Chevy 283 Main Bearing Caps

I picked up a 1966 283 as a project to teach my grandsons how and engine works and what goes into an engine. As we were tearing it down we noticed some unusual wear in the main bearings. The engine had beed rebuilt at some point and I'm thinking they got the main bearing caps out of order. Each main bearing cap has a part number. Now my question, can anyone tell me the order of the main bearing caps by part number? Or are the number meaningless?
Thanks in advance for you help,
Wally

 

The rear can only be the rear. The rest as I recall all have a single digit number on then ie 1 thru 4. 1 is the front,also remember the little notches that locate the bearing shells need to be on the same side. I've seen more than one engine with the main or rod caps installed wrong.

 

The #s you are seeing on the caps are only casting #s and have no reference to the order that they were placed on the block. It was the job of the first cat to tear down the engine to mark the caps in placement of how they fit on the block. If I was trying to save the block on a budget I would put the caps back on the block with the crank and the bearings removed. Torque the caps down and check at the parting line for a perfect fit as in the cap and block mating surface needs to be perfectly smooth. Once you are satisfied with the fit of all of the caps get a new set of bearings and install them along with the crank,torque everything down and the crank should spin freely. Now if this fails it's the 4 card monty switcheroo game until you find the right placement !! There will be 16 wrong combinations and 4 correct ones. Good Luck >>>>.

 

I had to replace two caps on my 348 as the old ones had been broken,brazed and reinstalled and run for many years (yes it did have a minor knock). We found a couple good replacement caps and I had my engine guy align hone the works to be safe.

 

This I have had to do on a few occasions when some guy brings me a box or a bucket full of parts and tells me he wanted to save me time and tore it down himself. So I ask him if he #erd the caps (main and rod) No, he says, they all interchange don't they. Thanks for saving me some time.

 

i think johnevans may be right , i believe the last 283 i did the main caps were numbered 1-2-3-4..... worth taking a look. i think there was also an arrow pointing forward

 

Hi 52, there should be 1 2 3 4 on the caps and a arrow .....Good luck 52 csb 36 is right///

 

Once I cleaned the caps, I found the numbers. They were installed in the right order according to the numbers. Now I'm back to square one. Some main bearings are worn on the block side and some are worn on the cap side. Any ideas?
Wally

 

you probably already checked this......are the arrows pointing forward? are both bearing tangs on the same side?

 

No arrows, but tangs line up.
Wally

 

That kind of wear is usually a sign of mis-aligned bearing bores. Did you note if the tangs were were both on the same side when you took it apart? If they were I think your next step is to have a machine shop check out the main bering bore alignment.

 

That's what I was afraid of, looks like this could get expensive.
Thanks,
Wally

 

why don't you PM Titus on here....he is an automotive machinist and is right in your area. i'm not sure if he still has the equipment to check your main bores , but worth checking into