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chris_spring
Senior Member
Username: chris_spring
Post Number: 237
Registered: 02-2019
| | Posted on Saturday, December 31, 2022 - 02:39 pm: | 
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I am familiar with piston aero engines were the wrist pin may have aluminum caps. And I'm familiar with small 2 stroke engines where the wrist pin is retained by clips. Am I correct in saying that the wrist pin on an engine such as the Kingfisher A2 (Waterman) must be pressed out?
Before I apply brute force and ignorance i wish to be sure that pressing out this wrist pin is correct.
I am aware that modern automotive engines sometimes have the con rod heated before the wrist pin is installed so that after cooling the wrist pin is held in place by the con rod.
I believe I am looking at a case where the piston was heated, the wrist pin installed, and as the piston cooled it held the wrist pin securely with the only rotation being between it and the con rod.
I am in the process of making a jig to hold the piston securely while I remove the wrist pin. If my theory on how all of this works is correct, do I need to heat the piston before attempting to remove the wrist pin?
I am checking with you to be absolutely sure I have this correct.
For those of you wondering why I would be taking this apart in the first place is that there is excessive play at the top end. Disassembly has shown that the babbitt on the bottom end is nearly gone. I can only surmise the same holds true for the top end and there is only one way to find out.
And if I get it apart, our next conversation will be about re-babbitting.
Cheers! |
danth48
Member
Username: danth48
Post Number: 11
Registered: 07-2007
| | Posted on Saturday, December 31, 2022 - 05:29 pm: |
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Sometimes the wrist pin is stepped: be sure to push the wrist pin out from the small end. Also there's usually a set screw on the inside |
chris_spring
Senior Member
Username: chris_spring
Post Number: 238
Registered: 02-2019
| | Posted on Saturday, December 31, 2022 - 08:09 pm: |
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Danth48. Thx. Adams has a set screw. This one does not.
Cheers! |
chris_spring
Senior Member
Username: chris_spring
Post Number: 239
Registered: 02-2019
| | Posted on Sunday, January 01, 2023 - 02:29 pm: |
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This morning I pressed out the wrist pin using the jig I made. What was interesting were the two bands you can see on the pin. The pin was installed then given a few healthy whacks with a punch to ensure it didn't go anywhere. There is no doubt about it. Those are punch marks.
For my next trick, rather than tackling it myself I will go on the hunt for someone to re-babbitt the con rod big end. As you can see the babbitt is nearly gone from the cap.
Re-babbitting would be the most correct repair, and would certainly outlive me. I realise it won't come cheap. If any of you have a lead on where I could send it, please sing out.
Happy New Year.
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