bearing choice forged crank

larrym

larrym

West Coast Newfy
Joined
Jul 17, 2007
Not a race car but a street car, I have had good luck with the ACL duraglides on a stock crank.
I know there should be no real difference but I figured I would ask.
 
the forged have a radius which is different than stock which is rolled into the crank
this results in a narrow bearing surface you need to watch the bearing doesnt hit the radius

im running the Federal Mogul 107M on mains and had to go to the ACL CB1228 on the rods , the wider FM race rod bearings would need to be chamfered
 
What P/N's on the King bearings? I'm looking at a kit that comes with King MB443AM mains and CR6616SI rod bearings.
 
these days with many bearing sizes being discontinued i use whatever i can find that fits ------ more and more variations in bearings seem to be showing up ------- i have seen standard bearings that measure thicker than .001's -------- it is very common to find thickness variations within a box of bearings and almost normal to find variations from box to box regardless of brand -------- sometimes i spend hours picking through different boxes of bearings to find something that will give the right clearance ------- very often i find i have to use combinations from different brands to get things just right---------i can't remember the last time i opened a box of bearings and found them to fit with no mix or matching--------the newest batch of Eagle cranks are priced right but seldom can you find one where all the journals are the same size
 
I completely agree with Richard. Getting consistent sizes is not possible. I have about a hundred rod bearings on the shelf so I can sort and get the clearances right where I want them. Just assembling with any ole clearance is a recipe for disaster.


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Thanks for the replies! Any concerns with bearing material/construction?
 
I prefer Trimetal bearings, They conform better, embed small particles and handle loads better than Bi-metal bearings. But there are people who use the Bi-metal bearings and swear by them.......to each their own!!

DR
 
Arn't bimetal more of a performance bearing and designed to fit a little looser for higher rpm applications.
 
They just aren't known for there creamy outer layer. When crud goes through a bearing journal with a nice thick layer on top, it can get buried below flush and stay off the crank journals.

Personally I'm still on the fence depending on if it's better to bury it and hope it stays out of the way, or letting the debris just get spit out and not sequester it. With my engines I choose the latter.
 
Bi-metal bearings are lead free.......steel shell with aluminum overlay. Tri-metal is steel shell , copper-lead in the middle and a thin babbit top layer.


Alumium is unforgiving when dirt and misalignment is involved. Most bearing manufacturers will tell you that a bi-metal bearing is not for performance use. Most new engines use Bi-metal bearings......not because they are better or stronger......but they are lead free and cheaper than bi-metal.

Most diesel engines are using trimetal bearings.......why? because bi-metal won't stand up under the extreme pressures.


I've attached what I think is a great article on bearings from Mahle Clevite for anyone who wants to read some more on the subject. Ya they throw alot of their marketing rah-rah stuff in there but it is full of good info on bearings.
 

Attachments

  • Mahle Clevite Bearing Article.pdf
    4.5 MB · Views: 1,085
Nothing handles a load like a babbitt bearing. As the babbitt becomes thicker,it looses strength. This problem was solved with the invention of the tri metal bearing. As turbodave231 stated,the tri metal bearing has a steel shell with a layer of copper-lead with a thin layer of babbitt. It is this design that allowed them to get the babbitt thinner to increase strength. The final additive to increase durability is indium. This was discovered and used in WWII airplane engine bearings. This final additive of indium is what makes a Vandervell bearing special. They are not in business anymore. If you can find some of these,grab them. There were also some versions of Clevite and possibly others that will have a V in the prefix of the part number. These will also have indium in the formula.
 
I like the Clevite H bearings and used them in several engines. The CB1398 rod bearing is the only Buick V6 H series Rod bearing. It is a wide bearing and must be narrowed in order to be used on a forged narrow journal crank (or they rub the fillets). That is a lot of work when narrow bearings are already available. If you're using a wide journal crank, The H bearings are the only way to go!!!! Last time I checked, the CB1398's were available in (Std), (+.001") and (-.001"). This makes it easy to get your clearances correct.

I also agree with Kevin, Coated bearings are an insurance policy.......It might just save your crank if you get into boundary lubrication.
 
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