I was having some rough idling this past weekend (not sure why, but assumed
it might have gotten some bad gas) but decided to retune the HIF4's on the
spitfire at my friend's place.
At first the rear SU didn't want to adjust (on the HIF4's the fuel line runs
to the rear carb and the rear float bowl feeds to the front carb float bowl)
no matter how much I adjusted the jet height (it was acting lean even with
the jet all the way dropped). Finally, I went to the electronic fuel pump
and played with it (was running around 4-5lbs. pressure) until I got a nice
steady rhythm (down around 2-3 lbs.) which for some reason seemed to allow
the rear carb to adjust properly. (or maybe it was just coincidence)
I'm also no longer getting any leakage from the over-flow tubes, which has
driven up my mileage.
Also, I'd recently gone from using premium (93 octane Shell) to a regular
(87 octane Amoco/Shell/Texaco) to see if there would be a difference. It
took several fill-ups but eventually I started to get subtle knocking in the
engine. Now I'm back up to 89 octane and it seems to have cleared-up the
problem. (I'm hesitant to use 93 octane in my low compression engine due to
people telling me it will cause carbon build-up.)
Anyhow, I no longer smell like exhaust fumes when I go for a ride. YIPPEE!
Not that anyone cares, but just thought I'd share that little triumph with
everyone.
Terry L. Thompson
'76 Spit (w/'77 low compression engine and HIF4 carbs)
Maryland
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