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  #16 (permalink)  
Old 12-11-2012, 03:56 PM
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Main-rod bearings

Quote:
Originally Posted by ChevroletSS View Post
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??
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. 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

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  #17 (permalink)  
Old 12-11-2012, 04:24 PM
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Quote:
Originally Posted by hcompton View Post
I use hastings rings, regular old moly rings will work best in the old engine total seals are very expensive but not worth the money without prepping the bore for low tension rings. The part number of the box on my coffee table is .030 over but you can match it up with proper bore size.
Hastings 2m 139 030

The last number is the bore size these are .030 over. 4.030 bore.

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.

Acids do damage bearings by removing the coating of zinc and tin and other metals. Does not effect the copper or steel. Your proving my point here. Once you loose all the bearing material the engine needs new bearings. Plain and simple just like the ones in the pictures.

Bearing manufactures are hardly concerned that you need to turn the engine while building it. Modern engines are built by machine and all pistons are placed at once with the crank in second and everything linedup for install so the engineis not turned until it is started. Why would they patten a super coating that cost millions to develope if its totally useless.

Surely during the life of an engine it will see metal to metal contact. What if it sits for two years bearing can still get oil and be fine as long as the babbit material is still in place. Also hard corners or braking will cause lose in oil pressure. Crank will push the oil out in ms if the pressure is down. The only and entire reason plain bearings are made of soft metal.

Just for fun lets hear how making the rings grooves deeper can increase the ring gap aloowing a ring that is too long to be somehow shorter. If you have ever sized a set of rings you would know it does not envole the piston at all. I usally use my solid ring compressor to gap rings these days instead of using the bore to test fit.

To the OP sorry for off topic info. Had to let it slip.
Here we go! LOL

#1 the deeper ring groove comment is about a stupid person thinking it would work!!! not that you could actually do it!!!!!!!



Cast rings are forgiving!! They will form to an uneven or imperfect cylinder its the best ring to ignore imperfections!!! Molly coatings will wear off! Cast is considered forgiving has been for 100 years! The only thing to worry about is you cant role them onto a piston you need a spreader or they might break!! That's my opinion after 50 years of experience!

#2 I use Clevite And mic. them!!!! and find differences! There are no drop ins! You should have everything right before you even thinking about checking yourself with plastigage!! And you say they are drop in! Why would you use the plastgauge if they are drop in?????? What do you do on a blue print and ones a little too tight???? And bearing manufacturers are concerned about assembly procedures by builders and add the extra assembly coating its called "Quality"!!!

Being built by machines !!!!! Whats that got to do with this thread, Hes not a machine?????? This is about him building an engine at home!

Slapping together a rebuild in a couple of days isn't like a close tolerances engine!!!!! Even a stock Blue print!!! if the specs call for >.001 to .003 do you have your main journals all different 1 at.001", 2 at .025" and 3 at .003" etc. That's a half A S S build!!!!! They should be the same as close to minimum as possible on a good blue print or very close!!!!!!

The specs in the books are say .001 to .003 That's not the recommended clearance for persons new build!!! its clearances that are safe and when checking will suffice and an engine is ok!!!!! If you pull a pan and plstigage and get that clearance you can still run it!!! .001" is minimum needed, The .003 is max. over .003 it needs replacing!!!!!
If all the journals are at .003" with new inserts You have just built a wore out engine before its in the car!!!!!! 1,2,3,&4 mains need to be very close to minimum the same with all specs on the engine. Your machined block line bore and crank can be perfect but inserts aren't exact, you have to mike them !!!! and fit them to their best matching journal (like pistons to bores) if they don't come to the spec. order all 4 separately .001,.002,over to get a tighter clearance (or if too tight rework them)! The same with rods!!

I don't use plastigauge very often its inaccurate I do but only for a check with used dirty engines to get an idea! The reason many backyard engine builders like to use Plastigage is that they don't need expensive specialty tools like a mic or a dial-bore gauge. As long as the bearing surfaces on the rod and crank are clean, merely lay down the longer the strip the better the reading!

Read more: Plastigage Versus Micrometer - Accuracy Test - Car Craft Magazine


I never said anything about once the copper is showing they still good! I said "your bearings look good for that many miles!" 150,000 Miles after tear down!!!!!!

