Valve spring wire gauge/length differences?

[jachenbach]

So.... yesterday I cleaned up a head and went to reassemble it. Thought I'd measure the length of the springs and found they were all much longer than Haynes or Roy Bacon say they should be. So I got a couple other sets and found out they were all the same length, but some had much heavier wire inner springs than others. If I recall correctly, the heavier springs went with the "HHC" engines, but the length concerns me. Are Haynes and Bacon wrong?

[bsa-bill]

If I recall correctly, the heavier springs went with the "HHC" engines, but the length concerns me. Are Haynes and Bacon wrong?

Somehow I thought Rockets had lighter springs, or longer springs or both, I know they are different, It's been a while since I fitted them

[muskrat]

My Bacon book says 2.0" & 2.12" for SR & RGS '58-'63. All others (including A7SS) 1.53" & 1.87". For wire size and # of coils I'll have to dig in the bottom shed later.
Cheers

[jachenbach]

Thanks, I feel better now. Mine are all measuring 2.1 inches. I was looking in BSA Twins and Triples and the Haynes manual. After your reply I pulled out BSA Twin Restoration and as you say, he lists longer springs for RR, SR, and RGS. As all my heads are alloy, I expect they are all off these models. I've not seen any numbers, but here in the USA everyone seems to think they need bigger bikes and more power than they can actually use. I expect the high performance models far outsold the A7 and Golden Flash.

[wilko]

 So are iron and alloy valves the same length?

[muskrat]

A10 iron head valves fit in A7 alloy heads.

[wilko]

Trying to fathom the spring length difference if they're the same length?