What are tricks to Vapor Lock via 1929 Lincoln L ?

Not sure why it has to be an answer specific to the 1929 Lincoln. All cars seem to have the same problem. It's best to get a six-volt Airtex 8011 electric fuel pump. It's the type that can be turned on and off at will. Provides 5.5-8psi of pressure. If you're going to by-pass the mechanical pump, I suggest the Airtex 8089, which only has 2-4psi.

The main thing is to rebuild the mechanical pump first, using the modern diaphragm material.

West, it is a vacuum tank car and the carb is not really designed to hold back anything more than gravity feed pressure (and I have heard far too many tales of Lincoln fires caused from electic pumps).

John,

While not impossible, it is highly unlikely that a vacuum fuel pump can suffer from "vapor lock".

Vapor lock occurs when a pump (push or pull) encounters vapor in lieu of liquid. Pumping ceases.

A gravity feed supply should never vapor lock.

Have they tried to isloate the carb base and fuel lines from engine heat as much as is possible?

Check the lines from the tank to the Stewart for potential hot spots.

Dennis

John,

I was tunnel visioned on vapor lock and forgot to add. Be sure the seats and valves on the Stewart warner lid are

functioning with no leaks.

If I recall correctly the S/W for Lincoln L has an additional vacuum port. Maybe for wipers.

Pull this line and plug it for a test.

Dennis

Cars with vacuum tanks instead of fuel pumps are highly likely to vapour lock especially if the vac tank is near the exhaust manifold. I have had three 1920's Packards each with vac tanks and they are all a PITA in hot weather due to vapour lock. The fuel will actually boil in the vac tank (which can be heard by holding your ear to the tank, or seen by removing the top) so fuel is on the verge of vapour lock before it even reaches the carburettor. It is not a new problem, I have copies of advice by the Packard Co. to their dealers written around early 1930's proposing solutions. Modern highly volatile fuels have increased the problem which is certainly not specific to the Lincoln.

There are many solutions that have been discussed at length on this forum, the best on my cars have been a low pressure Airtex pump bypassing the vac tank feeding directly to the carb and used only when needed - heat shielding the vac tank from any heat particularly the exhaust manifold - adding kerosene to diesel to the fuel - open the hood whenever the car is stopped - avoiding fuel containing ethanol etc. Best of all to drive only in cool weather.

All of the tune up advice and checking everything is good but if the car starts and runs well under all but hot weather conditions then its vapour lock.

When the temperature is up around 100 deg F nothing works in my experience!

Dennis, I assume the vapor lock is in the carb or in the fuel lines - I agree that the vacuum tank is probably not a source of the problem (if I recall the chamber in the tank even has an air space separating it from the outer housing). Keep in mind that this car has an updraft carb and the carb also sits in the valley of the Vee engine.

Car does just fine in 85 degree and cooler weather - problem is all the car events are on 85 degree and warmer days.