copper sealing rings for pre combustion chambers ? anyone?

If that machine shop your dealing with is any good they should be able to spot face the pre-com seats to clean them up so they will seal. The sealing washers, steel or copper are just that, they are not meant to make up for missing material. 200 ft-lbs is 200 ft-lbs, doesn't matter what the washer material is.

When I replaced my precoms last Fall I purchased aftermarket from Dana at Florin. I think they were about $35 each. I also ordered the seals and rubber O rings from Florin, and they shipped those as well. None of which were more than a a dollar of so each. Give him another go around. He has been very responsive to me.

When I got them, I saw the seals looked like steel, a magnet did not attract them, but I went ahead and got copper from CAT instead of taking a chance. Again, less than a few bucks each, (actually, the fellow just gave them to me). I've not seen any issues with them post install....

Try CAT.

I use cat steel washers all the time, they work just fine.

Wibbdog-
Send me an email with your address-I was cleaning out the barn today and found the four precom seals I got from Dana at Florin hanging on a nail where I left them. I will send them to you if you forward me your address. I may even have the four O-rings. Happy to send those as well if I find them.

Bernie

Actually I would prefer to use the steel (on a good seal surface).
With the torque involved and the heating/cooling cycles it is likely that you will lose the torque setting when the soft copper extrudes.
I'd say there is a reason Cat has gone to the steel versions.

put alittle antiseize on both side of the washer helps to.