Posted by Matt Wilson [108.162.221.77] on Monday, February 11, 2019 at 19:09:56 :
In Reply to: Connecting Rod Bushings posted by Matt Wilson [108.162.221.77] on Sunday, February 10, 2019 at 21:45:00 :
Well, I think I found why my machinist is having a hard time coming up with the correct interference fit for the bushing into the rod bore diameter. I managed to find an online copy of the 2006 AERA connecting rod manual, and for many engines, it provides the inner diameter of the rod, which the bushing presses into, but not for any of our flatheads.
He's going to have to measure the bores of a couple other rods and see how those diameters compare to the OD of the standard size bushing and derive the amount of press fit based on that. The only problem is that we don't know ehat bushings came out if these rods. It seems they ould be bushings with either the 0.9135 OD or the bushings with the 0.915 OD.
I measured a couple 251 rods the other night and got bore IDs ranging from 0.9135 to 0.9142. If they had 0.9135 OD bushings in them, then there's no press fit unless those bushings were burnished to expand to fit the rod. If they had the 0.915 OD bushings in them, that would provide about 0.001 - 0.0015 press fit and maybe no burnishing required?
I even tried calling Sealed Power (actually Federal Mogul), and they told me the press fit should be 0.004 - 0.0045, which seems way too much.
I'll call VPW tomorrow to see if they have a spare 265 rod, but considering that they are rare, I may be stuck finding a solution with the rods I have now.
At least I am starting to understand why my machinist is struggling with this.
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