Should I replace my valve springs ?

Hello all

My engine top end is apart.
Definitely new valves and either new valve guides or K-Line sleeving the existing guides.

Here is my question (and I come from working on a lot of classic British cars where I never replaced valve springs.)

Should I replace the valve springs? None are broken.

I know that aircooled means all runs far hotter

Thanks

Dennis

At the risk of sounding butt stupid, there are two schools of thought:
1. Replace everything all the time, just to make sure.
2. Measure, look for wear, and only replace as needed.

There are specifications on relaxed or free spring height.
Also specifications on spring deflection or height under a fixed load. If your springs meet these tests, there is no need to change them.

I suspect old valve springs are frequently removed without being tested. And new valve springs are frequently installed without being tested. The second seems more flawed than the first.

We have all heard stories about cams being wiped out. Installing springs with excess spring pressure should be avoided. One more reason to measure what came out and what goes in.

DennisMo said:

Hello all

My engine top end is apart.
Definitely new valves and either new valve guides or K-Line sleeving the existing guides.

Here is my question (and I come from working on a lot of classic British cars where I never replaced valve springs.)

Should I replace the valve springs? None are broken.

I know that aircooled means all runs far hotter

Thanks

Dennis

Click to expand...

I inspect them for rust and/or dings/marks - if any, I replace them. Then I measure the free length of the outers and record each and the inners and record each. If the inners are all the same length and very close to the workshop value and the outers are the same length and very close to the workshop value, I reinstall. If any of those cases are not met then I replace them. I check the new in the same way before installing. So far, the sets from AN have all been good.

Thanks for all the advice. Dennis

Mine were well below manual stated free length. The AN ones were spot on and noticably taller. Why would you go that far and not take the last step?

After my bike had been stored for 30 years, I was worried that one of the valves could have been in a fully open position for all that time, and could have permanently been compressed and shortened.

Removed the springs, measured them, one was massively under the permitted height, others were a bit too short, so I changed the whole lot.

MichaelD said:

After my bike had been stored for 30 years, I was worried that one of the valves could have been in a fully open position for all that time, and could have permanently been compressed and shortened.

Removed the springs, measured them, one was massively under the permitted height, others were a bit too short, so I changed the whole lot.

Click to expand...

I agree with Fast Eddie. These garage/ barn bikes are 50-60 years old. New springs are not terribly costly...more peace of mind.

That makes sense. I will order replacements

Engine set £32.50 plus taxes/shipping. Why not?