Adventures in Flat heads valves

[DavidBarkey]

Todays adventure that started yesterday . Neighbours old Yamaha snow blower won'r start . Yesterday I looked at it for a bit , kept washing down the plug . Could not do compression test due to the lack of threads in spark plug hole . but "he doesn't remember ever having the plug out . Yet the plug is newer and there is no threads left in the head . Don't know how it stayed in . Had to fix the head before could even do a compression or leak down test . Simple flat head engine with a aluminum shim gasket . Pull the head , carb, muff, ect, to fix spark plug threads and check the lash clearance . Cylinder bore looks like new , thats a good sign. The intake seals fluid test but only .002" clearance . The exh doesn't seal and has .020 clearance .
Pull the exh valve and chuck in lathe . Head is bent , suspect missing threads caused this do to the lack of carbon . Parts are NLA , head gasket is reuseable with a little spray sealer . The valve , going to have to straighten it . With valve in the lathe checked run out with dial indicator and piece of steel clamped in the tool post , put pressure on the high spot building each time until close. I worked it from .034 run out down to .003". Then with carbide tool turned the head face concentric again . Now the valve has no clearance , so back in to clip the end to spec. Clip the intake to spec. and lap both in . Reasemble and started on second pull , didn't even need the electric start. .

Not a Case engine , but it is a flat head . Just sharing to show how even with out a valve grinder you can salvage a valve / engine when parts are a problem to get .

[JSinMO]

Glad you got it going. I’ve straightened pushrods before but never tried a valve. It’ll probably run a long time now. That is as long as someone doesn’t cross thread or over tighten the plug again!

[Eugen]

Nicely done Dave! I never thought a bent valve could be straightened.

[DavidBarkey]

Nicely done Dave! I never thought a bent valve could be straightened.

I was not sure either , but when parts are not available and the rest of the engine is in good shape it is worth a try . Just happened to work , so thought I would share as it might help someone else out down the road . Lord now I have learned my share and more on here .