The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: lefty on 07.03. 2009 17:28

Title: late a7 valve spring lengths
Post by: lefty on 07.03. 2009 17:28

hello all,
anyone out have the measurement for what unsprung 61 A7 iron head valve springs should be? apparently most of the new ones on the market fade quickly and are incorrect lengths to begin with....?? i have a good stock of used ones, but no info to guess if they are sagged beyond use or not.

anyone tried sleeving down an a10 barrel for use on an a7? if they were the same original casting this might work...the a10 barrels come up all the time on ebay.ca, but a7 seem rarer

leif

Title: Re: late a7 valve spring lengths
Post by: trevinoz on 07.03. 2009 20:59

A10 barrels are taller so would be impractical
  Trev..

Title: Re: late a7 valve spring lengths
Post by: bsa-bill on 07.03. 2009 22:13

for late models valve spring length is the same as A10
67-0440  -inner spring (1 17/32) inch
67-0740  -outer spring (1 7/8) inch

Rocket springs are different part number ( are they not a lighter spring )  and might be a different length although  Mr Haynes states the same length for all models.

All the best - Bill

Title: Re: late a7 valve spring lengths
Post by: dpaddock on 09.03. 2009 14:49

RR, SR and RGS springs are 2" and 2-1/8", respectively, per Roy Bacon.
     David