Hot Rod Forum banner

Photos of Main Bearings

12K views 50 replies 13 participants last post by  ChevroletSS 
#1 ·
Hey guys I started taking my 350 roller apart and wanted to get your alls opinion on these main bearings. Do they look normal for having 150,000 miles on them?? Why do they get copper colored??
 

Attachments

See less See more
5
#2 ·
Simple explanation:
The very soft material coating that looks silver is very soft babbit material if the crank makes any friction at all it will give some protection for the crank from damage! your bearings look good for that many miles! You should still at least straight edge the block and check to see if you may need a line bore, and mike your crank and assemble main caps and mike everything!

Jester
 
#3 ·
The copper color is the copper/lead alloy bonding metal between the SAE 1010 steel backing and the lead/tin overlay. The last layer is a flash layer of tin that is used as a dry lubricant. The flash layer of tin is polished off with Scotch Bright by some engine builders before assembly. I have always polished it off and used a good assembly lubricant such as Sealed Power 55-400 or Lubriplate 105 assembly lube.

That is the normal appearance for so-called tri-metal bearings with 100,000 miles on them.
 
#4 · (Edited)
I rub off the cosmetic tin flash overlay to expose the lead/tin layer. The flash overlay is an electroplated layer of tin on new bearings that only serves as a dry lubricant during assembly. Some bearing manufacturers calls it a "sliding layer" on their tri-metal bearings. Instead of using Scotch Bright, you can also dip the bearings in lacquer thinner and wipe them with a micro-fiber towel.
 
#5 ·
Mouse fink:thumbup: How old are you? If your a woman don't tell me LOL.
We old farts called it a "slide coat" And if we needed a .001 or .002 we would use a bearing scraper (if needed) and then emery and Crocas cloth them so all bearing inserts had the same crank clearance!!!! Its funny you knew that:mwink: not too many people do it any more and I haven't heard "Slide Layer" in many years!

Years ago blueprinting was more precise maybe because of better machining today? I try to set all my clearances precise.I don't like .001" on one and variations on the rest The crank never touches the inserts during running conditions anyway the oil pressure holds the crank off the inserts and centers it. like you said its a dry lube for inserting and removing the crank dry when miking and crank rotation dry during assembly. But some people think the crank rides right on the inserts LOL. On good blue prints you may assemble and disassemble many times while measuring and setting clearances and you don't want oil and sticky lubes on everything.

You made a really good post:thumbup:

Jester
 
#6 ·
H compton:

Even when left for a while the older oils with zink provided a layer of protection because the zinc is a high pressure lubricant that adheres to the metals like crank and bearing material its too bad its been taken out of most oils now! But the new lubricant additives must give good protection (except for the cam).

Jester
 
This post has been deleted
#7 · (Edited)
The first and rear main bearings look excellent!

Someone mentioned zddp being taken out of the newer oils, so true, watch out for that. Supposedly they are taking the zddp out to save catylitic converters and energy conservation efforts.

Just for some quick info on that, I recently messaged castrol's "expert" chat, and they said that the Castrol Edge 5W-50 (formulated for classic cars) has 1800ppm of zddp! I did not ask about the phosphorous levels though. For some reason I never thought about the zddp levels protecting the mains.

I am assuming that you pulled the main bearings off since your going to put some fresh ones in, that is an excellent idea.
 
#8 ·
The zinc adheres to metal and is a barrier and protects against high pressure wear, Like timing chains & gears, valve stems , wrist pins, ring pressure on cylinders, crank journals, cam lobes, lifters, push rods, rocker arms, Etc. Any metal to metal contact!

New engines don't need as much, they have less metal to metal contact, Belts instead of chains, roller cams, etc.

Jester:thumbup:
 
#12 ·
Just wanted to say thanks for the info and help guys. This is off the subject but can anyone recomend any piston rings. Im looking for standard size as I am not getting this block machined at all. This is my do it myself project and the cylinder walls are in great shape. Just gonna use a flex hone brush to freshin them up and to debur the block. And its a chevy 350 if noone got that.

