Sump studs size and thread

[Colin Wilks]

Don't forget to drill the sump to suit those two bolts.

I think Ruairidh was talking about sizing the hole in the sump itself. Bit of a bugger if you've got it all fitted bar your new fat jobs and then you realise the new bolt won't go through.

Have to say I can't see the difference between drilling and tapping 5/16" standing on your head and fitting a helicoil so as to keep all the bolts the same. Plus if you make a mess of the drilling and tapping you are starting to run out of meat in the crankcase to then helicoil that hole!