FUEL
RETURN VALVE (OPTION) #161-B2
The
fuel return valve found on 68-70 cars allows the
carburetors to draw what fuel they need, with the rest
of the flow returning to the tank. This keeps the fuel
cooler which helps prevent vapor lock from high
underhood temperatures. Original Valve on the left is
currently unavailable. The valve on the right is off
of a Japanese version SU carb set and is currently
available and about 1/3 the cost of the original. The
fittings on it however are vertical rather than
horizontal. It mounts to float bowl fine, but you'll
have to get some universal 90 degree adapters to hook
your fuel lines to this valve. Using your fuel line
without some hard fittings to make the angle changes
will put stress on the tubing and probably cause it to
fracture.
Typically
it is necessary to either mount the valve on its
bracket backwards, or in some cases people have used
this by mounting the fload lid sideways. You want the
valve to not hit or interfere with anything else on or
near the carburetor.
Original
Valves originally did not come with brace and nut
locking ring, which allowed the valve to loosen up on
float bowl. Also, if the fuel lines were not replaced
frequently enough, they would harden. Normal engine
vibration would not be absorbed by the flexibility of
the fuel line, and the outbound fuel fitting would
fracture, causing leaks. Always use high quality fuel
line and replace it when it starts to harden to reduce
your chances of a gasoline leak.
GETTING
RID OF HEAT..If
necessary for further heat reduction, you can also
wrap your fuel lines with the type of insulation found
on later Z cars (and lots of others)There are some
special coatings available for headers and manifolds
which reduce underhood temperatures. Heat is hard on
everything, and your engine's performance is better
with colder air.