Thanks again for the help. Much appreciated:thumbup:
 
#15 ·
Caution:

This is off the subject but can anyone recomend any piston rings. Im looking for standard size as I am not getting this block machined at all.
Pa-Leeze, before you use a piston ring part number that might not be correct, you need to determine if you have a piston w/a deep or shallow oil ring groove.

Up to 1985 the oil rings were deep (0.195" or thereabouts). From about 1986 to about '95 the shallow rings (around 0.165") were used- but there could still be deep groove pistons being used as well.

If you were to use a "normal" oil ring in a shallow groove piston, the piston and ring could be damaged by trying to install the piston into the bore. If you were somehow able to get the piston to go into the cylinder, the engine would be instantly ruined if you cranked it. Not that you're likely to be able to get the piston into the bore in the first place, but stranger things have happened.

Using a shallow ring in a deep groove will work OK but is a hassle to keep the rings in the grooves w/o popping back out.

And if that wasn't enough, there were metric rings (2mm x 1.5mm x 4mm) used from about 1992 to 2002 when the Vortec bowed out. If you had access to the vehicle VIN, the metric ring engines are VIN P.

More on this here.
 
#13 ·
If there is a ridge at the top of a cylinder it will probably break your top ring! If you have a not the best looking bore "Cast" file gap rings are more forgiving then chrome, steel molly, or cast molly! I like Hastings, give em a call! make sure what ever ring you choose use a hone stone in the right grit for that particular ring! And don't use a ball hone! If I was you I would micrometer your cylinders to see how the bore is. or take it to a machine shop for a bore measurement and machine hone!

Jester:thumbup:
 
#14 ·
I've torn down engines with more miles than that and they didn't show any copper. Usually when the bearings hit copper it indicates a good bit of wear.
What I find odd with the picture is the number 1 and 5 bearings look good, which is mysterious to why. The number 1 main bearing is the furthest away from the oil pump and it's the last one to get any oil, yet it's not showing copper. Usually, the number 1 bearing is the first to show copper for that very reason. I think I would have the crank checked over, as when 1 and 5 bearings look good but the 3 center show copper, it indicates a problem.
If you plan to use the block and crank again I would check the clearances very carefully.
 
#16 ·
Main-rod bearings



When ever you see brass on bearings like that means they are worn out and the zinc coating is gone. I am very old school, term, worn to the brass means done for the day,You need to check your cranshaft, road beaing caps, If the carnkshaft is out of round you'll need to get it fixed by a good machine shop along with the connecting rods. Youll need to plastic gauge all the beaings to do the job properly.Anyone who says those are ok berings don't get it.:spank: :spank:When the dude said he took off the outter coating on the bearings just made them lose and will sooner than later cause damage. Good luck and watch what people put on sites.Check and double check information.Master Tech. Ron:welcome:
 
#19 · (Edited)
.Anyone who says those are ok berings don't get it.
I think what was being inferred was YES, the bearings are worn, but worn in a more or less normal manner. Not that these bearings and crank were OK to be put back into service.

Anyway, it is customary practice where I come from to measure the crank and check the saddles and go from there. Resizing the rods should be a given, considering the stock rod hardware should be replaced w/ARP.

IMO the crank need turned, that can be seen from the photo. So new bearings are a given. Whether the saddles check out or not remains to be seen. It wouldn't surprise me if the crank bore needed honing. I seriously doubt it needs bored first.

Jester: ALL I use plastigage for is as a check just to be sure things still look OK before final assembly. It is not accurate enough to use in place of actual measurement tools. I hadn't seen that article before- makes you wonder! But if it's going to be wrong, it will always show less clearance, not more. This happens when the crank gets turned a little or the rod big end gets pushed down against the crank w/the plastigage in place, flattening it more than it should be.
 
