BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: frogeye on 26 May, 2018, 14:01

Title: B31 cylinder head bolt threads
Post by: frogeye on 26 May, 2018, 14:01
Hi there,
Located a used b31 head. Seller says the cylinder head bolt threads are weak/loose. Is it possible to restore these threads?
Title: Re: B31 cylinder head bolt threads
Post by: AWJDThumper on 26 May, 2018, 17:20
In principle, you can insert Helicoils into cast iron but you would probably need to get it done at a machine shop - it might be best to contact one before buying the head.
Title: Re: B31 cylinder head bolt threads
Post by: frogeye on 26 May, 2018, 17:55
Yea, was thinking about that but where on earth could one get a british thread Helicoils?
Title: Re: B31 cylinder head bolt threads
Post by: ducati2242 on 26 May, 2018, 18:05
Quote from: frogeye on 26 May, 2018, 17:55
Yea, was thinking about that but where on earth could one get a british thread Helicoils?

Amazon do imperial helicoil kits
Title: Re: B31 cylinder head bolt threads
Post by: AWJDThumper on 26 May, 2018, 20:26
Quote from: frogeye on 26 May, 2018, 17:55
Yea, was thinking about that but where on earth could one get a british thread Helicoils?
They are readily available but I'm not sure whether the drill and tap that comes with modern kits are up to coping with cast iron - that's why specialist advice would be worth seeking.
Title: Re: B31 cylinder head bolt threads
Post by: paulm on 26 May, 2018, 23:15
The kit supplied by recoil is very good i have used it no problem
Title: Re: B31 cylinder head bolt threads
Post by: frogeye on 29 May, 2018, 02:35
Thank you!
Title: Re: B31 cylinder head bolt threads
Post by: wells01 on 02 Jul, 2018, 16:49
Hi
I have exactly the same problem with my 1952 B31.
I would like to try a Helicoil type repair but cannot find the thread size of the head bolts.
Any ideas.
Many thanks.
David Wells