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Valve spring wire gauge


nkt267

Well Known and Active Website User
VOC Member
Hi all.
Can anyone tell me the diameter of the wire for the hair springs on a Series A.
I've been told that they are suitable for a 1930's Sunbeam..I have a feeling that they may be a bit on the heavy side. Does anyone know what the seat pressure of the springs is please..
Many thanks John
 

A_HRD

Well Known and Active Website User
VOC Member
0.160" touring
0.170" racing (usually TTR and TTC bronze heads).

But those gauges may not be available these days, so most replacements are as close as possible to this (4.5mm?).

Sorry, I can't find my note about seat pressure at the moment...(!).

Peter B
 

nkt267

Well Known and Active Website User
VOC Member
Thanks Peter..The wire gauge matches what I would need.
The combined spring pressure on the seat with standard Sunbeam springs is 140lbs which I think is too much when new cams are no longer available..The new ones being made for us now are lighter but i don't know what the wire gauge is yet as Sunbeams used 0.160" and 0.185"..Just looking for alternatives..John
 

A_HRD

Well Known and Active Website User
VOC Member
John, I found some more info if it's of any use - it's presumably for one spring:

For 0.160: at 3/4" installed height at the valve = 50-55 lbs. (0.170 = 57-63 lbs)
For 0.160: at 7/16" installed height " " " = 65-70 lbs (0.170 = 75-80 lbs).

Peter B
 

nkt267

Well Known and Active Website User
VOC Member
Thanks Peter. I have just loosely assembled my Sunbeam head and I will compare the installed height with your figures. 2 x 55lbs will certainly be better than 2 x 70lbs that I have now..
 

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