#20 · (Edited)
QUOTE Hcompton:
"To jester: have your rods sized to the proper fit and you wont need to do crazy stuff to make your builds work. With the crank properly polished and the rods properly sized your bearings should be drop in if you buy quaility products. Use clevlite bearings and you can just drop them in place and check them with the plastiguage and they will be right over the life of the engine if they are replaced before the bearings fail and takeout the crank."


I couldn't post this earlier my post was sent by mistake:pain:


#1,2,3&4 are bellow the line! That pertain to these:

#1)You already stated you don't measure wall thickness because they are perfect! But some may be interested! and I don't say not to use plastigage! I have it and sometimes use it on final assembly! its a good tool I didn't mean it was only for a backyard mechanic (I re read it and it could be mistaken for that) I had no time to proof read!!!



#2) Some bearings need a little extra clearance then the books say! #3!! How do you set the additional clearance If your already at its max? or if you set it, it will be over max?? Or don't you set it you take it for granted (their perfect) and plastigage is too

#3 I also check bearing crush!! If you just drop em in How do you know? Have you ever seen a Bearing gauge block ?????:confused::drunk: But then again they are perfect out of the box!!!!


#4) The clearances I look for not in your repair manuals
----------------------------------------------------------------------------


#1) Measuring Wall Thickness of Main and Rod Bearings If any ones interested.


Although the best method to measure clearance between the crankshaft and crankshaft bearings is by using a bore gauge while the bearing is installed in the cylinder block or connecting rod, the question of measuring wall thickness of the bearings to calculate the clearances.To measure the wall thickness of a main or rod bearing correctly the location on the bearing that you measure and the tool you use will determine the level of accuracy of the measurement. A micrometer with a ball anvil must be used to fit the curvature of the bearing I.D.

Micrometers with pointed or blade anvils and dial calipers should not be used as they can give false readings and damage the bearing surface. Obviously using an accurate, recently calibrated micrometer is a must for reliable measurement.

Just as important as using the correct tool is the location on the bearing that is measured. Crankshaft bearings should be measured 90° to the parting line. By design most crankshaft bearings have an eccentric design, which means the wall thickness at the parting line is not equal to that at the 90° center line.

The purpose of the eccentric design is to compensate for casting distortion during operation, create a “wedge” affect that promotes the formation of oil film, and for slight tolerance differences of the jointing components. To determine the amount of eccentricity, measure the bearing at the centerline and then at approximately 3/8” above the parting line since some bearings may also have an additional “relief” near the parting ends.

The amount of eccentric dimension and the presence of a relief cut vary by engine make and/or model. The center line measurement determines the amount of clearance between the bearing and crankshaft and is the common dimension given when wall specifications are stated.




#2) OIL CLEARANCE - RESIZED BEARINGS Clevite 77 recomendations

Clevite T 77 Example:
"The oil clearance shown in this catalog are for the factory
manufactured precision sizes. When installing a resized
bearing, adjust the oil clearance shown as follows:
For babbitt and TM-77 copper-lead:
Add .0004” (.010mm) to both low and high limit
For TM-112 copper-lead:
Add .0008” (.020mm) to low limit and .0004”(.010 mm) to the high limit"


#3) Typical values of the crush height of 1.5-2.5” diameter bearings:

For passenger cars: 0.001-0.002” For high performance cars: 0.002-0.004”.


#4) Blue print oil clearance on a blue printed tight tolerances re machined engine!
Clearances I look for:
Grocery getter .001" High performance cars .0015 to .002 depending on
oil pump pressure the higher the pressure the more I can increase the oil clearances on a race or drag car !!
----------------------------------------------------------------------------
I cut and pasted this!

"Higher oil clearance causes an increase of the oil flow passing through the bearing and resulting in a lower oil temperature rise. However higher clearance produces less uniform distribution of the oil pressure - greater pick pressure, which increases the probability of the bearing material fatigue. Minimum oil film thickness decreases at higher pressure and may cause direct metal-to-metal contact between the mating surfaces. Too high clearance produces excessive vibration and noise. Lower oil clearance results in a more uniform oil film pressure distribution and a greater oil film thickness however too small clearance causes overheating the oil and a sharp drop of its viscosity. High performance bearings has an increased clearance providing more stable hydrodynamic lubrication under conditions of high loads and high rotation speeds." Typical values of oil clearance C :

Passenger cars:

Cmin = 0.0005*D Cmax = 0.001*D

High performance cars:

Cmin = 0.00075*D Cmax = 0.0015*D

where D - the journal diameter.








