Fuel filters don't cause vapor lock, but can reduce
the possibility of it since the filter element acts
as a condenser. This is why it should be as close to
the carb as practical.
I don't recall other '74 owners having problems so I
assume the standard fuel line routing, etc., is
basically OK. Your problems imply the underhood
temperature is much more than stock with a 180deg
T'stat.
Are you sure it's vapor lock? Other potential
problems are:
"Percolating", or when the fuel in the float bowl
boils causing pressure wave changes that can make the
float needle to cycle. This may cause the bowl to
overfill allowing excess fuel to be drawn into the
venturi. Very low manifold vacuum at idle (for
whatever reason) can cause power valves to
prematurely open adding excess fuel delivery. Dirt in
the needle seat, power valve or main air bleed(s) can
cause the same effect. A remote possibility would be
that the float has a pinhole leak keeping the needle
from seating.
Last, but not least, the filter may need replacing.
BTW, is the rubber molding that runs along the top of
the firewall still in place? If so, remove it to
improve underhood flow through cooling. I understand
that the early cars have a small front spoiler. If
you have one, then you may want to install the larger
version of later cars.
GM
----- Original Message -----
> I am using a typical can fuel filter to the
carburator. In light of
> this message from Greg, could that be part of my
vapor lock problem.
> The car runs well until it is hot, ~ 1/2 hour, then
it stall and will
> not have even power to start the engine until 15
min. have pasted.
> During the 15 min. wait, it does help if the hood
is open to speed up
> coolong of the motor.
> Ed Eberhardt
> #127
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