Engine not starting when hot and the solution

[mach1000]

Wanted to post what I've discovered and the solution to my problem of hart starting when my 66 Stang engine was hot. The problem pertains to my 66 Stang with a 1970 302 2V in it but could happen to any 2 or 4 barrel carb engine.

Problem: I'd drive my car up to operating temperature to my destination. If the car sat more than 15 to 20 minutes it would be very difficult to start, IE crank over fine but not fire up. If it sat longer than 40 or so and the engine cooled down enough it started right up. But when hot I'd have to crank it and depress the throttle. Then I'd have to rev it up to "clean it out" so it would idle normally again.

In diagnosing the problem I tried adjusting the float in the carb. I also opened the hood and removed the air cleaner once in my garage from a drive running the car up to operating temperature. The hard starting went away when I did this.

Listening to the carb when the engine shut down and sitting hot I could hear it percolating. The carb was getting heat soaked. In doing some additional internet research I found that ethanol fuel boils at a lower temp than regular fuel. I run ethanol fuel in this car with an additive.

Solution: I purchased a composite carburetor spacer. I removed the aluminum one that was on the car and put in Fel-Pro #60529 ($14.99 from autozone). This was used on early 80's Ford products. Much cheaper than $40 + from Summit or Holley but does the same thing.

This insulated the carb enough the hard starting when hot nearly when away.

The spacer is 3/4 inch thick. I may buy one more and double it up for extra insulation but for now it's fine.

 

[MotoArts]

Yep. I've used this one with great success, alternating aluminum plate and gasket heat sink:

http://www.autozone.com/autozone/accessories/Mr-Gasket-1-4-in-thick-carburetor-heat-dissipator-for-Holley-and-AFB-Race-only/_/N-25q8?itemIdentifier=126027_0_0_

 

[Twins]

Wanted to post what I've discovered and the solution to my problem of hart starting when my 66 Stang engine was hot. The problem pertains to my 66 Stang with a 1970 302 2V in it but could happen to any 2 or 4 barrel carb engine.

Problem: I'd drive my car up to operating temperature to my destination. If the car sat more than 15 to 20 minutes it would be very difficult to start, IE crank over fine but not fire up. If it sat longer than 40 or so and the engine cooled down enough it started right up. But when hot I'd have to crank it and depress the throttle. Then I'd have to rev it up to "clean it out" so it would idle normally again.

In diagnosing the problem I tried adjusting the float in the carb. I also opened the hood and removed the air cleaner once in my garage from a drive running the car up to operating temperature. The hard starting went away when I did this.

Listening to the carb when the engine shut down and sitting hot I could hear it percolating. The carb was getting heat soaked. In doing some additional internet research I found that ethanol fuel boils at a lower temp than regular fuel. I run ethanol fuel in this car with an additive.

Solution: I purchased a composite carburetor spacer. I removed the aluminum one that was on the car and put in Fel-Pro #60529 ($14.99 from autozone). This was used on early 80's Ford products. Much cheaper than $40 + from Summit or Holley but does the same thing.

This insulated the carb enough the hard starting when hot nearly when away.

The spacer is 3/4 inch thick. I may buy one more and double it up for extra insulation but for now it's fine.

Those are EXACTLY my symptoms.