Jester
 
#23 ·
No worries- I didn't take it any way other than just what you said, and I agree. IMO the readings given by a strip of plastigage is not what one would use to do precision machine work by, but plastigage is certainly better than nothing, and is good for double checking.

I have a lot invested in my measuring tools and nothing is better than to mic a journal or measure a bore and have it be what it's supposed to be!
 
#25 · (Edited)
The plastigage statement is very important to guys that its all they use or depend on!!! If a guy uses it and it reads .0025 and its off by .0015 that would mean: if the max. was .003 you would actually be at .004" or .001" over maximum clearance! Im not saying a guy in his yard or home garage cant build a good engine without owning expensive tools! I'm saying a guy who has expensive tools may think the reading on the plastigage is spot on and reading good on all the journals and actually be over the maximum allowed oil clearance limit!!!

Those pictures look blurry when I enlarge them to these old eyes!! I see the silver and gold color but cant make out details like the bluing! Its hell aging!!!!!LOL
Jester
 
#28 · (Edited)
I got this from Clevite:The 4th coating on on a trimetal bearing is for storage. called a flash plating.

FLASH PLATING - Most trimetal bearings use what is called a “flash plating”. This is an: extremely thin layer (approx. .000030’) applied all over to provide uniform appearance and protection from rust and oxidation in storage. The common flash platings are either an alloy of lead and tin ranging from 10 to 20% tin content or pure tin. Pure tin has a more whitish color while the lead-tin alloys are a medium gray color. Both have a satin finish.


This is what mousefink was talking about "sliding layer" earlier! I mentioned a slide coat as we called it many years ago! I guess its called "flash plating" now. The 4th plating on on a trimetal bearing is for storage.


Jester
 
#30 ·
Let me ask this. When your getting a block machined or just planning on rebuilding one do you have to have it line honed or does the block need checked for any other clearences. Just asking to see what you all will say compared to what my machinist said. Have a feeling Im gonna be p i s s e d. Think Im gonna need to go somewhere else.
 
#34 ·
I would expect the machinist to bore, deck and square the block like you asked him to do. Then if you wanted the saddles checked, he should be able to say whether they're OK as-is, or if they need honing, or if they need bored first. But a lot depends on what you have instructed him to do.

This is probably better answered by a machinist, but I'll take a stab at it:

You get a line hone if the saddles are close but not perfect. It's done routinely by many machinists for high performance builds to assure a good foundation. There are MANY little nuances to this as far as how much material is removed from the caps, chamfering the bores, mounting an oil pump (or part of one) to the rear main cap, etc. So I don't want to make it sound like it's a total no-brainer to do.

You would only get a line bore (followed by honing) if the saddles were out more than a little. This requires good equipment and a good operator w/a good touch. It may be easier/cheaper to get another block to use if the one you have needed line bored.

As far as do you HAVE to hone it? Often no, you don't. If the block is only going to be used as a street engine w/a mild build, as long as the saddles are reasonably close you can use it as-is. Not an ideal situation, but everything you do adds to the cost and you have to draw the line somewhere, else you'll end up w/a production block that will cost nearly what an aftermarket block would cost.

So what did he say and what are your concerns?
 
#32 ·
I always had 60 psi at start up everytime and never had any start up problems. I dont know, now Im thinkin about just junkin this crank and just makin this a 377. Actually ill keep the crank for a later project cause it looks good. I cant see any wear. But do I need to have this block line honed. I dont think I do. I guess ill need to mic it to make sure. Anyone know where to get a good cheap mic??
 
