to a red light it will act up like it wants to stall. 

I'm starting to think I don't have any type of mechanical problem and that the issue may be fuel quality related.  The engine runs perfectly the way it is set up until it gets very hot.   Perhaps the E10 does not want the exhaust crossover under the intake. 

I live in Florida where it is baking hot right now.  This isn't an issue I have during the winter months. 

Bailey28:
Today I raised the fuel pressure to 6.5 psi which seemed to help when idling.


Who knows, maybe with lower fuel pressure and the lower .420 float setting the small amount of fuel in the bowl is boiling quickly causing the unstable idle.   Perhaps with slightly more fuel in the bowl it won't percolate as quickly. 

I would imagine if the fuel in the bowl is percolating then the idle tubes would pick up vapor as well as liquid from the well.  I think this percolated fuel passing by the air bleeds then adds more air to the already percolated hot fuel which is what causes the inconsistent idle. 

Next step might be to raise the float level in the bowl. 

qjetsrule:
Have you considered a thicker base gasket or stainless heat shield?

https://quadrajetparts.com/quadrajet-stainless-steel-heat-shield-thick-p-97.html

Bailey28:
Great idea on the heat shield..

I am using the 1/4" thick Felpro 60482 gasket as well.

I raised the float level to 9/32" which helped stabilize the idle some. 

Today I filled the gas tank full of E0 ethanol free which helped even more. 

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