Valve Springs

[spottycat]

Hi - I have done a search but probably more confused about the length of valve springs. I have a 1961 A10. I think it's original but whether it qualifies as a SR or an RR or just an A10, I'm not sure. However, as part of my rebuild I thought I'd measure my valve springs but they do not correspond with any of the dimensions I can find on the forums. The larger springs have an average length of 52.5mm - 2.067" and the smaller spring 37.4 - 1.472". I figured I would replace them anyway but have seen listed springs for A7 /A10 or for Super Rocket/ Road Rocket. I found these on Feked, listed for A7/A10 Iron head, so maybe these are the ones to go for because I do indeed have an iron head. Calssicbikesshop have other springs listed for SR RR 1958 on or just A10/A7 springs. Can anyone clarify this for me please?

I should add that the engine number begins DA10, so I assume it to be 'just' a GF. However, I know that it has a 356 cam, though I have read these were sometimes fitted to the later models but could  determine which springs are needed.

Cheers, Chris

Valve Spring Set - BSA A7, A10 (1947-62) Iron Head models
(Terry no.VS 454) Valve Spring Set.
Includes 4 inner springs (67-0440) and 4 outer springs (67-0439)

[Swarfcut]

 With no response to this conundrum so far and with some used springs to hand, I'm now just as bemused as the rest of you.

  Quick Measure, Cheap Caliper... Measured at the cut and ground  flat ends.

  Big used springs   45.5mm, 46.1mm, 44.8 mm 45.7 mm  and another set... 47mm, 46.8mm 47mm 47.4mm

  Small used springs   34.7mm  35.1mm (Just 2 from this set).  2nd set as above  38.6mm 38.9mm  38.3mm 38.9mm


 So looks as if I have a right mix, some look definite wrong 'uns. All were offered as suited to Iron Head. The " another set" lot came in an old Terrys VS454 box, probably worth more than the springs.....

 Swarfy.

[spottycat]

Thanks. I am not sure why mine are different - the longer spring at 52mm might be an old set intended for an alloy head, which started out at 54 but  I think the Terrys VS454 are my best option as they are correct for an iron head. Cheers

[chaterlea25]

Hi,
Posting a photo of what you have valve wise and caps and collets  would help? Because it's unknown what a previous dpo did
Iron head valves have a plain groove, 
Alloy head have a semi circular groove, and different caps , collars and collets
There are some previous topics on the forum to search for as well.
I have alloy head springs that I can get measurements for later, time permitting

John

[muskrat]

G'day Chris.
The only info I found was a W D James list.
Cheers

[spottycat]

Thanks guys,
charterlea25, here is a pic of one of the valves.

[Swarfcut]

 Looks the correct valve type for the iron head. Original valves will have a BSA Piled Arms Logo. One to hand has the part number and IN stamped as well. In this case it's an inlet valve, 67 531 for a Star Twin/Shooting Star '54/57 according to the book.

 The valve collet you have may not be is correct for this valve.  Is the top edge inner surface raised to fit a groove in a valve stem? Your valve takes plain collets as noted by CJ. Sadly without an education in Classic Vocabulary I could not find the words to describe it better. Maybe a trick of the light but it looks to have the extra bit.

 If you can find it, Drags has a valve chart showing stem length and head diameter. Try this link, it is reached via a Technical Information heading in the BSA section of the site. It is by no means comprehensive. Sod's Law!   

    .https://draganfly.co.uk/wp-content/uploads/data/pdf/valves.pdf

 Alpha Bearings in Dudley  were aftermarket and OE suppliers of Valves and had comprehensive listings of applications, now part of Autocycle Engineering their old website may still be available for more info.

 

 Swarfy

[spottycat]

Swarfcut, thanks. I see what you mean about the collet but it is a trick of the light; the collets are plain. I try to research things as best I can because you never know what people have done to these old machines over the years. I think my best choice is to go for the valve springs listed on Feked as for the iron head, which hopefully will match the lengths listed in Roy Bacon's  book. Thanks all for you rinput

[chaterlea25]

Hi spotty,
Do not rely on Bacon's book it has more holes than a colander in it . Haynes says spring lengths are 1 17/32 and 1 7/8  for all models  
It's not all about spring length, wire size and number of turns is equally or more important

John

[spottycat]

John,

Those measurements fit with the Bacon book. At the end of the day I am limited on what I can buy. Sets seems to be for iron head or alloy head, so I think it has to be the iron head set, which I think are right.

Chris