Float Chamber to Carb Body Banjo Bolt Thread Size

[SteveW]

I've been rebuilding the SU carbs on my TC. All was going well, with new internals installed where needed and the suction chamber and float chamber have polished up nicely.

However, the threaded hole in both carb bodies where the banjo bolt goes that holds the float chamber on are badly stripped (not by me). I'm going to need to insert a helicoil. What is the thread size and type as it's not obvious when comparing it with my tap and die sets? Hopefully the body of the carb is thick enough to take the helicoil (BTW, I know that it cannot go in further than the fuel hole).

[Rob Reilly]

Every banjo bolt on the SU carbs is BSPP threads.
Measure the OD and look up a BSPP thread chart.

I have no idea if you can find a BSPP helicoil or Keensert. Maybe in the UK.

For stripped threads, either chase them with the correct tap, or fill in some JB Weld and then tap them.

[Steve Simmons]

My notes say 7/16-18 BSF for the lower bolt to attache the bowl to the body.

[Rob Reilly]

My mistake, I was thinking of the float bowl caps.
7/16-18 BSF is correct.