> but when I pulled out the jets to replace the seals I found perished O rings
> and the replacements provided are cork. What is the conventional
> wisdom here.
The originals were cork. Perhaps the current cork replacements have gotten
better, but some years ago I was having to replace them every year on my daily
driver, so I switched to the O-rings from Moss. They seem to last much better.
While you're in there, polish up the outside of the jets where the seals ride on
them. And I would suggest replacing the springs, even though they aren't
included in the rebuild kit.
Another hard-to-find source of idle problems can be worn jets &or needles. Wear
on the needles is hard to see ... inside the jets is practically impossible. If
you can't get the idle lean enough, or the engine seems lean at speed even with
the idle right; try replacing the jets. This turned out to be the reason my
Dad's TR3A overheated on the freeway.
Also check that the pistons move absolutely freely in the domes. You shouldn't
even be able to hear them rub. The domes are soft, and the slightest ding in
the side can screw up the mixture when the piston hits it.
> so I assume that when running if
> the upper seal was as bad the fuel would also feed into the carb
Yup. There's also a brass washer that can leak fuel into the carb throat if
things aren't assembled just right, or the big nut isn't tight.
> Also, I get play at the throttle shaft on both but when I use the old carb
> cleaner trick I get no change. I am assuming that any leak at the shaft is
> not significant enough to bother with.
My experience has been that they don't leak much even badly worn ... I had more
trouble with the butterflies dragging on the bore. Had to blip the throttle to
get them to close.
> From what I can see, and I
> have not had
> the shafts out, the SUs do not have the rubber shaft seal that is used in
> the Z-S.
No, they don't have the seal. It's just brass on brass, but seems to work well,
possibly because the bushings are longer than on the ZS. If you do take them
out, be sure to replace the screws that locate the butterflies with new ones,
and stake (deform) them into place. You really don't want one of those screws
falling into the engine.
Randall
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