360 Breakdown and Inspection w/ Pictures

[1966Coronet]

I tore down the engine replacement for my Coronet. It's a 360/5.9L LA series. The guy that sold it to me told me that he had worked on it. When I took the engine apart, the first sign was the foul "burnt-oil" smell like burnt pop-corn.

When the cam was removed, the bearings where severely damaged. And finally when the Main bearing caps were taken off, I confirmed that the engine's bottom end had not been touched. Main bearings were still stamped with the yr. of the engine (AT-20/75)

The rod bearing are standard, and the rod journals are impeccable. The main journals are another story, to me it looks like the engine might have ran out of oil at some point. The cylinder walls are impeccable as well.
The pistons, are stamped "818" on top and have a casting number "4006817" are this standard? I'm guessing they are.

My question is this.
A) if the rod journals are fine and dont need to be resized, should I still have them turned?

B) The main bearings are oversize .020 over, can this have come like that from factory? And if so, is it ok to take over .030 or does it compromise the integrity of the crank?

C) Trying to stay "low-cost" I would prefer to keep the pistons that are in, and just re-ring them. Is this ok, or should I go over-bore?

D) What are the benefits of over-boring to 0.030 over standard?

I'm posting pictures here hopefully you guys can help me before taking the engine and head to the machine shop. Thanks in advance for your advise.

 

[69Bee]

A) if the rod journals are fine and dont need to be resized, should I still have them turned?

A: Yes. Journals will be out of round, tapered, etc. It is part of the crank grind anyway.

B) The main bearings are oversize .020 over, can this have come like that from factory? And if so, is it ok to take over .030 or does it compromise the integrity of the crank?

A: It could, but the block would be stamped, and the bearings would be dated the same as the rods. It will not compromise the crank to grind it to 0.030".

C) Trying to stay "low-cost" I would prefer to keep the pistons that are in, and just re-ring them. Is this ok, or should I go over-bore?

A: Going "Low Cost" means that you will be doing this again sooner than if you had done it properly in the first place. Bore and hone to 0.030", and put in new pistons. The old bores will be tapered, and out of round, making ring seal marginal at best.

D) What are the benefits of over-boring to 0.030 over standard?

A: Boring and honing the cylinders will produce straight and round cylinder for the new pistons and rings. This will minimise blowby and help with proper ring break-in.

Save the money, and do it right the first time. You will be MUCH happier you did.

 

[Meep-Meep]

I have honed and reringed plenty of engines over the years with great success. This one looks like a well used core but not destroyed. Only by measuring everything carefully, after it's cleaned, will you be able to make a decision on the repair method. You can hone up to about .008" taper in the bore and the crank can be polished if it's not too grooved up. The rods will most likely be out of round so you may have to have them resized, but the rest can usually be saved. The insert I'm looking at has a strange wear pattern so that rod should get looked at carefully or just resized on equipment that holds the rod sides parallel to the big end bore. This is the only way to straighten out a bad rod.

 

[66 coronet]

Your going to be taking the block to a machine shop to get it cleaned and new cam bearings installed , ask around and find a good one they can tell you if it needs to be bored and if the crank needs to be turned.