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View Full Version : drilling connecting rod small end


83rampage
06-25-2009, 08:24 AM
Just wondering how many guys are doing this? Any problems or things to watch for? From what I gather a 3/32 chamfered hole is the prefered method.
boost geek
06-25-2009, 10:37 PM
My machinist put rather large holes in mine, running a .927 pin.
83rampage
06-25-2009, 11:37 PM
I went ahead and drilled them tonight anyway. Don't think it'll hurt anything. The last engine I put together with floating pins had the top of the rod drilled from factory.
turbovanmanČ
06-26-2009, 03:35 AM
http://www.turbo-mopar.com/forums/showthread.php?t=11890&highlight=drill
mopar-tech
06-26-2009, 05:07 AM
Just wondering how many guys are doing this? Any problems or things to watch for? From what I gather a 3/32 chamfered hole is the prefered method.

Just weakens the rod for no real gain.
83rampage
06-26-2009, 09:18 PM
Just weakens the rod for no real gain.

I tend to disagree. I think any extra lubrication to the pin is beneficial. Most of the mopar engines I've taken apart with full floating pins always seem to have varying degrees of pin discoloration.

As for the strength, I don't think it will weaken it to the point it would ever break on the small end. Have yet to see one break there.

The beam is always the weak link.
mopar-tech
06-27-2009, 06:25 AM
I tend to disagree.

I have never seen a 2.2/2.5 *floating pin* worn out or discolored.
cordes
06-27-2009, 09:33 AM
I have never seen a 2.2/2.5 *floating pin* worn out or discolored.

I've seen them discolored, but not due to heat, just from the nice oil patina that covers everything in a really well used engine.
83rampage
06-27-2009, 12:54 PM
I had a set of pins just this week that were blue and seemed to be lacking lubrication. Had I not already polished them I would have taken a picture. They polished up fine.

The pins don't wear, the bushings do.

Sorry I still don't see your point. It took me about 20 minutes to drill the rods. Maybe it will do nothing, but it may help, and as far as strength goes, I still think if the rod ever fails, it won't be because of a 3/32 hole in the top.

I just finished rebuilding a 2.4L GM with full floating pins. GM took the time to drill the tops of the rods...for no benefit? Can't see an automaker doing anything they don't need to. The pins in that engine had no discoloration whatsoever.
crazymadbastard
06-27-2009, 01:16 PM
Those pins are pretty tight on there and seem more like press-in whenever I had to mess with them. So more lube could help, or since they are tight maybe it won't.