Bill:
Here is a try.
>What is a Gulp Valve and what does it do?
Used from 70ish onwards. When the carb. butterflies close there
is a moment when there is raw fuel still spewing into the intake
manifold. With closed butterflies the manifold vaccuum goes high
opening the gulp valve. Air from the air pump then enters the intake,
mixes with the raw fuel and a nice combustable mixture goes into the
engine. No more cloud of hydrocarbons upon backing off the throttle.
An operating gulp valve will not affect engine performance.
Problems. Drivability, back off throttle, engine tends to
continue to run. Less engine braking. If the gulp valve fails open
(unusual) or leaks the mixture will be diluted. Tuning becomes a major
problem. Requires operating air pump to be effective.
>What is an E.G.R. valve and what does it do?
Similar to the Gulp valve, the EGR valve opens on deceleration
and dilutes the fuel rich intake tract with exhaust gas. Added benefit
is that the exhaust gas at this time is fuel rich too, so some of the
hydrocarbon rich exhaust is recirculated. The exhaust gas also heats
the intake charge which is of benefit under some conditions. An
operating EGR valve will not cause any real reduction in performance.
Problems. Again if the valve fails open or leaks the mixture
will be diluted. Requires the silly log type manifold to operate.
>Same for Anti-run-on valve?
A very useful device which is activated when the ignition is
switched off. The circuit runs through an oil pressure switch which is
normally open. Oil pressure keeps the switch closed until the pressure
drops following engine shutdown. The valve allows intake vacuum to
reach the carb. float bowl cavity. With the float bowl under vaccuum no
fuel gets sucked into the engine. No fuel, no run on, The engine shuts
down nicely without trying to claw it's way out of the engine
compartment.
No problems. I have seen this device used to cure run-on caused
by high compression pistons and incorrect idle advance on race cars.
>How important is the Fuel cut-off valve and what does it do?
The silver cut off valve was located behind the brake/clutch
assembly. It was a mechanical flow valve that would shut fuel flow off
if the car went upside down. The valves tended to leak and most have
been removed. The late cars also had an electrical shut off switch
under the dash that shuts power off to the pump. The electrical switch
is nice insurance. MGBs' though do not tend to burn on impact.
> someone local suggested that I remove all
the "emissions crap". What are the mechanical consequences (let alone
legal) of doing that?
Kept in good tune, a 62-67 MGB will perform well and pollute
less than a poorly maintained later car with defective controls. It is
important to understand completely what each part in the system does
before removing it. The engine systems were designed to work together.
The most important thing is to make sure that the engine crank case
breathing is not plugged. This is a common error leading to excessive
oil burning and leakage. Check the legality before doing any
modifications. Check here if you have any doubts of how a system works.
Hope this helps.
Kelvin.
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