When I got my sled ('73B) the engine was essentially stock, altho it
had been worked on (0.040 overbore). The idle would not go below 1500
and the engine would not go above 4000. It had a flat spot nearly
everywhere. I tried a number of things to improve performance
(with the carbs on the car) but no go. I yanked the HIFs and replaced
with a DGV, Pierce manifold. The engine was much more tractable--idle
correct, much better top end, but a modest loss in torque in the lower-midband.
I got the distinct impression that it was running "smoother" at all speeds.
I believe the effect was not imaginary or subtle, because it was
commented on by my SO. I do not know the details of the jets
installed, the unit was bought from Northwest Import Parts and he set
the carb up. The float was set 1 mm down from factory spec (as
specified by Pierce). According to the colortune, all mixtures are
spot on.
When I got around to examining the entrails of the HIF's, there was
nothing grotesquely out of order. The throttle shafts were tight (and
seals were intact), floats were set properly and the poppet valves
were soldered shut. I cannot speculate on why they were not working
properly. I have since rebuilt them and intend to slap them back on
some time this summer for direct comparison now that I have had
experience with the Weber. It would seem that the SU's would have
overall a bit more performance since their aggregate throat area can
breathe a bit easier than the progressive Weber, but the Weber is very
well-behaved.
A. B. Bonds
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