Question about vintage dual sidedraft carberettors:

Apr 20, 2006 2 Replies
E

Is anyone an expert on the side draft SU and Stromberg, jet and needles?



Are jets essentially the same; only the needles (as marked) different? Do these carburetors, fitted with various needle applications, essentially each have common jets?



If, as long as needles match, is the only difference in jets going to be any wearing, out? (Say, one carbo with a brand new jet, the other, with used jet of unknown age, but both rebuilt with new needles?



Or, it now looks like I might have got two, NOS (SU) rebuild kits, but of difference in production (i.e. fittings screw together, but each kit is of different manufacture) so, aside from my dual carbs looking odd, with different jets, mounted, is my only worry getting needles to match? I know, how I might actually notice, wearing, in the needles; but do the jets even wear, out (much, besides, just their leaking?)



Thanks


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U

Yes

In general the jets wear a bit more than the needles going to oval overall as opposed to the needles that generally wear a flat spot toward the motor side (spring loaded side) of the carb and just in the middle of the needle travel. The biggest problem is air leakage around the throttle shafts and throttle shaft bushings. Strombergs have the added problem of diapragm failure.

Bob

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P

Both sides (dual carb) should be identical, with identical needles. One side squirts cylinders 1 and 2, the other squirts cylinders 3 and 4. Overhaul both sides at the same time (i.e, buy a complete overhaul kit. don't overhaul just one, but not the other). And, have both sides part of one complete system, not various parts from various systems from various applications over the years.

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