A10 and A7 valve springs

[Pete A10]

This is probably a stupid question but are the valve springs on an A10 the same as an A7. I've bought what are meant to be a set of A10 springs but they are too small in diameter to fit on the valve cups.

[JulianS]

A10 Golden Flash, A7 and A7 Shooting Star springs are the same parts. A10 Rocket models use a different spring.

[Pete A10]

Thanks Julian
What confuses me is that all the other parts seem correct for a Golden Flash. Cup is 67-0033 (I had to buy one new one so this is definite), it is an iron head 67-1065 (cast on head) and valve springs are 67-0440/0439. but the springs don't fit. Do you know if Road Rocket springs will fit into a Golden Flash head - if they are bigger I might try them.

[JulianS]

The Rocket springs use different cups collars and collets.

They are larger diameter and the Rocket  rocker box is relieved on the inlet side to ensure sufficient clearance.

They dont seat nicely in the iron head seats and collars I have tried it.

An old set of iron head springs I have measures about

Outer spring O/D about 1.32 inch  I/D 1.02 inch

Inner  O/D about 0.84 inch  I/D 0.82

New lengths should be 1 7/8 outer  1 17/32 inner (given by BSA)

Might give you an idea if you have been supplied the correct springs.

[Pete A10]

Measuring the old set that came with the bike I get outer OD 1.390; ID 1.084 and inner OD 1.067; ID 0.818. The new ones are outer OD 1.309; ID 0.984 and inner OD 0.828; ID 0.627. All a bit betwixt and between but I think the new ones are incorrect so I'll chase the supplier. Surprising really as the springs were made for Wassel and supplied by a reputable outfit.