Thanks Gray Beard. Since I wasn't the one to replace the bearing I don't know if the shield was removed or not, but I can probably find out.

As for FAI fuel I really don't know. I had a friend (now deceased) who had the same engine with the next serial number and feel quite certain he didn't use FAI fuel.

This is a strange engine. We got it to run over 5 minutes wide open without the cowl and tied to the ground - since then I haven't been able to get more than 3-4 minutes and it gets VERY hot. I'm still using the same fuel - 15% nitro. This may be a bit too much for this old engine but it sure puts out a lot of power. I don't have any tamer fuel nor do I have any castor oil.

I'm going to pull it out of the plane (see avatar) and put it on a test stand to eliminate any plumbing problems or foaming problems.

Several have suggested that the fuel could be the problem - lack of cooling oil content. I'm wondering if that bearing is siezing. Your's was the first to suggest this as a possible source. I hate to trash this engine and fork over $$$ for a modern one - like an OS.

Thanks again.
Phil