A65 Spitfire carbs

[Spitfighter]

I am slowly getting higher up the engine with the rebuild and will soon have to think about the carbs.

This (mostly) '66 Spitfire came with two tatty old concentric carbs in a separate box which are marked 930 L and R and which I do not feel inclined to refit. They probably didn't belong to the bike. Nor would I fancy replacing them with the GP originals given what I hear about them, but some new concentrics sound like the way forward.

However the two cylinder heads (one on the bike and one in the said box) both have carb openings which are only 28mm across which suggests they may not be Spitfire heads unless the GP carbs had the smaller opening.

I have spoken to the man at Amal who thought the opening should be 32mm and I suppose it could be bored out, but talking about fitting 28mm concentrics sounded as though it would work mostly just as well.

Any advice, wisdom, info or suggestions before I commit to anything, sell the cat etc and buy some new carbs?

[Airman49]

I have a -68 Spitfire and 32mm Concentrics is what was standard. For the -66 I don't know, but 28mm sounds not right to me. But I'm not an expert on the -66 Spitfire
Checked my workshop manual and for the Spitfire MkII the carbs was Amal 516/103GP (RH) and 516/120GP (LH), diameter on the outlet it does not say.
1968 specifications: The Lightning had 30mm Concentrics and the Thunderbolt had a single 28mm.
So I think a pair of 28mm Concentrics will work.