GrahamPaige29

Graham Paige Connecting Rod/Bearing Clearance?

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Hello again.  I removed the pistons/connecting rods from my 1929 Graham Paige model 612 to hone the cylinders and install new rings.  The bearings look excellent, but when I was removing the connecting rod caps, some of the metal shims were destroyed accidentally.  These were very thin.  I'd say about as thick as two sheets of tin foil.  When I'm ready to reinstall my pistons and rods, I'd like to leave the "correct" gap between the babbit bearings and rods.  Trouble is, I don't know what that is.  I could use plastigauge or borrowed tools to check inner and outer diameters, but I'm not sure clearance what I'm aiming for.  Too little clearance, and the bearings will burn.  Too much and the oil pressure will be bad and the rods will clunk.  They always say "check your car's recommended settings" but in this case I don't have them.  Any guesses?

IMG_2432.JPG

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1 hour ago, JFranklin said:

Aim for .0015 clearance or so.

That's about what I thought.  It's not like this car will be a hot rod.  I'm guessing that because some wear will have occurred since the last removal of the caps, I might not need to replace the ultra-thin shims.   Thanks.

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Spinneyhill    250
8 minutes ago, GrahamPaige29 said:

Any guess on the torque on the cap bolts? 

Use the diameter and thread count to enter a generic chart of tightening torques for Grade 2 bolts.

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3 minutes ago, Spinneyhill said:

Use the diameter and thread count to enter a generic chart of tightening torques for Grade 2 bolts.

Thanks.  I don't really like the "castle" bolts with the cotter pins that are on there now.  Is there a better alternative that is more tune-able?

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1 minute ago, Spinneyhill said:

"Tune-able" = ?

It seems like after you tighten them, the castle nuts sometimes stop in a position that doesn't allow the insertion of the pin.  Maybe I'm just over thinking this (again!).

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Spinneyhill    250

I have always just tightened to the next hole, based on what I believe I have read in shop manuals.

 

Torque figures generally weren't published at that time and mechanics just did it "tight enough". They didn't have thread lock chemicals then either so they used split pins.

Edited by Spinneyhill (see edit history)

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1 minute ago, Spinneyhill said:

I have always just tightened to the next hole, based on what I believe I have read in shop manuals.

Yeah.  It should be ok.  I'm just a rank amateur who's over worried.  Thanks.

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Spinneyhill    250

threads on bolt and nut should be clean and dry (or clean and oiled, but use the appropriate value from the chart). But do not use a tap or die nut on them, the torque figures will not apply.

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Larry Schramm    874

And USE THE CASTLE NUTS along with a cotter key to keep them from coming loose.  In the old days they also used wire to keep the nuts from turning.  Think aircraft type of work.

 

Here is an example.

 

https://www.google.com/search?q=aircraft+nut+wiring&source=lnms&tbm=isch&sa=X&ved=0ahUKEwinqsaUlOnTAhUn34MKHahJBn4Q_AUIBygC&biw=1093&bih=490#imgrc=vUWX8jliQGFStM:&spf=1494550962030

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Tinindian    321

I was taught that failing definite information the clearance should be ,001" per inch diameter of the journal.

I have always removed the nut and filed it so that when proper torque was reached the slot lined up.  A Packard mechanic told me this was the correct way.  I don't know if it is correct or not but it has never failed me.

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Larry Schramm    874

I had a chart some time ago but can not find it I seem to remember that clearance should be about .001"/ inch of journal diameter.

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Spinneyhill    250

When you file the nut, are you sure you are making the new surface perpendicular to the axis of the thread? If that surface is not perpendicular, you will be bending the bolt every so slightly and your torque will not put the tension into the bolt it is expected to.

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Stude17    12
On ‎12‎/‎05‎/‎2017 at 3:40 PM, Tinindian said:

I was taught that failing definite information the clearance should be ,001" per inch diameter of the journal.

I have always removed the nut and filed it so that when proper torque was reached the slot lined up.  A Packard mechanic told me this was the correct way.  I don't know if it is correct or not but it has never failed me.

I agree with you Tinindian over tightening to the next slot is not the way to go. I generally rub the face of the nut on a flat file and in some cases where the nut is hardened I might use fine emery tape or paper.  Generally the amount of material to be removed is minimal.

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