How does hard cornering and braking make less oil pressure??? Are you saying the pump pickup goes dry and sucks air? Or are you talking about race cars with no preventions for that or slosh! All the track tests by manufacturers led to designing cars that don't have that problem since the 50s!!! You haven't mentioned rolling a car on its top loses oil pressure and ruins bearings yet.


You said "Crank will push the oil out in ms if the pressure is down." "ms"?
If pressures down! Of course it does!! same with the cam! We aren't talking about engines wore out pumps with low oil pressure or wide clearance wore out engines! This isn't about coming up with scenarios on abused engines that's oil is never changed or run low or is left neglected setting for two years!! Its about normal wear over 100,000 miles!! On a well running car!! You haven't mentioned running it out of oil yet or driving it with a 2 inch hole in the pan, or never changing oil for the life of the engine!

I sent this early LOL I hit send instead of preview

Ill try to write the rest before I run out of time If you go to
Plastigage Versus Micrometer - Accuracy Test - Car Craft Magazine
And go on the picture I posted how far off plastgage is is pointed out!
All good mechanics know plastigage is inaccurate! And don't rely on its accuracy!!!!!!!!

Jester


This goes with the picture I hope it gets in the edit time!
Plastigage Versus Micrometer - Accuracy Test
After we torqued the rod cap and then removed it, we used the Plastigage package to compare its width to a particular clearance. While our careful mic measurements indicated a clearance of 0.0031 inch, the Plastigage indicated a much tighter 0.0015-inch clearance-or roughly half of what we mic'd. We double-checked our measurements, but the results were within 0.0001 inch.

Read more: Plastigage Vs Micrometer Plastiguage Photo 4
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Last edited by painted jester; 12-11-2012 at 04:53 PM.
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  #18 (permalink)  
Old 12-11-2012, 07:20 PM
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350 bearing wear

id definitely check your crank for trueness,as the wear looks uneven,calibrate everything,then as the other post get it line bored
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Old 12-11-2012, 07:45 PM
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Quote:
Originally Posted by RON MILLER View Post
.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.

Last edited by cobalt327; 12-11-2012 at 07:54 PM.
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  #20 (permalink)  
Old 12-11-2012, 08:13 PM
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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


#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 ????? 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

Last edited by painted jester; 12-11-2012 at 08:31 PM.
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Old 12-11-2012, 08:21 PM
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Just read your post Cobalt I didn't Offend anyone I hope:" My statement: "The reason many backyard engine builders like to use Plastigage is that they don't need expensive specialty tools" I didn't mean it to sound so bad!!! sorry!

Jester
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Old 12-11-2012, 08:22 PM
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worn bearings

i agree with what ron said as everything in his post is standard practice,at Suaro Automotive where i worked in Phoenix,everything from street to racing engines were went over with a fine tooth comb
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Old 12-11-2012, 08:38 PM
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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!
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Old 12-11-2012, 08:42 PM
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Cobalt,why i suggested line boring was the middle bearings show uneven wear,while the end caps show only bluing from heat this suggests there might be a problem with crankshaft trueness in the middle
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Old 12-11-2012, 09:21 PM
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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

Last edited by painted jester; 12-11-2012 at 09:26 PM.
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Old 12-11-2012, 11:23 PM
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Main Bearings

You top coating off the bearings ive seen this in engines with that many miles make sure the crankshaft is smooth when you replace the bearings mic the shaft and use plastic gauge to check your clearance when you install your new bearings.
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Old 12-11-2012, 11:46 PM
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Quote:
Originally Posted by hcompton View Post
.... 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.
What does that mean?
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Old 12-12-2012, 12:46 AM
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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

Last edited by painted jester; 12-12-2012 at 12:52 AM.
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Old 12-12-2012, 01:22 AM
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There's been debate over using or not using scotchbrite pads to take off the flash plating since day one.

What I do is wipe them off w/a clean cloth using acetone right before installing them at final. A dab of bearing assembly lube and that's it. No scotchbrite.
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Old 12-12-2012, 04:39 AM
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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.
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