360 Teardown.. Bearing Opinions (dialup beware)

[dbesade]

Okay,

Hows these bearings look



#1 Main:


#2 Main:


#3 Main:


#4 Main:


#5 Main:


#3 looks pretty groovy.. I wasn't told the milage on the 360 when I got it, however it came from an 80's J truck but what is weird is the casting numbers on the block are from a 76.. which means this engine was probably swapped in. Opinions are welcomed.. I'm good at this tearing down part.. its the putting back together than makes me nervous

-Dave

[Blown7]

Yep they look like old bearings, don't worry about them at this point. It's what the crankshaft looks like and measures out that counts. Is there any fretting on the main caps?

Jeff

[82Waggy]

Interesting that #3 is worn into the copper so evenly and none of the others are. It was probably too tight when installed but I would also check for blockage in the main bearing oil feed path to #3.

Looks like the engine had its' share of dirt in the oil.

Even wear pattern suggests the crank bore is straight enough - no align hone will likely be necessary.

Like Blown7 said, mic the crank and have it turned as necessary to clean it up - install the correct size new bearings.

[dbesade]

Yep they look like old bearings, don't worry about them at this point. It's what the crankshaft looks like and measures out that counts. Is there any fretting on the main caps?

Jeff

Jeff,

Sorry if I sound n00bish (which is fine because I am ) But what is fretting?

82waggy,

I was wondering about #3 myself.. bearings appear stock.. at least the pistons were stock (had AM script logos on them).. but got all the pistons out of the bores and I'll probably pull the crank out today or tomorrow and finish the tear down. So I can get started on the machine work.

-Dave

[Blown7]

Yep they look like old bearings, don't worry about them at this point. It's what the crankshaft looks like and measures out that counts. Is there any fretting on the main caps?

Jeff

Jeff,

Sorry if I sound n00bish (which is fine because I am ) But what is fretting?


-Dave

Dave,
Fretting is the minute movement of the cap rubbing on the block.It can be identified by a disappearing of the original machining marks. The surface material has a non directional sometimes shiny area. It can be caused by the cap to block mating surfaces not being flat, parallel and square to each other even when the cap is fully torqued. Sometimes if allowed to proceed long enough you'll have the kind of wear pattern you have on the number three thrust bearing. Also if the number three main journal is out of round you'll see that kind of wear pattern. The important part is to have the crankshaft inspected and inspect the block cap area, if all is well, everything else is just the previous history. You'll be writing a new history when it's all overhauled.

Jeff

[AMX69PHATTY]

Might there be an AM logo on the backs of the bearings if stock ?

[dbesade]

Might there be an AM logo on the backs of the bearings if stock ?

There is a script AM Logo like on the pistons on the Main bearings and the Rod Bearings.. followed by "AT-20"

-Dave

[dbesade]

Yep they look like old bearings, don't worry about them at this point. It's what the crankshaft looks like and measures out that counts. Is there any fretting on the main caps?

Jeff

Jeff,

Sorry if I sound n00bish (which is fine because I am ) But what is fretting?


-Dave

Dave,
Fretting is the minute movement of the cap rubbing on the block.It can be identified by a disappearing of the original machining marks. The surface material has a non directional sometimes shiny area. It can be caused by the cap to block mating surfaces not being flat, parallel and square to each other even when the cap is fully torqued. Sometimes if allowed to proceed long enough you'll have the kind of wear pattern you have on the number three thrust bearing. Also if the number three main journal is out of round you'll see that kind of wear pattern. The important part is to have the crankshaft inspected and inspect the block cap area, if all is well, everything else is just the previous history. You'll be writing a new history when it's all overhauled.

Jeff

Jeff,

I didn't see what you are describing on any of the bearings... Looks to be a fairly even wear pattern. But I'm by no means educated on what exactly I'm looking at ;) but its surely a nice site to see some progress on the teardown.. damn thing has been sitting in my living room for too long.

-Dave

[rollen dean montoya]

dave,
make sure you hot tank the block, heads, and the caps.
let them soak for at least 3 days just to make sure that all oil passages are clean.get the crank checked.

[jeepsr4ever]

Other than dirt inclusion it doesnt look like the crank is twisted or you have oblong mains. That last pic almost looks like you lost chunks of coating.