Re: [AMC-list] MOTOR WENT BYE BYE!!!!

[Frank Swygert <farna@xxxxxxx>]

The only time I've seen that issue is when I got in a hurry and installed all the rod caps backwards. Hard to imagine doing that, but I pulled them all off and placed them in the correct order with the "bump" facing the right direction, put the pistons in, then put the rod caps on. 

When running dual carbs I had one with the wrong size jet and burned a hole in a piston. Noticed the worn down bearing when pulling that piston. Engine only had 10-15K on it! Pulled another rod bearing, same thing. Pulled a main, and it looked nearly new. Inspected the rods and caps closely. The machine shop had put the rods on the pistons backwards! In the 196 the piston only goes in one way, notch forward, dome offset to the left. The rods have one oil squirt hole, and have a "bump" on one side, indicating the front. The shop was supposed to have a short block ready for me months before I just went over and picked it up IN PARTS. So I had to assemble the engine quickly and didn't check the rods at all. I didn't notice that the stamped numbers were on opposite sides of the rod and cap either. 

Talked to a local machine shop and we decided that the oil squirt hole really wasn't a problem. AMC put it to one side so that a little extra oil went on the cam instead of the side of the block. It isn't necessary for the cam, but if you're quirting oil around it may as well be put to use. The rods were resized so the caps fit as installed on all of them (yep, had to pull them ALL out!) as they didn't want to press the pins out of the pistons and risk cracking a hard to find piston. 

The rods could be slightly out of round on the big end just from normal use, though it's not common. Could be that they were over or under torqued? you didn't have the crank turned, and you reused the old bearings. Did you take the bearings out of the rod caps and/or block? If so and they were mixed up, that could explain the problem. Replacing with standard bearings will let you run it a while, but the crank really needs to come out and the big ends of all the rods checked or resized to truly fix it. 

-------
Date: 9 Jul 2009 04:25:11 -0000
From: das24rules@xxxxxxxxx

got the oil pan dropped tonight and rods pulled, and pistons popped out. rings
looked good. crank looked good, and rods looked good. #6 rod bearing is almost
completely GONE. very little left. not spun, just worn. wierd. none of the
rods were loose either. real wierd think is, i had pulled the rod caps off
and checked the bearings and crank. everything looked like new. now, all the
bearings look worn pretty bad. all down to the copper or what ever the base
material is. got to clean out the bottom of the oil pan as it has a fair
amount of bearing junk in it. 

anyone else ever have issues with the bearings after they checked them?

--
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
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