Vapor Lock? How to Prevent?

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RDSChicago

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Today in Denver it was very hot, around 80-85 degrees, and I drove around 90 miles, most on the highway going around 75 mph. My 2800cs has dual Weber’s. The car ran fine all day. When I was a half mile from home, the car sputtered and bucked, and then stalled. It wouldn’t start. I opened the hood and waited around 10 minutes. The car then started and I made it home. Sounds like a classic case of vapor lock? What are the fixes to prevent this from happening again? I have no mechanical skills at all!

Here’s what Google told me:

How to address the problem
  1. Add Heat Spacers: Ensure you have thick phenolic or plastic insulating spacers (about 1/4" thick) installed between the bottom of the Weber carburetors and the intake manifold. These act as a thermal barrier to stop the engine block's heat from transferring directly into the carburetor bowls.
  2. Route and Insulate Fuel Lines: Make sure your fuel lines are routed as far away from the cylinder head and exhaust manifold as possible. You can wrap the lines in silver thermal insulation sleeves.
  3. Check Your Fuel Pump: Weber carburetors need a constant, steady supply of cool fuel. If you are still running the mechanical pump on the front of the cylinder head, it absorbs massive engine heat. Upgrading to a low-pressure electric fuel pump (like a Carter P4070 or a Pierburg pump regulated to 3 PSI) mounted near the rear fuel tank forces liquid fuel forward under constant pressure, which greatly reduces the chance of the fuel boiling in the lines.
Sound line good advice? Any YouTube videos out there to show me how to take these remedial actions? Any other advice?

Thanks.
 

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RDSChicago said:
Today in Denver it was very hot, around 80-85 degrees, and I drove around 90 miles, most on the highway going around 75 mph. My 2800cs has dual Weber’s. The car ran fine all day. When I was a half mile from home, the car sputtered and bucked, and then stalled. It wouldn’t start. I opened the hood and waited around 10 minutes. The car then started and I made it home. Sounds like a classic case of vapor lock? What are the fixes to prevent this from happening again? I have no mechanical skills at all!

Here’s what Google told me:

How to address the problem
  1. Add Heat Spacers: Ensure you have thick phenolic or plastic insulating spacers (about 1/4" thick) installed between the bottom of the Weber carburetors and the intake manifold. These act as a thermal barrier to stop the engine block's heat from transferring directly into the carburetor bowls.
  2. Route and Insulate Fuel Lines: Make sure your fuel lines are routed as far away from the cylinder head and exhaust manifold as possible. You can wrap the lines in silver thermal insulation sleeves.
  3. Check Your Fuel Pump: Weber carburetors need a constant, steady supply of cool fuel. If you are still running the mechanical pump on the front of the cylinder head, it absorbs massive engine heat. Upgrading to a low-pressure electric fuel pump (like a Carter P4070 or a Pierburg pump regulated to 3 PSI) mounted near the rear fuel tank forces liquid fuel forward under constant pressure, which greatly reduces the chance of the fuel boiling in the lines.
Sound line good advice? Any YouTube videos out there to show me how to take these remedial actions? Any other advice?

Thanks.
Click to expand...
Your Webers probably already have the spacers. They should anyway.

Insulating the fuel line, especially if your fuel line is metal, is a good idea.

A weak fuel pump is a likely culprit.

I have the very same car with a simple little electric pump and no issues.
 
I have an electric fuel pump on my firewall that I use to fill the carburetors after leaving my Coupe sitting for a week or more. The few times I've had a problem with vapor lock on a very hot day, as soon as the engine starts misfiring, I turn on the electric pump, and the engine begins to run smooth again. That is all I have ever needed to overcome vapor lock.
 
Electric fuel pumps do help. However they do push better than pull.
Several have put them near the fuel tank.
Dick Steinkamp

Thread 'Electric fuel pump to prime carbs'

It seems that most of us with 38/38 or 32/36 Webers experience dry carb float bowls if our car sits for a relatively short period of time (>4 days?). I've put up with this for a year or two, but it's annoying and tough on the starter and battery and time to address the problem.

I've owned many collector cars with carburetors. Some had the same problem, some didn't. I could never figure out a common thread for those that did. New, rebuilt, old...it didn't seem to matter. Some did, some didn't. I could never pin down where the fuel was going. It couldn't be backing out of the carb up...
 
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