Okay, here goes. Some tune up questions for early Plus Four owners.
As I concluded a tune up of my '57 Plus Four yesterday, which was
completely problem free up to then, I found that I couldn't get the
SUs sufficiently rich so that the old "lift the pin" test left the
engine running more or less the same. Keeping in mind that this is a
"new" car to me, I can only guess that a problem that I've seen before
on SU's --- worn throttle valve shafts --- is letting in gobs of air
that can't be compensated for by lowering the jets.
The questions: how much of a raise in the old "pin" is enough to test
for leanness?
At what RPM do Morgan owners tune their carbs? (I found it hard to get
the car to idle much below 900 RPM, and here the little red ball on my
Uni-syn was barely up to the first mark.)
The right-hand jet wouldn't move at all, up or down. Any thoughts,
before a tear down, about what is keeping this jet stationary?
Second major batch of questions. For OLD valve trains, do people
adjust the valves tighter? My Respected Mechanic Friend (previously
cited here) recommends .010, but the factory manual says .013 for
"high speed" cars, but presumably that book was written with brand-new
engines in mind with no wiggle in the valve train.
Third....as I sat there on my milk crate, fiddling with the carbs,
the car proceeded to come to a full rolling boil, including the water
in the catch bottle (this car is used on the track, so I use water and
a catch bottle). Can any of you recommend an electrically powered fan
(hopefully with model #) which will work with this car?
At least I should get things down to a simmer. Br'er Sisson recommends
leaving the thermostat in. I think I had better luck last Summer
leaving it out, although his theory that something needs to keep the
water circulating through the radiator at a deliberate pace is worth
thinking about. Any (other) thoughts?
Chip Brown (ebrown@ms.com)
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