Dan,
You said that you had soldered the butterfly valves and that rang a bell in
the back of my mind. Just went back to Peter Burgess' book and reread what
he said about the HIF and the butterfly valve. Apparently the spring loaded
hole in the butterfly valve is there to let more air in when you let off the
throttle to give better emissions to meet the increased standards. The
implications of soldering the hole up and increasing the air flow is that it
should lean out your mixture, which you in turn probably richened up to make
the car run better. Thus when you let off the gas and cause an large
increase in vacuum, too much gas may be sucked into the manifold flooding
out the engine. Peter also recommended that you change the needles in the
carbs to adjust for the leaner mixture and gave a couple of possibilities.
Perhaps that is what is happening to your 72 MG.
Dave 72 B
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