#33 · (Edited)
You need to have it checked!!! Or if you have a machinists long straight edge and good feeler gauges you can get a good Idea if its straight or not at home. There may be nothing wrong with the block? we are all just making good guesses LOL! We cant tell you if you need a line bore or not from a computer!
Maybe all the worn inserts had real tight oil clearance and the better ones had max oil clearance putting them further away from the crank, or some debree was under a few during assembly, maybe the good ones had just a little more coating then the rest, maybe at one time just your good looking inserts were changed during an inspection in the past or if there was a problem and the others were left alone because they checked ok etc, etc!

Check the pawn shops for tools a lot of machinists retire or upgrade and you can find them there!





Jester
 
#35 · (Edited)
I was just curious cause I took my 73 chevy 350 block (which is not the block I took the crank stated above out of) to the machine shop which was the first time I ever been there but herd alot of good things about it. Here is the deal. I called him up one day and told him I have 4 chevy blocks and 8 pairs of heads and two intakes that I want to do some trading for some block work. He said well bring up what u got and Ill look at it. I took it all up there and he said we can work something out. He asked what its for and what I want done to it. I said its a street/strip build. If it needs bored do it 30 over which he said it does. also I didnt have the main caps so he said he would give me some and line hone it. Also first thing he is gonna inspect it, magnaflux it for cracks. I told him I wanted him to square it up and deck the block. I think thats all I told him, cant remember it was over two months ago. Someone told me on my 355 engine build thread that he should of told me to have the pistons I was going to use with the block when I dropped it off. I asked hime that if he bored it over .030 could I just buy .030 pistons and use them he said yes. Also I said can I buy stock main bearings and not have to do any measurments. He said when Im done you can buy standard size everything except .030 pistons and install them with no problem. Someone said he is full of s h i t. So Im thinkin I traded parts for block work thats gonna have to be re checked after I get it What you guys think. Keep in mind guys and bare with me that this is my first performance build so I kinda went into it diving right into it asking more than knowing.

Thanks Guys...

ChevroletSS


Also guys I had one of the main bearings I took off the crank I been talking about that was not copper colored and its been sittin since last friday and I just checked it out and there was a puddle of oil sitting in the center of the bearing and where the puddle is the bearing turned copper. It was all silver colored before. So does oil cause the coating to wear off and turn copper???
 
#36 ·
He asked what its for and what I want done to it. I said its a street/strip build. If it needs bored do it 30 over which he said it does. also I didnt have the main caps so he said he would give me some and line hone it. Also first thing he is gonna inspect it, magnaflux it for cracks. I told him I wanted him to square it up and deck the block. I think thats all I told him, cant remember it was over two months ago. Someone told me on my 355 engine build thread that he should of told me to have the pistons I was going to use with the block when I dropped it off. I asked hime that if he bored it over .030 could I just buy .030 pistons and use them he said yes.
The piston to bore clearance will need to be checked to be sure it's OK. He really should have had the pistons before doing the final hone, though. That said, you're prob. gonna be OK, as long as you buy the kind of pistons he honed it for- cast/hyper pistons are fitted closer than forged pistons.

Also I said can I buy stock main bearings and not have to do any measurments. He said when Im done you can buy standard size everything except .030 pistons and install them with no problem.
Unless you are getting a new crank or a polished used crank, you cannot use standard bearings.

He might have meant that you can install the crank w/the right undersize bearings and it will fit. Or it might just be a polished crank. There will be a big difference in the cost of polishing as opposed to turning.

Also guys I had one of the main bearings I took off the crank I been talking about that was not copper colored and its been sittin since last friday and I just checked it out and there was a puddle of oil sitting in the center of the bearing and where the puddle is the bearing turned copper. It was all silver colored before. So does oil cause the coating to wear off and turn copper???
No. If the oil was acidic enough it could dissolve the plating if it's zinc, tin, or something like that. But uncontaminated oil will not touch it.

My turn.

Out of the 4 blocks you traded him, there wasn't one that could be bored 0.030" over that had all the caps?

BTW, you will be awfully lucky to get by w/just a main hone if he's replacing all the caps.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top