Valve Spring Free Length

I'm cleaning up a Combat head and after striping it, I measured the valve spring free length. I was surprised by the results. The outer springs measure 1.635" but the workshop manual says 1.618" so they are longer than the manual says. However, the inner springs measure 1.470" but the workshop manual says 1.482" so they are shorter than the manual says. I searched all my service bulletins expecting to find an update but I didn't find one. At this point, I'm simply interested - I'll probably install new springs regardless.

Tolerances on free length springs are not super precice. You really care about the force when deflected. Your springs are probably ok but new ones are not expensive for pease of mind.

Standard springs are £28 a set from AN, so if you already have it apart.....bunging in a new set is wise anyway....

But free length is just a guide, a useful one sure, and if the have sagged dramatically they are past their best.

If you wanted to be precise you would set installed height to a chosen seat pressures.

So assuming that you have standard valves/springs and cam and they haven't done a high mileage, they are probably just fine.

But if you aren't comfortable, just replace them.