400 carbs heating

[Geoff Dowdle]

Dorien ,

I had a similar problem some years ago with my 400. After about 18 years if
trusty service I replaced the 100D2 engine with a 85A engine complete with
reconditioned fuel pump . Cold it would start easily , stop after a drive
for more than 5 minutes it would start but only run for a few hundred
metres then run out of fuel. First thought was defective kit in fuel pump .
Change the diaphragm & valves there was no improvement . I then fitted a
fuel pressure gauge and found it had 3 - 3.5psi cold and under load it
dropped to about one psi .So on closer inspection against another pump found
the operating levers were slightly different . The one being used produced a
shorter stroke and thus less pressure . After bending the first one to
match ,it has been working well ever since at 3.5 psi ,the recommended
pressure.

In Australian summers we get air temps up to 45 deg C and have never heard
of a 6 cylinder Bristol ever having fuel vapourisation problems with either
SU or Solex carbs .

Although my experience is not the same as yours I recommend you test the
fuel pressure from your pump . Its easy to rig up , use a spare fuel bowl
banjo bolt with a barbed fitting & rubber hose to a temporary gauge in the
cockpit . I'd be very surprised if the fuel pressure is not causing the
problem .

Good luck
Geoff

If all else fails fit a 383 and you will quickly learn what fuel
vapourisation is in summer . I had terrible problems with my old 411 S1
until I replaced the cast iron inlet manifold with a alloy one and fibre
spacer under the carb. The cast iron inlet manifold got so hot it burnt the
fibre insulation spacer .