I have a 66 with a Blueprint 383/430. I am using a 69 Z/28 intake and an AED 650 mechanical carb ( two accelerator pumps). I have been having A hot start issue forever. The engine would start fine after sitting up to 5 minutes. After 5 minutes the engine would be flooded. If it sat overnight it was fine. I was lurking on the C3 forum and found where Lars addressed this issue. I emailed him and he sent me his paper on how to resolve it. I bought the Holley plate and installed it with the .330 spacer supplied in the kit. It fixed the issue but I couldn’t close my hood. I replaced the thick .330 thick spacer with 3 Mr. Gasket gaskets that are .063 thick and I can close my hood. The hot start issues are gone. I have checked the intake, plate and carb temps and the plate really reduced the temp being transferred to the bottom of the carb. The difference is 40-50 degrees.

lars explains that the intake is so close to the accelerator pump, that fuel is forced out of the carb and into the intake when the engine is turned off. So when you go to start the engine after sitting 30 minutes, it’s flooded. My carb has two accelerator pumps so my issue was much worst then the oem carb. Btw, the engine really likes this cooler carb and runs better.

My friend GordonR had the same issue with a QF carb. He made a plate using mine as a template and his hot start issue was resolved.

Here is a picture with the air cleaner removed.

 

Great post and I'm sure it will be very timely, also great information from Lars with the explanation of what's happening to the carburetor during heat soak.

The corvette engine compartment is very restrictive when it comes to heat, just releasing the hood latch helps some.

 

I have an FE Cobra replica with twin Holleys and it was percolating the fuel out of the accelerator pump thru the shooters into the bores. It has an original low rise 427 intake and the accelerator pump housings are pretty close to the manifold and getting a lot of heat on heat soak after shut-down. I used the Mr. Gasket insulator kits which helped a lot with the problem. I also had some Be Cool closed cell, foil backed insulation left over and I cut small sections out to tack on to the bottom of the pump housings with a dab of dum-dum to additionally reflect radiant heat which helped more. I have a feeling these accelerator pumps do this a lot more than realized with Holleys. Congratulations on fixing yours.

 

You have to be careful about tightening down a Holley carburetor with all those stacked up soft gaskets. It's easy to break an ear off the base plate on them.

Glad you fixed your problem. Those heat shields have been on the market since the '60's. Way before E 10 FWIW. Carbs bubbled back then, too.

 

Yes - fortunately I tend to under-tighten most small bolts and screws. Change a fuel bowl gasket - I have to go back and re-snug them 3 or 4 times before theY stop relaxing and seepIng fuel after a drive. Same with valve covers, oil pans and transmission pans. It’s a behavioral pattern.