Rod bearings

RoyLuke

Well-known member
Apr 18, 2007
200
5
Trying to fit this engine is uphill all the way.
I put in two pistons tonight and as soon as I torqued the Rods to the crankshaft the engine was locked tight.
I got two sets of bad main bearings before one that worked. It looks like the same for the Rod Bearings. I suspect they are not the right thickness.
Should I try to step-torque the bearings whilst turning the crankshaft?
 

ERover82

Well-known member
Nov 26, 2011
3,623
277
Darien Gap
Did you replace the crankshaft? If not, the bearings were either made out-of-spec or you ordered oversized bearings on accident. What's the part # on the bearings you got?
 

pdogg

Well-known member
Jul 18, 2005
1,206
24
Phoenix, AZ
it would make no sense that they'd be too tight would it? I assume you have assembly oil in there too? mine went in smooth as silk and turned easily after install..
 

ERover82

Well-known member
Nov 26, 2011
3,623
277
Darien Gap
it would make no sense that they'd be too tight would it? I assume you have assembly oil in there too? mine went in smooth as silk and turned easily after install..

He may have installed 10 thou (or more) over bearings intended for a reground shaft. That or if he replaced the shaft with an aftermarket part, it may have been ground incorrectly.
 

pdogg

Well-known member
Jul 18, 2005
1,206
24
Phoenix, AZ
He may have installed 10 thou (or more) over bearings intended for a reground shaft. That or if he replaced the shaft with an aftermarket part, it may have been ground incorrectly.
ok thinking about it again, yeah totally makes sense.. I was reversing that logic in my head..
 

terryjm1

Well-known member
Jan 23, 2011
682
114
Trying to fit this engine is uphill all the way.
I put in two pistons tonight and as soon as I torqued the Rods to the crankshaft the engine was locked tight.
I got two sets of bad main bearings before one that worked. It looks like the same for the Rod Bearings. I suspect they are not the right thickness.
Should I try to step-torque the bearings whilst turning the crankshaft?
Remind me who/where you are getting your parts so I know to not buy there.
 
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mearstrae

Well-known member
Mar 15, 2017
118
11
Pennsylvania
The bearings should be marked if they are over size, stamped ".010", etc. Use Plasti-gauge (available at parts stores) to check bearing clearance on all bearings, mains included. This gauge is just a string of wax that you compress by torquing caps to spec, removing, and then checking the sqished wax with the scale on the side of the package, and shoot for about .002" clearance. If you have access to inside and outside micrometers that would be even better. Oh, and piston rings also need to be checked for clearance, so they don't bind up when hot, this is done by putting them square in the bores one by one and checking the ring end gap with a feeler gauge. Not sure of the right ring gap maybe about .015", check a rebuild manual for exact bearing and ring clearance specs.
 

WaltNYC

Well-known member
Mar 3, 2010
585
65
NYC
In case you need it the overhaul manual is in engine section of the google drive.