Valve Stems, Keepers and Spring Retainers

[chris_seven]

As we haven't been too happy with the valve guides we have been buying we are going to have a batch of Colsibro guides manufactured and we though it was worth looking at the idea of using valves with 8mm stems.

I have seen posts that suggest that this reduces heat transfer and others that say the inertia and gas flow improvements are marginal but also others that seem to have successfully used this design.

The subject of keepers is also relevant and the 3 groove stock keeper seems to have issues.


I think that in general the three grooved keeper can be described as 'unclamped' and when used with high lift cams can allow a small movement to occur.

Modern designs of performance valve seem to use a single groove with a clamped keeper which I believe clamps the valve very effectively.

Shrick make single groove keeps to a very high standard with a single groove for about $40 for 24 and these seem quite interesting.

I think I saw a thread where Extreme Heads were using 8mm valves with single groove keepers.

Is there any real downside in using 8mm valves and clamped keepers?

It is also becoming quite common to use Titanium retainers but these are relatively expansive and Ti can be susceptible to galling which could occur in this application.

On Lotus Twin Cam engines we used spring retainers mande from 7000 Series Aluminium which were hard anodised and never had problems.

They were very light and quite cost effective.

Anyone used Aluminium retainers?

[docrodg]

I tried those in a high-rev chevy engine I built. Was going to use Ti retainers but the owner found some aluminum ones and wanted to try them. They were crap and stripped out on the first hard pull. Granted we are talking a different engine and spring pressures (over 500 as I recall).

[Spenny_b]

Chris, I'm using the Schrick stuff, 8mm valves but with the 3 groove keepers, but only with fairly mild cams (964 n/a in a 964 turbo application). Also went with the Ti retainers. Am building the engine as we speak, so can't comment on effectiveness just yet.

I believe Chris Carroll @ TurboKraft is using the ally retainers, but of course, there's aluminium and aluminium, as he was keen to point out to me. The only reason I didn't go with them was that I wanted the guy who ported/rebuilt the heads to supply everything in a one-stop-shop.

[chris_seven]

Originally Posted by Spenny_b

Chris, I'm using the Schrick stuff, 8mm valves but with the 3 groove keepers, but only with fairly mild cams (964 n/a in a 964 turbo application). Also went with the Ti retainers. Am building the engine as we speak, so can't comment on effectiveness just yet.

I believe Chris Carroll @ TurboKraft is using the ally retainers, but of course, there's aluminium and aluminium, as he was keen to point out to me. The only reason I didn't go with them was that I wanted the guy who ported/rebuilt the heads to supply everything in a one-stop-shop.

I have been looking at 7085-T7651 which is about as strong as it gets. The angle of the keeper will also have an impact but I am coming to the conclusion that Aluminium may be too risky.

I have found a shop close by that can make then in 6AL4V and then plasma nitride which will stop any galling.

I think that a clamping single groove keeper sounds like a good idea and the Shrick parts seem very cost effective.