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How tight should my wristpins fit??? #222103 02/12/09 12:53 PM 02/12/09 12:53 PM
Joined: Jan 2003 Posts: 732 M mikemotorhead OP super street
mikemotorhead OP super street M Joined: Jan 2003 Posts: 732	Should they rotate freely in the piston of fit pretty tight?? Thanks Mike

Re: How tight should my wristpins fit??? [Re: mikemotorhead] #222104 02/12/09 01:00 PM 02/12/09 01:00 PM
Joined: Feb 2004 Posts: 3,076 Renton, Wa. C Classof70Chally super gas
Classof70Chally super gas C Joined: Feb 2004 Posts: 3,076 Renton, Wa.	IMO they should spin freely, even if you are using the press fit in the rod type. I just went thru this with a motor I'm building. I went with Diamond pistons and 440 Source forged rods with a full floating .990 pin. The pins would literally 'fall out' of the pistons but would not go into the small end of the rod without some force. I brought them to my machinist and he said that instead of having about .0005 or .001 clearance fit, they were about .001 interference fit! After he honed the rods they were fine but weren't 'ready to go' out of the box.

Re: How tight should my wristpins fit??? [Re: Classof70Chally] #222105 02/12/09 01:13 PM 02/12/09 01:13 PM
Joined: Mar 2003 Posts: 15,493 the boonies aarcuda I Live Here
aarcuda I Live Here Joined: Mar 2003 Posts: 15,493 the boonies	if you cant spin them when theyre in, theyre too tight

Re: How tight should my wristpins fit??? [Re: mikemotorhead] #222106 02/12/09 01:13 PM 02/12/09 01:13 PM
Joined: Mar 2007 Posts: 12,013 Finally a HUSKER again Moparnut426 I Live Here
Moparnut426 I Live Here Joined: Mar 2007 Posts: 12,013 Finally a HUSKER again	Quote: Should they rotate freely in the piston of fit pretty tight?? Thanks Mike I have said it before on here, and most agree. NOTHING should be trusted out of the box. It should be your responsibility to test fit everything, and you are correct for asking. They should fall right out. I accually took a set of press fit mopar small block rods and for a project reamed out the small end, burnished in a bushing, and honed them to fit and the spec was .005. I just spent a crap load of cash on a rotating assy with known good parts from a VERY reputable guy (DRAM), and I an meticulously checking everything.

Re: How tight should my wristpins fit??? [Re: Moparnut426] #222107 02/12/09 01:47 PM 02/12/09 01:47 PM
Joined: Aug 2003 Posts: 43,308 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,308 Bend,OR USA	Quote: Quote: Should they rotate freely in the piston of fit pretty tight?? Thanks Mike I accually took a set of press fit mopar small block rods and for a project reamed out the small end, burnished in a bushing, and honed them to fit and the spec was .005. Are you sure the clearance you ended up with was five thousands (.005) and not one one half of a thousand, .0005. If it is .005 you need to fix that now I like .0008 to .001 on a drag motor that will be RPM when the motor and oil are not hot Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: How tight should my wristpins fit??? [Re: Cab_Burge] #222108 02/12/09 02:23 PM 02/12/09 02:23 PM
Joined: Mar 2003 Posts: 15,493 the boonies aarcuda I Live Here
aarcuda I Live Here Joined: Mar 2003 Posts: 15,493 the boonies	Quote: Quote: Quote: Should they rotate freely in the piston of fit pretty tight?? Thanks Mike I accually took a set of press fit mopar small block rods and for a project reamed out the small end, burnished in a bushing, and honed them to fit and the spec was .005. Are you sure the clearance you ended up with was five thousands (.005) and not one one half of a thousand, .0005. If it is .005 you need to fix that now I like .0008 to .001 on a drag motor that will be RPM when the motor and oil are not hot .005 is WAAAAAAAAAY loose. somethings gunna blow

Re: How tight should my wristpins fit??? [Re: aarcuda] #222109 02/12/09 03:14 PM 02/12/09 03:14 PM
Joined: Mar 2007 Posts: 12,013 Finally a HUSKER again Moparnut426 I Live Here
Moparnut426 I Live Here Joined: Mar 2007 Posts: 12,013 Finally a HUSKER again	Yep, i had a typ 0. I forgot a zero. .0005 is what I was suposed to type, sometimes my brain and fingers dont agree. u guys are sharp!!

Re: How tight should my wristpins fit??? [Re: Moparnut426] #222110 02/12/09 05:16 PM 02/12/09 05:16 PM
Joined: Dec 2005 Posts: 293 Kansas City Metro M mbogina enthusiast
mbogina enthusiast M Joined: Dec 2005 Posts: 293 Kansas City Metro	General spec on pin fit in the piston is .0003 to .0005.pin fit in a floating pin rod is generally .0005 to .0007. Be a Rebel- Break the Laws of Physics!

Re: How tight should my wristpins fit??? [Re: mikemotorhead] #222111 02/12/09 05:37 PM 02/12/09 05:37 PM
Joined: Nov 2008 Posts: 671 Wisconsin USA B Bill MeLater mopar
Bill MeLater mopar B Joined: Nov 2008 Posts: 671 Wisconsin USA	I just had one speedpro 2355 out of a set of 8 that was .009 out of round in the pin bore(Yes 9 thou believe it or not). This was on a USA made set. Had to replace it with a Made in China piston. The quality of the chinese part was pretty crude compared to the USA piston but the pin fit was correct..Got a new ashtray outta the deal too

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