WheelhorseBob 1,548 #1 Posted July 17, 2021 Ok Kohler experts, I got my block back bored .020 over. The machine shop ground the valves and said the guides were good. I can’t reassemble yet as I’m waiting on a new governor gear so I was inspecting. I noticed the exhaust guide is not smooth inside like the intake. It almost looks threaded. However it isn’t 5/16 or 3/8. Do the exhaust guides have serrations in them from the factory? Excuse my ignorance on this but at first look I assumed someone threaded it to pull it out. But if that were the case a common size would fit and it does not. Are the serrations to help prevent the exhaust valve from sticking? Took a pic. Share this post Link to post Share on other sites
ebinmaine 62,961 #2 Posted July 17, 2021 Some info here: "What is Knurling valve guides? - Yesterday's Tractors" https://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=farmall&th=511579 Share this post Link to post Share on other sites
WheelhorseBob 1,548 #3 Posted July 17, 2021 1 hour ago, ebinmaine said: Some info here: "What is Knurling valve guides? - Yesterday's Tractors" https://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=farmall&th=511579 Thanks for that Eric. So the exhaust guide is knurled. Sounds like it could be a repair or factory. I’m thinking factory because I bought this engine from the original owner. It had thrown a rod and he installed a new piston/rod/crank. Story goes it was burning oil after he put it together so he tore it apart again and had plans to bore it. Hence the .010 piston that came with it. Well he never got to it. I doubt he would have had the guide knurled and not bored the obviously out of spec cylinder but maybe. Btw it took .020 to clean up the cylinder so I’m sure it smoked with a std. piston. 1 Share this post Link to post Share on other sites
lynnmor 6,762 #4 Posted July 17, 2021 Since your machine shop needed to insert an arbor in the valve guide, maybe he got carried away with a reamer. Share this post Link to post Share on other sites
WheelhorseBob 1,548 #5 Posted July 18, 2021 8 hours ago, lynnmor said: Since your machine shop needed to insert an arbor in the valve guide, maybe he got carried away with a reamer. Maybe but doubtful. Very reputable shop who’s been in business 30+ years. Share this post Link to post Share on other sites
Crazyredhorse 295 #6 Posted July 18, 2021 (edited) Edited July 18, 2021 by Crazyredhorse my harley has them too 1 Share this post Link to post Share on other sites
richmondred01 2,202 #8 Posted July 22, 2021 With cam and tappets out, knock out the old guide, knock in the the new one and ream 5/16. Guides need to be knocked out not pressed. Share this post Link to post Share on other sites