Valve Keeper Fit

[Walt Fricke]

The short stroke 2.8 I am slowly assembling has 8mm valve stems and guides in its 3.2 heads. The valves are standard aftermarket for 993 valves, so I purchased the 8mm Porsche keepers for them. I noticed that the keepers are a loose fit: when on, their edges touch and the keeper pair can be easily moved around.

I'm not the best at measuring, but I set up a dial gauge and I measured about 0.014" of play.

Anyone know why there should be so much?

I am grinding down the edges of the keepers so that they don't touch each other. The advice I have received (and believe) is that side to side play in the keepers will eventually put a bit of a burr on the valve stem. This won't necessarily cause problems - until it comes time to remove the valves, when the burr will score the guide. In fact, I am told it is an old hot rodder trick to use red Loctite on the keeper/valve/retainer assembly to reduce further all chances of movement.

Having to custom grind each keeper is tedious. Would be nice if they could just be installed.

[BURN-BROS]

I have to grind the keepers When using the stainless valves. And even then I get a burr. I have found that the grooves machined into the valves are not quite right but they have not failed even at 8700 rpm and aggressive ramp rates.

Do not leave any play or failure could result.

[Walt Fricke]

Well, after grinding down 24 of them, I now have them in pairs which I know are tight. But I have to keep track of them as pairs, as each one is a little different. But none touch when on the valve.

Had to file each one to remove a small burr on the outside.

Now I have to go back through all my heads and reset the spring height. As I suspected, narrowing even that little bit moved the retainer up. My spec is 39-40mm installed height, I had aimed for the middle, and this change means another shim (0.5mm) for most if the first head I checked is any indication.