Group,
FYI.........
My first tune-up on the '70 Spitfire included replacing the air cleaner
elements which were from the round, chromed (metal mesh) aftermarket air
cleaners. After resetting mixture and balancing both carbs, when I began to
replace the circular back plates of the air cleaners to the same carbs they
were removed from, I noticed that the plates appeared to have been swapped -
wrong plate on each carb!
On the SU HS2's (can't speak for later SU's) as used on Mk3 Spits, there is a
non-threaded hole in each carb that's about the same size as the air cleaner
mounting holes that sits just above and to the left of the left threaded bolt
hole. The air cleaner gaskets have two cutouts (both sides) in them for this
hole so they can mount to either carb....but, the chromed air cleaner
mounting plates have only one cutout for the hole so they definitely are
right/left plates!
I don't know what the hole in each carb does but my guess is that it helps
control damper action - anyone know? In any case, plugging it completely is
easy to do with these aftermarket air cleaners if the plates are swapped and
I have to believe that performance is affected in some way!
My car runs better overall but I don't know how much is attributed to the air
cleaner discovery or my tune-up effort:)
Cheers,
Chip Krout
'76 TR6 CF57822U (Being Reborn For Y2K)
'70 Spit MkIII FDU78512L (Decent Driver)
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