At 09:24 AM 6/2/97 -0400, you wrote:
> 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.
Chip,
Did you disconnect the throttle shaft so that each carb will run
independently of each other? Did you disconnect the choke linkage? Both
of these MUST be done to set an SU.
If you think you have work shaft seats, try spraying some WD40 in the air
near the shafts. Does the engine speed up? If so, you might have worn
shaft seats.
>
> 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.)
I have always set the idle in ALL my cars at about 1,000 rpm. At this speed
the gen. is usually putting out enough that the ignition light stays out,
seems to make starting from a stop a lot easier, etc.
I can't believe that if you adjusted the plate on the Uni-syn in that the
red float would come off the stops. I've always been able to adjust the
plate on my Uni-syn to get the float to the top of the tube.
> 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.
I've always set my valves by the book, but a little "loose". You will do
less damage having them a little loose (and noisy) than by setting them
too tight (and quiet).
>
> 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?
Chip, you're right about the long running battle and all the theory about
leaving the thermostat in. However, on my 4/4 I used to take it out in
the summer. Since I've restored it and put in a 160 deg. thermostat, I
haven't been able to keep it cool enough (specially when on the road), not
so much at idle.
Only 3 suggestions here,
1. Is the timming set correctly? This will cause overheating problems.
2. Pull the thermostat and see what happens. If it helps then leave it
out.
3. Try taking an old thermostat and either punch holes in its restrictor
plate or cut the plate out. The outter shell of the thermostat will
help restrict the water flow some. If this helps then leave well
enough alone.
John
John T. Blair WA4OHZ email: jblair@nhr.com
Va. Beach, Va Phone: 495-8229
48 TR1800 48 #4 Midget 65 Morgan 4/4 Series V
75 Bricklin SV1 77 Spitfire
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