Doing valve guides for the first time (in my life) and determined to go back with cast iron. Seems the OEM style are out of stock most places for the sizes I need.

Here's my question - what's with the lock rings on some of the cast iron guides? Just a stop for depth?

And some (manganese bronze) have an o-ring and lip. Looks to me if they are fitted correctly in a good bore, no way they can leak.

I realize some photos don't exactly match an item for sale, and the Twin Cams that use 7mm valves do use a guide with lock ring. Don't think the lock rings on an Evo guide would matter even if they were removed, so long as the it's pressed in the correct depth. Anyone know?

OEM

Lock ring style

o-ring style

 

just different designs by different manufactures.as far as material,we like the C630 nickle bronze here.before doing your own guides,make sure you have the proper equipment to size them (we prefer honing over reaming) & cut seats when guides are installed