Engine bearings Tri metal v Bi metal

[mach1charlie]

Smokey did that, no change in horsepower. Bearing rides on the same film of oil

[engineguyBill]

^^^^^^^^^^ THIS ^^^^^^^^^^^^^^

Chrysler did a lot of experimenting with roller bearings in the Gen II HEMI in the late 60's. Very expensive and didn't show any appreciable horsepower gains over the insert type bearings. As stated above the bearings ride on a wedge of oil, therefore friction is almost non-existent.

[swampbuggy]

BILL, when i was about 15 yrs old dad had me in a go-kart, i actually raced against Ricky Rudd in Barnesville Ga. appx. 1971. The 2 cycle engine we run in Jr. American reed. American made engine with a reed valve under the carb. It was a 6.1 C.I. McCullogh. That little engine had a 2 piece con-rod just like our modern V-8's. There was just enough clearance to install loose needle bearings appx. 3/32 diam., appx. 25 of them. we had to use grease to hold them in place until rod was bolted together. They were 1/4" shank allen bolts if i remember correctly. I have thought about why one could not do the same with a V-8. I got a feeling the crank would wear fast ???? Mark H.

[ProPower engines]

GM has been using the "A" series type bearings for over 20 years now in many different engine applications and while we think of aluminum as been a soft material in a bearing it is very hard when compared to a "P" series FM or Clevite bearing.

I have been using a lot of these A series in many different applications for years with no adverse affects to the crank journals or longevity of the bearings

The import engines have been doing the same thing even longer then the US car makers have.

I can remember being told do not use an H series race bearing on a cast crank for some reason it was said to wear the shaft faster. But when compared to an A series bearing I see no difference at all, now if a low oil situation occurs either bearing will grab the shaft but the A series will seemingly do more damage in a low oil case and faster.

While the forever used Clevite also has an A series optional bearing for most engines as does FM in place of the conventional "P" series bearing sets

Now this is base on automotive car engines where diesel engines bearing need differ greatly because of the extra high loads they see while in use they are constructed differently and have a much higher surface hardness and are just all around stronger materials being used. Thats for the engineer's to decide what the molecular differences are needed to be based on application alone.

That said I have been told by the bearing engineers at KING Bearing that a std. A series surface will not stand up to high loads when compared to a SI or XP series bearing.

We have seen bearing material flake out in places on the bearing surface where there is high load on a cast crank with a factory A series and the P series but not a harder bearing such as the SI and XP or H and V series of bearing and while the bearing is toast the shaft looked fine and would just polish and be good to go again.

It appears the engineer`s design a bearing based on power load and output of engines and use bearing materials as they see fit based on cost and longevity and only put as much as they need based on what is considered normal operation.

[hoodeng]

Any modern high grade bearing recommended by a manufacturer for your application is going to do what you need,with the crank prepped to their specs ,regardless of construction ,but the quality can be beaten by prep if not up to scratch. Manufactures like Clevite ,Mahle or ACL make top products ,and a follow up with Calico coating would be hard to beat.

Cheers.

[engineguyBill]

BILL, when i was about 15 yrs old dad had me in a go-kart, i actually raced against Ricky Rudd in Barnesville Ga. appx. 1971. The 2 cycle engine we run in Jr. American reed. American made engine with a reed valve under the carb. It was a 6.1 C.I. McCullogh. That little engine had a 2 piece con-rod just like our modern V-8's. There was just enough clearance to install loose needle bearings appx. 3/32 diam., appx. 25 of them. we had to use grease to hold them in place until rod was bolted together. They were 1/4" shank allen bolts if i remember correctly. I have thought about why one could not do the same with a V-8. I got a feeling the crank would wear fast ???? Mark H.

Back in the mid 60's (and maybe earlier than that) Mercury Marine used "cracked" connecting rods, as are used in many current automotive engines. They also used roller bearings in some engines during that time, as well. Don't know the extent of their usage or whether they are still used, but there were some Mercury outboard engines with roller bearings.

[engineguyBill]

I can remember being told do not use an H series race bearing on a cast crank for some reason it was said to wear the shaft faster.

This issue comes up from time to time, but there is no truth to the theory. The type of bearing does not influence crankshaft wear and vice-versa. The bearing does not know, nor does it care, whether it is running in conjunction with a cast, forged or billet crank and the crankshaft does not know, nor does it care what type of bearing it is running with. When running, there is an oil wedge that keeps the bearing surface isolated from the journal surface.

Proper (reasonable) vertical oil clearance; fillet clearance; oil quality and volume are the important considerations when choosing the correct bearings to use in any application.

[rfoll]

BILL, when i was about 15 yrs old dad had me in a go-kart, i actually raced against Ricky Rudd in Barnesville Ga. appx. 1971. The 2 cycle engine we run in Jr. American reed. American made engine with a reed valve under the carb. It was a 6.1 C.I. McCullogh. That little engine had a 2 piece con-rod just like our modern V-8's. There was just enough clearance to install loose needle bearings appx. 3/32 diam., appx. 25 of them. we had to use grease to hold them in place until rod was bolted together. They were 1/4" shank allen bolts if i remember correctly. I have thought about why one could not do the same with a V-8. I got a feeling the crank would wear fast ???? Mark H.

Back in the mid 60's (and maybe earlier than that) Mercury Marine used "cracked" connecting rods, as are used in many current automotive engines. They also used roller bearings in some engines during that time, as well. Don't know the extent of their usage or whether they are still used, but there were some Mercury outboard engines with roller bearings.

All of the Merc outboards I have worked on had roller bearings , both rod and cap. They don't require much oil, 50:1 oil in the mix does the trick. But boat motors operate at steady state speeds for long periods of time, and the propeller in the water means they don't experience the shock of a suddenly dropped clutch.

[4vpc]

Interesting read here: http://kingbearings.com/files/Engine_Be ... erials.pdf

[Newold1]

Thanks 4vpc for posting the King Bearing read, lots of new types and technology in engine bearings and King has a great load rating system for choosing the correct bearing for various uses.

rfoll:

Not sure you have ridden in any offshore race boats in big water but the engine loads in, out and re-entering the big water will definitely top dropping a clutch ANYDAY!! I've got a bad back to prove it!

[pdq67]

Probably need to mention to reverse polish all cranks so that any, "fish-hooks", generated by the grinding operation are polished off.

Of course this goes under, "crank prep"!

"Shoe-strings", of old, "crocus cloth", does nicely here if not mistaken.

pdq67

[engineguyBill]

Yes, when polishing a crankshaft the direction of rotation for the crank and the direction of rotation for the crank polisher are very important during the polishing process. Clevite engine bearing catalog explains the correct direction recommendations.

[MadBill]

Of course if the bearing 'always' rode on an oil film, it wouldn't matter...

[user-23911]

How many people are aware that some Honda cranks spin the "other" way?

I've used both a machine polisher AND polished by hand.
Polishing by hand is best because you do both ways at the same time eliminating any problems.

[rfoll]

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Thanks 4vpc for posting the King Bearing read, lots of new types and technology in engine bearings and King has a great load rating system for choosing the correct bearing for various uses.

rfoll:

Not sure you have ridden in any offshore race boats in big water but the engine loads in, out and re-entering the big water will definitely top dropping a clutch ANYDAY!! I've got a bad back to prove it!

I'm pretty sure that's far removed from anything I do.