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Working on my rebuilding the engine on my '69 Trophy 500 project and just pulled the pistons off the rods. Made a press tool to center and align to the wrist pins and pressed them out fairly easily. One was tight in the piston and the other was tight in the rod, both looked like they had seen some hard miles but came out smoothly with a little press motivation! Rods looked really good but one surprise, no wrist pin bushings. I had already purchased replacements and I assumed I would press out the old ones, press in the new and ream to exact size.

Do I need to have them opened up at a proper machine shop have them press bushings in and size to the new pins?

Can I pin-gauge them as they are and if OK go with them as they are with no bushing?

Can I ream them myself to press fit the bushings and size? If so what should the interference be for the bushing fir in the rod?

AND THE BIG QUESTION - When all said and done, what should the small end measure out to to be in spec?!?

Thanks and sorry for all the questions!
Brad
 

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I pushed the old bushes out using the new ones.
The new ones needed reaming with a hand reamer until the gudgeon (wrist) pins could be pressed in using my thumbs.
Hope this helps.

 

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If I were rebuilding an old Meriden Triumph, I would instal needle bearing at both ends. You'll pick up some free HP.
 

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The idea is that when the small-end is worn,the rod is suspect.It's probably seen enough use to become a victim of metal fatigue.Enlarging the small-end eye to fit a bush would only weaken it further.

Ideal fit is 0.0005"-0.0012",new.A little more,0.002" or so clearance,would be OK.Try the fit with a new pin.
 

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Small end rod bushing honing really should be done with the rods out of the engine with the proper machine to maintain alignment. It runs about $10 a rod at most machine shops. A lot of the new aftermarket rod bushings also have too large an OD and need to be turned before pressing in.

I would bet home garage rod bushing installation is responsible for more then a few premature piston/ring/bore replacements.'

Rod bushings wear about the same rate as lower end components, so there really isn't any point in performing this operation with an assembled lower end.
 
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