Exhaust valve retaining ring thread damage

[medat727]

Hello, my heads have excessive lower valve guide wear and will have to be replaced, the problem is that on one head, the ehhaust guide was missing it's retaining ring, ET122, someone had just smeared in some sort of epoxy as a replacement. After cleaning the threads from the epoxy it turns out that there is very little left in the way of threads for the ring. I am wondering what might be the best fix, make an oversized ring, run the guide without the retaining ring or some other fix. Thanks in advance.

 

[riptragle1953]

Bad memory again. Is there enough room alongside the outside of the threaded ring to drill and tap for machine-screws which, with small washers would overlap the ring edge and hold it secure? With a good interference
fit guide to head there should be no need for a retaining ring anyway. But, once again, we run into soft alloy castings.... or/and parts undersize.

 

[medat727]

Thanks, there should be enough room to do that modification, would two screws be enough or would you go with three or four? Even with the heads heated properly the old guides were still tight when drifting out, I've heard that some racers just dispense with the rings all together but that gives me pause being that the guides are so short to begin with.

 

[davidd]

Thanks, there should be enough room to do that modification, would two screws be enough or would you go with three or four? Even with the heads heated properly the old guides were still tight when drifting out, I've heard that some racers just dispense with the rings all together but that gives me pause being that the guides are so short to begin with.

The big port heads did not have lock rings. I have also run stock heads without lock rings on the racer, so do not over do it on the locking mechanism, just do good machine work and as Rip says, a good fit will do most of the work and the locking device is just a little insurance.

David

 

[riptragle1953]

I think two would be plenty unless you feel artsy and go for 3 at 120 degrees.