I am rebuilding a 1929 engine and am puzzled by the difference between the bolt holes in the starter body, which are 3/8", and the tapped holes in the crankcase which are 5/16" BSW.The 5/16"holes are badly worn and I was going to have them Helicoiled but am now wondering if it would be better to tap them out to 3/8" BSW. The other option is to make up some stepped bolts.
Any information or advice would be most welcome
Regards
Brian Hutchings

Brian,

Is it possible the starter belonged to an engine where the 5/16 bolts pulled out and so was drilled for 3/8??

I would encourage you to stick to your original plan and helicoil the threads, that way any if you any spares you need in a hurry remain interchangeable. Its worth taking this approach as far as possible with the whole car in my opinion because you can garantee the one spare you dont carry will be the part that breaks, at least then you stand a chance of borrowing bits if you are on a run. (granted i dont suppose many people carry a spare bacon slicer but you know what i mean).

A helicoiled 5/16 is probably stronger than a 3/8 in the ali anyway. Have a look at the WTI fastners website at : http://www.wireinserts.com/

They are british manufactured and give good support, they have all BSF / BSW in stock in a variety of lengths (very useful for the block / crankcase studs) and also make custom inserts and taps to suit. The sets are ~£15 for a tap, drill, 10inserts and the tools to fit them. Extra inserts are ~10p each. Highly recommended.

Regards

Rob

Thanks for that Rob. I decided to sleeve the bracket back to 5/16" and Helicoil the crankcase.
Thanks also for the information about the Helicoil supplier. The lowest price I could find was £24 for a kit but as I need 3 different sizes of thread, I am taking it to Ian Bancroft in Grantham who charges £3 each to fit. I need 11 fitting so it is cheaper (and probably safer) to let him do it.

Don’t forget to fit the stepped locating spigot next to the left hand bolt---its often missing

Brian,

I have successfully fitted studs (these can be bought stepped or standard), in place of the bolts on these type starters and also the later (1930-32??) type which come back over the gearbox. I have found that years of taking out and replacing these bolts has a negative effect on the life of the thread into the crankcase (one such thread disintegrated whilst I was in the north of Spain, leaving me to hand crank the engine until I got home!). It is a bit tricky getting the bacon-slicer type over the long stud, but possible.

Good luck

Ruairidh

Thanks for the reminder Ian; as it happens the dowel was missing so I have made a new one.
Regards
Brian

I thought about studs Ruairidh but wasn't sure about the clearance. Anyway, as mentioned earlier, I will have the crankcase helicoiled and have already made up some sleeves to reduce the bolt holes back to what was, presumably, their original size of 5/16"
I might say that the starter hardly gets used; mainly if I stall at junctions and traffic lights although that dosn't happen as often as it used to, thankfully!
Regards
Brian

I had just the same problem with my Chummy 30 years ago. Robin Townsend fitted a helicoil for me and it has been fine ever since. I fully agree with Rob - helicoils/thread inserts are a much better solution than stepped studs which I regard as an unpleasant bodge, only to be used when absolutely necessary. I try to dissuade people from fitting them.

David