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Valve guide ID

lr172

Well Known Member
I am going to make a wobble test tool to check the clearance on my IO-320-B1A (original cylinders from the 60's, but overhauled in the 2000 timeframe). From my research, it seems that everyone is using the .4995 reamer for the guides. I am wondering how consistent the Valve stem / guide dimensions are across different lyc variants.

I was hoping to get a valve stem dimension and make the tool before pulling the cowl and valve spring. Does anyone have a good reference for determining valve stem dia for different engines? I see reamed dimensions of .499, .500, and .501" I am guessing that the valve stems must be sized for the clearance with the guide sized for .500". Also guessing that the different reamed sizes were to account for variances in the actual valve stem diameter.

Appreciate any guidance here.

EDIT: Ok, I see the OH manual lists .494" as the only valve OD, assuming 1/2" stems. Still wondering why they have three different reaming possibilities in the SB. Guessing that if my stems measure 494 that I should use the 4995-5005 reamer.


Thanks,

Larry
 
Last edited:
from McFarlane

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