Peter,
Be very very careful using an abrasive compound or scrubber inside of
the SU damper chamber. The air seal formed with the piston rim is critical
for proper operation of the carburettor.
Identification of carburettor type is really quite simple, just
measure the internal diameter of the engine-side throat. The numbering
system is measured as eighth-inch fractions above 1". For example, a throat
measuring 1.50" would be 1" + 4/8th's of and inch, so therefore an H-4. Now,
as the years progressed, there were design changes from the original H
designation carbs. If the float bowl is off to the side, a small pipe
carries fuel to the bottom of the carburettor from the float bowl, and the
cover of the float bowl is held on with flathead screws, it's an HS
carburettor. If the float bowl is off to the side but has an extension
bolting it to the bottom of the carburettor, it is an HD (Damper) type. If
there is no external float bowl, and the bottom of the carb has a largish
square float bowl cast into it, it's an HIF (integrated float) type.
I don't know really which type is better, but there are several
opinions.
Greg
Greg Meboe meboe@wsunix.wsu.edu
Dept. of Mechanical and Materials Engineering
Washington State University, Pullman, Wa.
'85 XJ-12 H.E. (daily) '67 Spit-6 '74 TR-6
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