Greetings all.

Re-assembling a Cooper 997 head after getting it machined. Measured the spring (s) length, and they are all around 4". The book says they should be 4 & 1/2". Would this effect the performance much?

Alex.

Assuming you mean they're 4" uncompressed, and not installed in the head, they're either shorter springs than standard, or they've lost 1/2" of springiness. If they've lost springiness, then valve bounce will set in a lot earlier than if they were new

I'd ditch them for newies - good springs are cheap

_________________
did I tell you that I won a trophy?

Thanks Simon.
Sounds like a fresh set will make sure all's good.
Cheers
Alex.