A7 Special SU carburettor replacement

[Mgibson]

My A7 special engine makes 28 bhp on the Dino but carb is worn so difficult to tune reliably . It has a AUC 980 SU fitted from a 60s A40 . I am thinking of refurbishing or replacing the carb so would appreciate advice on alternative carb jets and needles, HS2 seem readily available at a reasonable price  refurbished .

[Speedex750]

Hi Malcolm,

I think you'll find the AUC 980 is already an HS2. When you say it's worn do you mean the jet and needle or is the butterfly wobbly as well? If the former a new jet and needle are easy to fit insitu. Check the number stamped on the shank of the needle to see if it's standard A40 or has been previously changed. If your engine has been already set up on a dyno the needle is probably pretty close to what you need and could only be bettered by another dyno session. If the butterfly spindle is wobbly it'll only show up at tickover and your ultimate HP won't be affected, a drop of thick oil onto the spindle at tickover shows up how much it's leaking and weakening the mixture.

Dave

[Stuart Giles]

If the carb is from a 60's A40 it should be an HS2.  The HS2  rebuild kit from Burlen has all the wearing parts in it.
http://burlen.co.uk/rebuild-kit-for-hs2-...11347.html