Hi, can anyone tell me the diameter of the inlet ports where the carbs flanges bolt up to on a 1966 A65L head please. Roy

Hope this helps..

Thanks Ian

Hi, Ian sorry to be a bother are the A50 inlet ports the same diameter or different I seem to recall putting a 32mm gasket over the carb mounting studs but could still feel the cylinder head sticking out, if they are smaller could I have a A50 head on A65 barrels. thanks Roy   

Hello Roy.. Some confusion from my attachment which was taken from A65 workshop manual.. I have been told that A50 head would not fit on A65 barrels as centre bolt in different place..
The dimension listed previously could be the diameter at the valve not at the carb flange. Apologies if this has confused you.

Hi Roy, I haven't seen the full page Scan from Ian's reply but I can assure you that the inlet port where the carb meets it is 1 5/32" which is a gnats leg short of 30mm (about 29.5)

64-65 had taper ports, they started at 1 1/8 and tapered down to 1 1/16 (this is close to 28.5 down to 27mm)

From 66 though to the OIF models, all the ports were 1 5/32, although by 67 with the introduction of 30mm concentric carbs, the port sizes remained the same. Some of the OIF heads were this size and some were 30mm the castings are quite noticeable in difference, as is the finish on the aluminium and the part number also. I could show you but all my ports have been fettled with in one way or another so couldn't give you an exacting size, ian has one of these 30mm port heads on his OIF.

As a note before someone points out. The Mk2 and 3 spitfire also had the same head their GP carbs were also 1 5/32", however in 68 when they fitted concentrics they splayed the port to 32mm. There are some notes on the factory bulletin page which I think was released in 67 on how to do this on earlier heads.

In case your wondering if you have an A50 head on there... you haven't, otherwise you wouldn't have an A65 barrel either, the A50 centre stud is in a different location (more central) than the A65, from memory it's about half a bolt hole different.

A50's used different port sizes also though, the early cyclones had tapered ports then they went to straight ports like they did on A65, but these are both 1 1/16" at the mounting.

Thank you Allan for your clarification.. I should have attached this copy from the workshop manual, so many apologies again Roy.

Thanks Ian and Allen you two have explained every thing, top notch info. Roy