What valve springs should i choose?

[Caprimaniac]

We are indeed going racing and we will indeed do all engineservice & rebuild in house.

Why don't we need some experts to do the work for us? For one, we're amateurs. Which means; we go racing when everything is working & in order. We're not going to every race, whatever the costs. There might be some person in this part of the world that could do the service needed, but this person I have not heard of or met yet. You see; there's a HUGE difference between US and the rest of the world regarding professional engine builders. Here in Norway, you don't come by them every day. And car racing is not very large; there were alot going on in the 70's, but calmer these days. But; it's getting busier. Besides; I am semi- pro, which means all experience is good experience. I admit the only downside is the lack of some basic machinery for skimming heads, cylinder boring, centerline measurements etc. fortunately, we have good friends helping out on such matters.


Let me come to the point here! Long since I posted and something has come up that I'd like to ask the experts.

While dismantling the Vic Jr. heads I discovered that under the valve spring discs, there are shims of different thickness for the exhaust VS inlet valve.

The springs and hardware for ex and in are identical and as I understand effective installed gheight should be identical. Have they taken into account temperature differences between and hence the effective length of the two? In other words; should you consider factor of valves stretching or being shortened while checking installed height on (aluminium) heads?

(I would assume that the aluminium is swelling more than the steel valve, and more at the ex than on the in valve?)

The other approach is: Inlet valve needs a little more preload, hence the thicker shim, shorter installed valve and higher closed spring rating, to account for the heavier valve. (2.02 VS 1.6")

would be interesting to know, as assembly of new valvesprings start very soon.