Technical 1955 Ford Y Block will not start when hot

I have a 1955 Ford Thunderbird Y-block that starts well when cold and runs fine. It will not restart when hot after being shut down for 15+ minutes.
Read most of the posts;
1. Turns over freely, proper battery and right sized cables.
2. Has a phenolic spacer.
3. Added inline 2 psi electric fuel pump
4. Carb has been rebuilt with ethanol gaskets and tested/ run on a Y block
5. Fuel lines and regular fuel pump replaced with ethanol components.
6. New coil
7. Added Pertonix electronic ignition.

What am I missing? It needs to sit 4-5 hours after being shut off hot. I am getting to be to good a friend of the tow truck driver.

 

Have you checked for spark when it will not start? Gary

 

Yes solid blue spark.

 

How about a hot compression test, or a hot cranking manifold vacuum test?

 

Does the starter motor spin the motor over at the same speed as when it's a cold start ?

 

Do a compression or a cylinder leak down test.

 

sounds like it could be vapor lock. check for components too close to exhaust system etc. also the electric pump should be closer to the tank as to push the fuel rather than pull it.
hope this helps
jim

 

2x^ carguy699, unless your valve lash is too tight and you are loosing compression when hot...???

 

Insulated the fuel lines and nothing is close to the exhaust on the furl train.

Spins over at the same speed hot or cold.

I will try hot compression test today.

 

a 12V conversion will fix it.

 

Well I took the car to a local mechanic who works on older cars. Ran a vacuum test and the vacuum decreased at idle when it got warm. Brake booster was leaking. Replaced the booster starts and idles smoother.

Never thought to look for a vacuum leak?