I'm just starting in assembling the 427 for my 65 396 Roadster. I was about to test fit the crankshaft and pulled out the new Clevite Bearings and saw that they were black. Not as if painted black but have this odd black kinda sooty coating on them. If I wipe them lightly with WD-40, some of the black will transfer. Not a lot but it's not something I was expecting. Anyone ever seen something like this?
Mike T - Prescott AZ

 

No, I haven't. And I've seen a few bearings. Wondering if it's a protective coating (not needed) or supposed to be a running surface? Also, how thick is it and what effect does it have on the clearance measurement? I'd feel more comfortable using normal bearings that weren't painted/dyed, etc.

 

They look used to me. Stained by hot oil, radial wear and worn to the copper on the thrust surface. I wouldn't use them but that's me.

Tom

 

That's normal for H bearings. You are probably used to looking at P bearings. H bearings are high performance. This is their normal color right out of the box. No paint no dye and these are not coated. HK bearings are Teflon coated.

 

Wow. Never heard of HK bearings. Learned something new! Thanks!
They still look ugly though.
Tom

 

Standard engine bearing are either tin plated copper based material or aluminum. Both are silver in appearance. For over 20 years now performance bearings at least those from Clevite and Federal Mogul eliminated the tin plate to maintain more precise size of the finished bearing.
when they first came out we called them UGLY bearings. But they work. As I recall the standard bearings are 77% copper. Race bearings are 83% copper. The steel bearing back also is upgraded from 1010 to 1020, a harder and stronger material.

 

Whew - Thanks for the info, Robert and Mark. These were purchased maybe 8-10 years ago when I was living in Northern California and I'm now in Arizona, another not-so humid area because my first thought was that it was some form of corrosion and these were just removed from the protective plastic wrapper. I did notice the plastic wrap did have tiny breathing holes here and there but now I see I don't have to worry about them.
It's a new one on me too, I suppose I was used to seeing the generic 'P' type bearings in the past.
Thanks,
Mike T - Prescott AZ

 

I should know know the answer to this but honestly I don't. The steel plate the bearing is made on is slightly harder but tha has no affect on the bearing material hardness. I always assumed when buying H bearings they were superior to P bearings. But I think they may be the same bearing with a few different treatments. First as 'Mark said they aren't tin plated which is what you see. H bearings are either chamfered for large crankshaft radii or they are made narrower. The rods bearings used to be chamfered but Clevite figured out hey we can just make them narrower and accomplish the same goal. The mains are still chamfered. The oil holes are usually bigger than P bearings. H bearings have more eccentricity, meaning they have more clearance going up each side of the bearing from where you would measure vertical clearance. This is where they differ from P bearings. The bearings are held in a fixture and bored this is how the control eccentricity. In the past H bearings were bored and P bearings were broached. I don't know what they are doing anymore. I always used H bearings in race engines and P in stock rebuilds. I used coated bearings but not Clevite's. There are a few companies that coat engine parts. For years Clevite said coating was totally unnecessary. Now the LT4 engines come with coated bearings. And just so you know you cannot buy bearings in Europe with any lead in them. Car manufacturers had to change bearings to comply with this.

 

Robert you are correct, the bearing material is sintered on top of the steel bearing back. They use Aluminum, several differing formulas, Copper/Lead/Tin was the standard forever and pretty much still is on Performance and Diesel engines but the standard copper blend is 77% copper, ( where the name Clevite 77 first came from) the performance blend is harder and 83% copper still mixed with Lead and Tin. You are correct, Copper, Lead and Tin are all on the endangered list. Versions of Aluminum Bearings keep getting better and some now far exceed the capability of the old Copper Lead Tin. In stock engines more than double the bearing life is now available using Aluminum bearings.
The 1020 steel bearing back is used in both Performance Bearings and in Heavy Duty Diesel engines. Bearings can distort under extreme loading and the 1020 holds up better against distortion. Most Gas engines, non turbo or other non boosted applications are just fine using standard bearings and 1010 steel. If high RPM is going to be part of your engine, above 6,000 or if you are above 450 HP you might consider the performance bearings. the performance bearings are designed to allow for connecting rod bearing oil flow at high RPM. The clearance at the Rod Cap parting line by the rod bolts is increased to allow for rod stretch at high RPM. Stock bearings can start closing off this oil flow on rods at RPM's above 6,000. As the rod stretches it starts closing off your oil clearance at the parting lines. The negative to using performance bearings in a stock engine is you will see slightly lower oil pressure as they will leak more oil at normal RPM levels but provide more protection at high RPM levels. Rod stretch actually only happens on the exhaust stroke as the rod is trying to jerk the piston back down.
Hard to see in the pictures but these may be a factory Moly Coat on the bearings, it is used and has been for the past 20 years on Rod and Mains for performance engines although I believe Federal Mogul stopped supplying coated bearings a few years ago for Performance engines.
The coating is there to help should you ever have a short term oil starvation. High end racers started demanding coated bearings back around 1999. Same idea as coated pistons skirts. Another layer of protection against failure.
Federal Mogul Started boring Bearings in the late 90's when they came out with the high silicon Aluminum Bearings. Other than these special aluminum bearings I think they are all still broached to size. Not sure what Clevite is doing but I bet the same. I have been out of touch for about 10 years now so maybe they are all now bored.

