Exhaust valve guide clearance acceptable?

[blue_tractor_man]

Back working on my 1967 Kohler L600 flathead 4 cylinder engine. I bought it all new valves because the old exhaust valves were trashed and the old intake valves had rust and pitting. The book calls for the valve guides (cast iron) to be .312 - .313. One of the exhaust valve guides is on the upper edge of that, maybe .3135. The exhaust valve will have .005 clearance, and the book calls for .0025 - .004. So, it is about .001 - .0015 over spec. If it makes any difference, the engine has tappets that push directly up on the valve stem, so that there is no side loading whatsoever. It is an 1800 RPM engine, so it runs relatively slow. Also, since it is an exhaust valve, oil consumption and vacuum leaks won't be a problem. My guess is that in short order, soot will coat the inside of the guide and tighten it up a little. The guide is still available for $20 if the YT brain trust thinks I should replace it. I don't really want to replace that guide if I can avoid it. What do y'all think?

 

[Janicholson]

If it is a sometimes toy, leave it, if you intend to use it for 3 to 300 hrs a year, I would replace it. Jim

 

[Janicholson]

I meant to key in 200 to 300 hrs or more/year. Jim

 

[oldproudvet]

Knurl it or bronze wall it. Simple. Just be sure you've got enough clearance, as you said L heads have iffy guide oiling.......

 

[rustred]

.003 is a nice happy place to be. the thing is once guides get worn it causes the valve seat to wear and pound out because the valve stem can wobble. but with .001 wear its not a big deal yet. also carbon on the stem causes wear. you don't want carbon on anything.

 

[JWA]

I'd run it.

 

[dr sportster]

I would run it too. Exhaust valves expand a lot in the guides and without clearance will always seize. Or as they say better to hear them than smell them !

 

[blue_tractor_man]

Survey says......"Run it!" I will let you guys know how it goes.