Chip Bond and others having high speed power loss problems --
Last year I chased this very problem for three races.
I had one of those ice cube sized Facet pumps and a pressure regulator
on it, regulated to three pounds. The engine cut out part way down the
straights something awful.
Ended up with the interrupter type Facet pump and no regulator and also
no more problems, although pressure at the carbs was 5 psi, higher than
I wanted, using Grose Jets with no problems from them. I purchased that
pump only because it was available at the track. Ran the last three
races with no more problems.
This year we again have the same symptoms. Car loses power on the
straights at Road America and when this happens, EGT goes up, indicating
leaning out.
We did some head work over the winter and I am theorizing that the flow
increase is causing enough more fuel consumption that the pressure and
flow at these high demands is not enough. This theory is based on
measured mpg for a lap and flow / pressure measurements at the carbs. It
may be a wrong theory since Triumphs don't respond to well to
well-thought-out theories.
Since I purchased another identical Facet pump trying to diagnose the
problem, and I had two on my hands, I have installed them in parallel.
My measurements of pressure vs. flow with both setups shows, not
surprisingly, an increase in both. I will see if this fixed it at the
next event. The guys who don't seem to have any of these problems have
big Holley fuel pumps and healthy regulators.
By the way, one lesson learned for sure in all of this is that these
pressure regulators work consistently only when dropping the pressure
significantly - they do not seem to work when set to drop 5 psi to 3
psi, for example.
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