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Piston Pin Oil Hole


Doug71zt

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I'm modifing stock rods for full-floating pins and was wondering if anyone knew what size the oil hole in the top of the rod should be. I know that it was covered in the how-to Horwitz (sp?) book, but I can't find my copy. I did find the correct bushings from Manley. I just need to press fit, hone and do the oiling hole.

 

Thanks

 

Doug

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I am drilling the top of the rod for oiling, 1/8 inch with a countersunk surface. Manley also recommended 1/8. The recommended press fit for the bushings was .004, but the machinist and I both think that it is too tight a fit for a bushing that brittle/thin. The wall thickness is .045. I was thinking .002 interference fit would work better. The part number at Manley is 42303. The dimensions are:

 

ID - .820

OD - .910

Length - 1.015

 

You may want to be careful with the metal on metal float. There have been a couple guys here that have tried it and ended up with galling on the pin.

 

Thanks for the information

 

Doug

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Hey, thats my picture, of my rods, HEHE. Yea .125" id, with a chamfer for oil collection and stress reliving. Yea DONT run forged steel on wrist pins, its so easy to get a machinist to install and hone bushings to the correct size. Press them in at a 2-3 thou interfernce fit.

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Doug,

Go with the full press fit! I have been installing rod bushings for a long time, please believe me. If it was an extreamly thick bushing, .002 might work. The thin bushings are not brittle, and will press in very easily with high pressure lube. The last thing you need is a bushing coming loose. The best method is to chamfer/polish the leading edge of the rod bore with some 400 emory paper, then do a nice radius on the OD of the entry end of the bushing. Then press them in. Drillthe oil hole, then hone (.0008) for proper pin clearence. many bushings are small on the ID as supplied, and require align boring to within a thou or so of the finished size, then a final hone to size. Then when done, use the 400 paper again on the ID of the finished bushing. This will make assembly easier, and allow the pin to slide in and through the the new bushing with no muss or fuss. I recondition Carrillo, & Pauter rod on a weekly basis, and these have very thin bushings. .004 press min.

Phred

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Hey, thats my picture, of my rods, HEHE. Yea .125" id, with a chamfer for oil collection and stress reliving. Yea DONT run forged steel on wrist pins, its so easy to get a machinist to install and hone bushings to the correct size. Press them in at a 2-3 thou interfernce fit.

 

:icon11: hi there thanks for the photo .

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