Thread ID flywheel pit cover

[Ivor Hawkins]

help! I don’t think someone has drilled out and retreaded the bolt holes holding down the flywheel cover, but I’ve tried both Whitworth and BSF bolts and no luck...can anyone let me know what the standard size should be?
Ta!

[Alan]

1/4BSF

[Ivor Hawkins]

Thanks Alan, I’ll measure up and see if they are still standard...and order some 1/4 bsf set screws just in case!

“Friends” comes to the rescue again

[Robert Leigh]

Mine are all 5/16" whit for the 'tin' cover, but there are 5/16" BSF to hold our mag Chummy starter.
Robert Leigh

[Chris KC]

Sorry Alan, I'm with Robert here! Mine are 5/16".
That's not to say they haven't been enlarged, but every 1/4" screw in the case is BSW as far as I'm aware...

[Alan]

Ah I’m talking of the clutch cover plate not the bit of tin that covers the bell housing. In that case it is 5/16 BSF on eRly engines and whit on the later ones. Sorry for the confusion.

[Ivor Hawkins]

Thanks fellas, yes it's the tin cover I'm talking about, so I'll check that it's 5/16 whit . I have a feeling someone may have stripped the threads in the past...how they've managed that I'll never know...

[Ian Williams]

I had an engine through my hands where a previous owner had helicoiled a number of stripped 5/16" threads in the crankcase with M8 inserts, but used 5/16 UNF inserts for the head studs! Gets very confusing when people use non standard threads.