What model dist# and what model vac adv unit do you have.
The carbs you seem to have are designed for ported vac.
mech timing, vac adv, and mech adv will all fight each other
making it rough to get the idle down and stable.
The dist number is stamped on the body.
The vac adv # is stamped around the neck of the vac unit
right near the vac pipe connection. Give me those numbers
and I may be able to help.
(Also I'm just north of Annapolis if you can stop by with
it.)
:-)
you may want to check out
www.teglerizer.com/mgstuff/advance_curves.htm
and
http://www.teglerizer.com/mgstuff/SUcarbs.htm
Paul Tegler ptegler@cablespeed.com
www.teglerizer.com
----- Original Message -----
From "Eddie Sheffield" <esheffield at prizmail.com>
To: "Spridgets" <spridgets@autox.team.net>
Sent: Saturday, February 10, 2001 7:09 PM
Subject: Help! SU frustrations!
> I'm getting really annoyed with the carbs on my car. It's
a 1971 Midget. I
> can't get the SUs adjusted right for anything now. Valves
have been adjusted
> and timing set. But the thing sounds like a model
airplane. It idles OK, and
> if I sit and rev it that seems pretty good too. But try
driving it and it
> has almost no power and starts bucking and backfiring like
mad, and I have
> to have the choke at least partially out to do that.
>
> A little info for anyone who might help diagnose this: I'm
pretty sure
> everything else is good. When I got the car it had a
strange homemade intake
> bolted to the original intake and a Carter carb. But it
ran, pretty good.
> But I wanted SUs on it, so I took the ones from a 1967
(AUD 136), cleaned
> them up and rebuilt them, including new throttle shafts,
and put those and
> the 1967 intake manifold on the car. Ran OK, but not
great. Had trouble
> getting the idle down. I then discovered the intake had a
crack in it, so I
> took it all off to put the 1971 intake on it. In the
process found that the
> arm on the throttle shaft of the rear carb was on in such
a way that the
> plate couldn't fully close. Fixed that. Both carbs now
seem pretty air-tight
> with the plates closed - I tried blowing through them
while holding the
> plates closed and couldn't do it. Reassembled everything
with the 1971
> intake and 1967 carbs, and thats where I am now. The
distributor is in good
> shape - had it out and cleaned and inspected it carefully.
Put in new
> points, condensor, cap, wires (Magnecor), and plugs (NGK).
Still old coil,
> but it had run well with it before, and in my experience
coils usually work
> or they don't, though they may be intermittent.
>
> I'm guessing the mixture is still off, as it seems like
adjusting the
> mixture doesn't do a lot for it. The carbs are balanced
correctly (according
> to the Carb-Syn) and the idle is right (700 as per
Bentley). One thing that
> seems strange to me, though. With this adjustment the
throttle on the front
> carb is open considerably more than the rear, which is
almost closed.
>
> One other question - the front carb has a small nipple on
it near the base
> where it mounts to the intake, pointing toward the front
of the car. What
> should attach there? Right now it's open. I assume it's a
vacuum port, but I
> really can't feel any vacuum on it, and covering it
doesn't seem to affect
> anything, although I believe it goes straight into the
throat of the carb. I
> have the distributor vacuum advance connected to a port on
the intake.
>
> If there is anyone in the Northern VA area who would be
willing to come by
> and give me a hand, I'd really appreciate it!
>
> Thanks,
>
> Eddie
> 1971 Midget (going to be named Wheezy if it keeps this
up!)
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