BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: MARKIE2CUPS on 21 November, 2017, 09:25:50

Title: A10 valve / tappet clearance
Post by: MARKIE2CUPS on 21 November, 2017, 09:25:50
Hi,
I have a 1957 A10 golden flash and wondering if someone has any suggestions with regards tappet clearance. I've researched the normal sources set them up to 10 inlet and 16 exhaust starts and runs but I've not been for a run out yet because I know it has high commission pistons and I was told by the previous owner a spitfire high lift cam. My question is would either alter the clearance needed? I've sent myself boggle eyed researching and going round in circles LOL. Any ideas would be great
Title: Re: A10 valve / tappet clearance
Post by: JulianS on 21 November, 2017, 10:29:13
Not seen a factory figure for iron head and Spitfire cam. All the Spit figures seen for light alloy heads.

I ran such a combination for a few years and ran on 8/10 thou inlet/exhaust no problems. Also tried Eddie Dow recommended figure of 10/12 thou. Also fine no problems.

Attached is factory service sheet which has been annotated but do not know by whom.

I think you try various settings and see what is best. 10/16 will probably rattle a bit.
Title: Re: A10 valve / tappet clearance
Post by: MARKIE2CUPS on 21 November, 2017, 11:15:10
Hi,
Thanks for the reply. And yes does rattle a bit but being a Brit bike novice unsure if this was normal. I forgot to mention that it has a alloy head I don't know if this makes a difference?
Title: Re: A10 valve / tappet clearance
Post by: JulianS on 21 November, 2017, 11:34:33
You have a choice of any of the above - try and see which suits best.

Eddie Dow tuning notes attached.
Title: Re: A10 valve / tappet clearance
Post by: MARKIE2CUPS on 21 November, 2017, 11:48:48
Many thanks,  looks like good reading and seems to reflect a lot on my bike too. Off for a bit more tinkering I think now
Cheers
Mark