"R.D. Waid" wrote:
> I'm still trying to adjust my twin SU setup on my '71 without success, despite
> following the instructions of Haynes, the VTR site, an MG site, and Bentley.
> car idles great with equal hiss at both intakes but begins to miss and die off
> (no power) above idle along with occasional backfires, etc. Timing, points,
> plugs, etc. have all been checked out.
> How many turns of the jet adjusting nut (up or down) are commonly needed with
> properly set up SUs to reach a reasonable mixture setting from the initial
> position (two full turns down from jet flush with the bridge)? I am screwing
> mine out (richer) so many turns that I'm afraid the jet is going to fall off
> the bottom. However, this is the position where I begin to get the slight,
> momentary engine speed increase described in the manuals when the piston is
> lifted 0.8mm. Does this indicate that the jets and or carbs are badly worn,
> need rebuilding? The car still runs lousy at these settings.
Haynes says that after getting the jet centered and the top flush with
the deck, back it off 2 complete turns. That has always worked for me
> Would the carbs need about the same degree of adjustment to reach the correct
> mixture if they were in good condition? The back seems to need a lot more
> enrichment than the front. Also, there seems to be some slop in the
> of the jet of the rear carb when it's level with the bridge.
Theoretically, they should adjust about the same if they are both in
good shape. But using a "Unisyn" adjusting tool, you should be able to
synchronize them. Just make sure that you don't have excessively worn
shafts and/or channels that the shafts ride in. This will let air in
and ruin all your attempts to properly adjust the carbs. If you do
rebuild the carbs. Get the complete kits (the ones with new needles
included). TRF sells them as I'm sure do others. Problem is many sell
kits without the jets.
> What adaptor is needed with a Colortune to work in a Spit engine? Does a
> Colortune come with the right on, or does it need to be ordered? Is this the
> magic tool I need to make this car run properly again?
Sorry, I'm not familiar with Color tune stuff.
> Sorry for the long and wordy post, but this car has been off the road since
> early May with this problem, and I'm slowly losing my mind. It all started
> I bought new air filters!!
Have you checked the filters to see if they are not restricting air
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