What valve springs should i choose?

[blykins]

Unfortunately, install height is not always the exact same between intake and exhaust valves. One valve may be shorter than the other....one valve may receive a different angle valve job than the other, etc. You should always check between the two.

You are correct in that the exhaust valve is lighter and thus doesn't need as much spring pressure. However, that side is not one to be experimenting with, as if your exhaust valve floats, there's a very good chance that it will contact the piston as it's coming up and the end of the exhaust stroke.

If I were in your situation, I would measure each install height, calculate what you want your open/seat pressures to be, lay your shims out for each valve, then assemble.

[Caprimaniac]

Originally Posted by blykins

Unfortunately, install height is not always the exact same between intake and exhaust valves. One valve may be shorter than the other....one valve may receive a different angle valve job than the other, etc. You should always check between the two.

You are correct in that the exhaust valve is lighter and thus doesn't need as much spring pressure. However, that side is not one to be experimenting with, as if your exhaust valve floats, there's a very good chance that it will contact the piston as it's coming up and the end of the exhaust stroke.

If I were in your situation, I would measure each install height, calculate what you want your open/seat pressures to be, lay your shims out for each valve, then assemble.

Yes, Brent. I totally agree with you; it will have to be checked for every valve / spring installed.

The dismantled heads were put together at Edelbrock. All the exhausts had same shim, which were different from the ones, also all identical, at the inlet. I thought therefore it was one reason for this. anything of what I mentioned or, as you say, a difference in length or valve seat depth.

I checked the Summitcatalogue just now, and they don't list any different lengths on the two... Oh, I will have to measure to know, anyway...

And I will not experiment with less spring preassure on the exhaust side, promise!

Thanks again