 Question on Connecting rod modificatiion, Wrist pin issue |
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| finchmunoz |
 Jul 31 2022, 07:23 PM
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#1
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Newbie  Group: Members Posts: 34 Joined: 3-July 11 From: Manila, Philippines Member No.: 13,272 Region Association: None  |
Any engine builder might help me with an advice…
I’m building my 78x96 engine and found an issue with the piston pin… my liner kit came with 24mm pins and the rods are 22mm. Can I have the rods opened up to 24mm? Will it be safe? (I’m using a c55 cam - 7k rpm maximum). The machinist will end up reaming the rods taking out 1mm to allow the pins to fit Your opinions will really help. TIA Attached thumbnail(s)  
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Replies(1 - 5)
| Montreal914 |
Jul 31 2022, 08:11 PM
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#2
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Senior Member Group: Members Posts: 1,588 Joined: 8-August 10 From: Claremont, CA Member No.: 12,023 Region Association: Southern California 
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You will actually need to bore out the connecting rod larger than 24mm since you should have a bushing in there. (IMG:style_emoticons/default/dry.gif) At this point, your rod will have been weaken a lot at the small end.
I would get the right pistons with 22mm wrist pin, such as the Keith Black for stroker. |
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| finchmunoz |
Jul 31 2022, 10:08 PM
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#3
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Newbie Group: Members Posts: 34 Joined: 3-July 11 From: Manila, Philippines Member No.: 13,272 Region Association: None |
QUOTE(Montreal914 @ Jul 31 2022, 06:11 PM)  You will actually need to bore out the connecting rod larger than 24mm since you should have a bushing in there. (IMG:style_emoticons/default/dry.gif) At this point, your rod will have been weaken a lot at the small end. I would get the right pistons with 22mm wrist pin, such as the Keith Black for stroker. PMd you. I’m interested on your KB liners |
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| cgnj |
Aug 1 2022, 01:48 AM
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#4
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Senior Member Group: Members Posts: 627 Joined: 6-March 03 From: Medford, NJ Member No.: 403 Region Association: None
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I have a few questions before I toss my opinion.
Have you test fit your crank, cam & rods in the case? What size are the rod journals? How long are the rods? What is the chamber volume? Assuming that you have no clearance issues, I would use either KB stroker pistons, or JE pistons. There is a big difference in the weight of 22mm pins compared to 24mm. I don't recall the difference, but I weighed both types on an analytical scale. Less rotating = free power. Good Luck with the build. pistons |
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| ChrisFoley |
Aug 1 2022, 04:53 AM
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#5
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I am Tangerine Racing Group: Members Posts: 7,934 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None
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Didn't the machinist tell you altering the rods that way was a bad idea?
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| 930cabman |
Aug 1 2022, 05:40 AM
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#6
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Advanced Member Group: Members Posts: 3,144 Joined: 12-November 20 From: Buffalo Member No.: 24,877 Region Association: North East States
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Find the correct pistons. I would not alter the rod's
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