I have been using Clevite bearings for a long, long time (professionally).
I have had a problem with Clevite cam bearings in the last 3 Chevy SB engines I built.
The bearings fit fine on the cam, but when I press them into the bearing bores, they are too tight on the cam. On one engine, I only had a problem with #1 bearing. On the current engine, I had a problem with #5, and #3. I bought a second set, and now I am having a problem only with #1. I have never had these issues in the past... Clevite cam bearings just pressed right in, and the cam spun perfectly. Lately, every engine I do, I have problems with the Clevites. Anyone else have these issues?

Just for grins, I honed the #1 bearing to get the cam to fit.... but this is not acceptable... they should just plug-n-play.

I tried 3 different cams in the same bearing... all 3 were too tight, one is a brand new cam. The cam journals are in spec.
The bearing was tight only along one edge... so I popped it out & reversed it... the problem followed the edge to its new orientation. So, it's not a block problem... definitely the bearings. I have a good KD cam bearing installer set that I've been using for over 20 years... never had a problem with cam bearings until recently.

The tool prevents the shells from getting nicked or deformed.

3 blocks... 5 sets of Clevites ($10 sets)... all problematic.
These engines don't warrant anything better than a $10 set.
Any ideas? Are they having manufacturing issues?
I checked the blocks for burrs, but not for core shift.

Please... I need input from people who actually install the bearings.... not people who had them installed by someone else. An unscrupulous mechanic might hone ill-fitting bearings just to get the engine finished and collect the money.... so the owner would never know.

I need to know if anyone else is having this problem so I can either switch to a different brand, or, look for a different cause.


Tom

 

Are you honing the bearing insert after installation ,, or honing the hole itself ? I would not hone an insert myself , as the bearing layer would become contaminated with grit from the hone . I always intall the front bearing from the rear of the engine , as you well know I am sure installing cam bearings is a pia ! I once ran into a damaged cam bore on a 312 57 t bird engine ,,, I wound up having the hole machined oversize and I machined a bearing insert from billet stock . It was a numbers matching car in show condition so the owner was glad to pay . I have run into some snug fits on these chevs before , but nothing that would cause problems .

Gman

 

Tom:
I too have been using clevite bearings for many years. However, I have not recently experienced the problems you mentioned . About ten to fifteen years ago I had problems with certain bearings as you mentioned. At that time I replaced the offending bearings. Perhaps it's a manufacturing issue with a certain lot. I havent looked but there may be a lot number on the bearings or the boxes they are shipped in. I currently use a cam bearing installation tool I machined from stainless. I just installed cam bearings in a SB last week and had no problems.

 

i had this problem 1 time years ago so after that i always used a small cly hone to just touch up the cam bearing bores in the block to make sure there are no nicks or rought spots in the bores. the time i had a problem i had to hand scrape the ID of the cam bearing to get the cam to fit correctly because the rotating assy was already in the block so trying to get the # 4 bearing insert in and out of the block to scrape was a bitch. i always checked for cam fit before engine assy after that. :mad :chevy


[Modified by clem zahrobsky, 6:15 PM 5/13/2003]


[Modified by clem zahrobsky, 6:17 PM 5/13/2003]

 

Ram82fire...
I honed the bearing just to see how much the ID was off from spec.
It's trash now.

Clem...
The crank is already in the block with a new seal, so I don't want to pull the crank. I failed to test fit the cam in the new bearings before I dropped the crank in. My bad... I assumed it (new 327/350 cam) would fit okay because the old cam spun freely when I removed it.

Kingt... did you use $10 Clevites on that SB you just put together?

I had trhe same problems with a 350, a 305, and now a 327.
Yet, I did two 302 Fords (Clevites) and an import in between with no problems.

 

Yes, they were the $10 bearings.

 

I just went through this one with my 396. After measuring the bearing shell thickness, I found that they are not all the same. The middle cam bearings are slightly smaller in outside diameter. I assume that when they bore bearing journals in the block at the factory, the outter bearing bores are slightly bigger so that they can get the tool in and out?? Anyway, if you put the bigger bearings in the outer bores, you should eliminate the problem you are having.

Am I out to lunch, or has anyone else experienced this?

Once I put my bearings in the right locations, my cam turned freely.

Rob

 

That's correct... you can't just press the shells into the bores. They are "positional". Clevite provides a sheet in their package that tells you which bearing goes into which bore. The SBC package (SH290S) contains one bearing for #1 position, two bearings for #2 & #5 positions, and two bearings for #3 & #4 positions. You have to press each bearing into the correct bore position. The Clevite bearings are clearly marked, so no measuring should be required.

Also, the diameter of the SBC block bores does not correspond to the diameters of the cam journals front-to-back. For example, you cannot slide the bearing shell marked for position #5 over the #1 journal on the actual camshaft... the #5 bearing is smaller than the #1 bearing/journal.

Some cams are cut with all bearing journals identical. Some cams have a decreasing diameter going from #1 (front) to #5 (rear). Depends on the specific engine.
The inside diameter of each bearing shell is matched to a particular cam journal in this case. But... the ID and the "thickness" of the shell are not necessarily related. The ID of the bores in the block is independent and can vary according to its own schedule.

Maybe Clevites packaging is wrong though... I'll mic the next set to see what is going on.
The problem is that they do compress substantially when they are pressed into the block bores. They can fit fine when you slide them over the cam journals, but when compressed, they can be too tight on the cam. This is what is happening in this case. They all fit fine on their respective cam journals, but when I press them into the block, some are too tight, and the cam binds significantly.

The last 305 I did, I only had a problem with #1 bearing... I complained to my vendor, and he gave me another set. I pressed out #1, and pressed in only a new #1 shell, and the problem went away. This is why I suspect the product, and not the method.

Thanks for the suggestion.

Tom

 

Found this at Clevites web site... under tech stuff...

To meet the demands of higher loads and operating temperatures in modern engines as well as the requirements imposed by high performance, babbitt has been replaced by an alloy of aluminum. This aluminum alloy is much stronger than babbitt and will withstand several times the load which causes babbitt to fatigue or extrude. However, this added strength is obtained at the expense of some of the more forgiving properties of babbitt. The aluminum alloy is harder, making it somewhat less compatible with dirt, misalignment and marginal lubrication. This is typical of the compromises or trade offs that are frequently necessary when selecting a bearing material to suit the requirements of a specific application and in this case, higher loading.

Typically, whenever a higher level of loading is encountered, greater precision is required to maintain reliability. Conditions such as cleanliness, alignment, clearances, journal surface finishes and lubrication must all be controlled more closely. Following are some recommendations to help optimize performance when using aluminum alloy camshaft bearings.

So... I will assume I need to start align-boring the cam bearing holes on a regular basis.
She It.