Author Topic: Valve spring wire gauge/length differences?  (Read 848 times)

Offline jachenbach

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Valve spring wire gauge/length differences?
« on: 02.12. 2014 23:52 »
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?

Online bsa-bill

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Re: Valve spring wire gauge/length differences?
« Reply #1 on: 03.12. 2014 08:50 »
Quote
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
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online muskrat

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Re: Valve spring wire gauge/length differences?
« Reply #2 on: 03.12. 2014 18:50 »
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
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Offline jachenbach

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Re: Valve spring wire gauge/length differences?
« Reply #3 on: 04.12. 2014 01:16 »
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.

Offline wilko

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Re: Valve spring wire gauge/length differences?
« Reply #4 on: 04.12. 2014 21:23 »
 So are iron and alloy valves the same length?

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Re: Valve spring wire gauge/length differences?
« Reply #5 on: 05.12. 2014 08:47 »
A10 iron head valves fit in A7 alloy heads.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Offline wilko

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Re: Valve spring wire gauge/length differences?
« Reply #6 on: 05.12. 2014 21:23 »
Trying to fathom the spring length difference if they're the same length?