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Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
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So much attention seems to be devoted to issues of vapor lock/heat soaking, I thought I would post an absolutely foolproof--if a bit radical-- solution to this pervasive problem I cam up with several years back.
The car in question is NOT my 1954 100 Le Mans but rather my first race car--a 1622 MGA-powered Elva Courier equipped with two HS6 SU's. On hot days it was often impossible to get the car to restart once the engine got hot--which often happens when, for example, there were delays on the starting grid and it became necessary to shut down due to threatened overheating OR during restarts after an all-in black flag etc. In such situations when the engine was "heat soaked" no amount of cranking would work until the engine cooled down and on a few occasions I actually missed getting off the grid--quite frustrating to sit there watching the race proceed without me.
The solution I came up with was to provide a simple, positive way of getting relatively cool air into the combustion chamber: The intake manifold had a balance tube in which there was a threaded. plugged port. I inserted a brass 90 degree ell into the port and ran a fuel-proof hose (1/2" ID) back through the firewall to a brass two-way ball valve with a lever handle which I mounted through the dashboard near the steering wheel so that the handle was easily accessed simply by reaching under the dash.
When it came time to start/restart a hot engine I would crack the valve open with one hand and push the start button with the other. Invariably, despite high ambient or engine temps the car would fire off immediately and I would close the valve immediately as it almost seemed like the car had received a straight injection of starting ether! My ultimate intention was to replace the manual valve with a spring-loaded version that would immediately close when released but I sold the car before doing this.
I'll admit this might be an extreme solution but if one lives in a very hot high temp/humidity climate and/or is continually plagued by what we call vapor lock or heat soaking (luckily not a problem from which my 100 suffers) it is worth exploring.
The car in question is NOT my 1954 100 Le Mans but rather my first race car--a 1622 MGA-powered Elva Courier equipped with two HS6 SU's. On hot days it was often impossible to get the car to restart once the engine got hot--which often happens when, for example, there were delays on the starting grid and it became necessary to shut down due to threatened overheating OR during restarts after an all-in black flag etc. In such situations when the engine was "heat soaked" no amount of cranking would work until the engine cooled down and on a few occasions I actually missed getting off the grid--quite frustrating to sit there watching the race proceed without me.
The solution I came up with was to provide a simple, positive way of getting relatively cool air into the combustion chamber: The intake manifold had a balance tube in which there was a threaded. plugged port. I inserted a brass 90 degree ell into the port and ran a fuel-proof hose (1/2" ID) back through the firewall to a brass two-way ball valve with a lever handle which I mounted through the dashboard near the steering wheel so that the handle was easily accessed simply by reaching under the dash.
When it came time to start/restart a hot engine I would crack the valve open with one hand and push the start button with the other. Invariably, despite high ambient or engine temps the car would fire off immediately and I would close the valve immediately as it almost seemed like the car had received a straight injection of starting ether! My ultimate intention was to replace the manual valve with a spring-loaded version that would immediately close when released but I sold the car before doing this.
I'll admit this might be an extreme solution but if one lives in a very hot high temp/humidity climate and/or is continually plagued by what we call vapor lock or heat soaking (luckily not a problem from which my 100 suffers) it is worth exploring.