 

The softer the bearing, though, the better the 'imbedability', which means that they can soak up and absorb small bits of trash that can lead to journal scoring with a harder bearing.
Rather than use the narrow 'race' bearings in my recent 383 build, the machinist showed me how to chamfer the rod bearings so the engine would turn over with my large radius crank. He likes chamfered bearings VS the narrow race bearings due to the increased swept area of the bearing. Great thread, learned a LOT!!

 

I probably spend more time with bearings than anybody but the manufacturers. I have a date with these for my holiday weekend. I modify them so people can build their 377" SBCs. Been doing them for 31 years that's a lot of bearings. In the 90s and early 2000s I did a lot of these. They have tapered off quite a bit and that's great for me I'm old. This year has been different due to the virus, one of the manufacturers of the spacer bearings hasn't made them because of the virus. It's really hard to believe people still do these in these numbers or can still find 400 blocks.







Blow P bearing on the left, H bearing center, teflon coated bearing right. I always used teflon coated for race engines whether they were necessary or helped. They almost changed my mind once during a conversation with the coating rep. I said "well y'all just spray the coating on over the original bearing anyway". He says no we abrasive blast the bearing so the coated will adhere. I was asking because the first company I used to apply the coating had no quality control the bearings would vary as much as .004" inside after coating. I asked if they measured after plating and the answer was no they'll wear in. I didn't like that response.



Jeff these are the imbedible bearings they are softer than the aluminum bearings. I still can't get to where I can use aluminum bearings. Any trash or foreign material and you've got a bad day.

 

