Main Cap Install Direction?

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CaseyW

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Hello,

I am replacing the main bearings in my slant six and I unfortunately don't remember which direction the main cap faces. One side on both the top and bottom bearing has a small protrusion that fits into a little cutout in both the main journal and the main cap. Does the side with the cutout on the bottom bearing, the one in the main cap, go on the same side as the cut-out in the main journal, or are they on opposite sides?
 
All caps, whether main or rod, mate to the "other end" with the bearing tabs on the same end. That is, if you have the block so that looking down at the block with the crank "away" from you, the bearing tabs will be on one side, let's say left. So you put the caps down so that the tabs meet them, also on the left. I hope you realize that main caps must be off the same block, and must be on the correct journals. Same with rods. They are matched at time of manufacture. You cannot switch rod caps from rod - to - rod.
 
67Dart273 said:
All caps, whether main or rod, mate to the "other end" with the bearing tabs on the same end. That is, if you have the block so that looking down at the block with the crank "away" from you, the bearing tabs will be on one side, let's say left. So you put the caps down so that the tabs meet them, also on the left. I hope you realize that main caps must be off the same block, and must be on the correct journals. Same with rods. They are matched at time of manufacture. You cannot switch rod caps from rod - to - rod.
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Thanks for the quick response!
All the rods and rod caps are numbered, and all the main caps as well, and they are from the same engine so I'm in the clear there:)
It just didn't say in my service manual which way the caps went and I didn't want to chance it.
It also says in my service manual that the #1 top main bearing should be chamfered so as to oil the timing chain, but all the bearings except the #3 are the same. None of them are chamfered. Any idea about that?
 
CaseyW said:
It also says in my service manual that the #1 top main bearing should be chamfered so as to oil the timing chain, but all the bearings except the #3 are the same. None of them are chamfered. Any idea about that?
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The factory #1 main top was chamfered, as were aftermarket bearings made years ago. But any aftermarket bearings bought today does not have the chamfer. I take a small file and put a chamfer on the edge of the bearing, myself. It does not need a lot.
FYI, all the main bearings,except #3 thrust, are interchangable with each other, so just pick one bearing and file a small chamfer on the edge. The factory #1 bearing that had the chamfer did have a different part number then #2 and #4. It also had a paint mark on the edge.
 
Charrlie_S said:
The factory #1 main top was chamfered, as were aftermarket bearings made years ago.
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Thanks for the info!

So which part of the bearing is chamfered and how much? Is it the side facing the crank, or the side facing the journal? And is it a small section, or is it along the whole bearing?

Thanks.
 
CaseyW said:
Thanks for the info!

So which part of the bearing is chamfered and how much? Is it the side facing the crank, or the side facing the journal? And is it a small section, or is it along the whole bearing?

Thanks.
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It is he side facing the crank. The factory had the chamfer the whole width of the bearing. I just do the front half, of the shell, from the oil groove toward the chain. I really never measured the chamfer, I just do it by eye. Iwould guess about .015 wide.
 
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