BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: gusmagicbus on 05 February, 2017, 20:32:36

Title: C15 Head Gasket Advice
Post by: gusmagicbus on 05 February, 2017, 20:32:36
Hello,

I'm rebuilding a C15 SS80 1964. I've measured the thickness of my cylinder head gasket (~.039 - .040") and bolted the head onto the barrell without the gasket and measure the thickness of the gap which is about ~.035 - 0.38 depending on which corner you stick the feeler guages in. Hence, compression on the gasket could be as low as .001" in one section.  I think the head has probably had one too many skims, and I am worried that the gasket will blow (or leak oil).

I guess a slightly thicker gasket would be good, does anyone know where I can get one off these or if there is another trick commonly used. Or even if 001" gasket compression is ok.

Thanks
Steve
Title: Re: C15 Head Gasket Advice
Post by: TTJOHN on 06 February, 2017, 13:15:03
Steve,
 I have a spare solid copper gasket that came off of a C15, your quite welcome to it for the price of the p+p, the other trick with these is to put a thicker gasket under the barrel, or double up.

TTJohn
Title: Re: C15 Head Gasket Advice
Post by: gusmagicbus on 09 February, 2017, 00:16:24
Hi TTJohn

Sounds like an excellent offer, thank you. How do we arrange that then!?
Title: Re: C15 Head Gasket Advice
Post by: TTJOHN on 10 February, 2017, 09:33:49
Steve, you can e-mail me with your address to Jomichael@aol.com

Regards TTJohn
Title: Re: C15 Head Gasket Advice
Post by: Arthur on 11 February, 2017, 11:24:20
Steve.

It does sound as though you head has been skimmed too far - I think 1 thou of gasket compression is going to be too low and I'm sure would cause problems. I think 5 thou would be the minimum required. My old C15 gasket is about 38 thou and a new one might be a little thicker but still not thick enough.

The simplest solution might be to get 4 thou skimmed off the top of cylinder liner - this will increase the compression ratio by a small amount but shouldn't be too significant. The alternate solution would be to get a bespoke copper head gasket made of the correct thickness, if possible - there are a lot of companies that advertise this service.
Title: Re: C15 Head Gasket Advice
Post by: Arthur on 11 February, 2017, 11:43:45
Just found this 47 thou thick C15 gasket advertised, albeit in the US. If the standard one is normally 40 thou thick, one like this might solve your problem.

http://www.bsaunitsingles.com/item.wws?cpubcode=BSAU&sku=40-0140