In all out racing I believe the Copper Lead Tin bearings are still dominating use in engines. At the OEM level Aluminum Silicon enhanced bearings took over back in the mid 90's and the manufacturers that embraced that technology have bearings that look new after 200,000 miles use. The reason FM quit selling coated bearings was they did not have the ability in house to coat them, they contracted out to a specialty shop and they could not keep up with demand at that time. FM's plant was running at full capacity already so they did not want to add another step that demanded more time to produce the specialty bearing. The Coating on bearings does vary in thickness. Bearings are built to proper size. Then they are coated. The coating is sacrificial, you are instructed to ignore the coating when sizing your oil clearances. On pistons or on bearings the coatings will wear in to fit your engine. On pistons the coating is applied with a silk screen process and the thickness will fluctuate, I have seen one with a run in it. Not a problem as this is sacrificial. The coatings do work. I was at a shop that tore down a severely overheated engine. The pistons were coated and not one had any damage. Head gaskets were toast but the pistons survived.
Chrysler chose to not use the new silicon enhanced bearings and went overseas for lower cost bearings. They have paid the price with many engine bearing issues on several engines in their platform. The 2.7L V6 was the poster child for this. Ford came on board first with the high silicon engine bearings. I was calling on rebuilders around 2000-2004, these guys advertised that all of their remanufactured engines had a freshly ground crankshaft. I remember one owner of a shop that did between 1,000 and 1,500 engines per month calling me and discussing his problem. The new Ford engines, at that time it was the 3.8L and 4.6L, 5.4L had crankshafts in them that measured full size had zero wear and the RA finish was around 10. These went into the engines with an RA between 12 and 16. So the cranks were full size and smoother than the OEM new crank. The high silicon bored aluminum OEM bearings polished the crank as the engine ran. These engines had over 100,000 miles on them. The owners question is, what should he do. The cranks were better finished than his re ground crank but he would have to use standard engine bearings and any customer that tore down one of these engines would know he did not grind the crank. His advertisements say he would grind all cranks. So he had to re think his program to match the newer engines. These early bored bearings had a horsepower limit. I think it was around 400-450 HP at the time, FM called that bearing the A500. The bored surface of the bearing is very hard and it is threaded. Silicon enhanced aluminum holds its shape very well. These are bored so think threaded on the face of the bearing. Rather than having particles embed in the bearing the particles swirl through the threads and are flushed out of the bearings and hopefully get caught in the filter later. The threaded shape also holds oil. You can park these engines for weeks and the oil sits in the threads so the old problem of dry starts with no oil sitting on the bearings is gone. This alone increases bearing life dramatically. The problem with embedded particles in bearings is that it always comes back to haunt you later. In a race engine that is not an issue, later it will have new bearings some get new bearings for every race. In a passenger car something embeds at 10,000 miles and is fine. At 20 or 30,000 miles that embedded part starts to protrude and starts cutting on your crankshaft. Remember looking at crankshafts in the old days coming out of engines. You would see lines in all the crank journals that circle the journal. Some were very minor some were deep enough to catch your fingernail on. These are caused by embedded particles. They always come back to haunt you later. This issue is eliminated with the silicon enhanced aluminum. The crank comes out looking beautiful unless someone starves the engine from oil. No oil will ruin any engine bearing.
Somewhere around 2002 Federal-Mogul introduced this new technology to Mercedes, the Mercedes engineering staff said no way, they will stay with tri metal bearings, management said they had to test the new material. There are well known bearing tests that simulate a full lifetime of use in a car that they can do in a few days. The Mercedes OEM bearing failed, the FM bearing looked brand new. Engineering said this was not possible and tested the bearings again. Same result. Now Management said to switch to the new bearings, engineering insisted the test data was flawed. They brought in a recently retired Mercedes bearing expert and had him run the test this time to verify a good test. He ran the test, same result. He looked at his old team and said this bearing is much better, Use It. Germans are very good engineers but not quick to change or embrace new ideas that did not come from their shop.

In the early 2000's I do remember some performance builders installing the new A500 bearings in engines making more than 400 HP and we did see some failures. Since then I know the A500 was upgraded to A600 and they were working hard on a new A650 that was supposed to replace all Diesel and Performance applications but I am not in the loop anymore. Don't know if the A650 is in production or if another version has superseded that product. The EPA plans to ban Lead, Copper and Tin from production ( i think 2020 was the ban date ) so they are working to make that happen and I suspect they have already done that but as recent as 2 years ago the high load bearings were still 83% copper on 1020 steel. At the production level the High Load bearings were not the Corvette with 725 HP it was the Heavy Duty Diesels, some of the Caterpillar Diesel engines were using as much as 60 pounds of turbo boost in working engines. Engines that run 24/7 in that high boost environment and are expected to go 1 million miles between rebuilds need strong bearings.
There you have it, a long winded answer but gives you some history. Hope it helps.

Our classic Corvette engines will probably never see another 200,000 miles so what bearing is installed will probably make no difference to most of us. I am building a SBC 400 with AFR Heads and I will be using the old style copper lead tin because I have them already in my garage, these are good bearings but I know there is better stuff out there today. Look at the new OEM engines and the Horsepower they are making with Turbo's and Superchargers. 4 cylinders making 280 HP, 8 cylinders making 750 HP. Stock Truck Engines are making over 400 HP naturally aspirated and the bearings are holding up very well so the new technology is not hocus pocus it is really cool cutting edge stuff. Many of these new engines are running 300,000 miles.

 

If the black transfers, it is prodably moly disulfide.

Moly is good stuff, and does not build thickness, it gets into the pores of the metal.

Doug

 

You sell those bearing spacers to forum members? I have 3 standard bore 400 blocks.

 

Robert is that new old stock or King Bearing spacers for the 400 to 377 conversion? You have quite the selection.
Mark

 

Those are new Clevites. I modify them for the 377 conversion. King is competition. A manufacturers rep that used to come in once said King will make those for y'all. We told him we didn't want any help with that. He went and got King to making them. It's ok I've made all I've wanted to if I had to guess around 25,000 sets.