Boosted One

iTrader: (6)

I'm building a 346 with H-beam rods, forged pistons, and a stock crank. I was told by some people to use H series bearings and by others to use P series (clevite).

What do you guys think? Are H series too hard for the stock crank? Or do I need them for the to take the added abuse of the "performance rebuild"?

Thanks
Frank

73ChevyC10LS1

i am also doing the same as you i went with federal mongul. for the rods i got 8-7100ch and the mains i got 7204ch

y2khawk

iTrader: (5)

I used H bearings on the rods, and OEM for the mains.

Boosted One

iTrader: (6)

Just curious, why not use the H series on the mains? Are the bearings too hard for the stock crank?

Would H's on the rods and P's on the mains be a good combo if I were going to use clevite 77s? Or should I just go with the OEM on the mains like Harlan?

Thanks
Frank

y2khawk

iTrader: (5)

I'd bet the mains are probably just as hard as the H series.

RX-Ben

iTrader: (7)

Why do you want harder bearings anyway? I'd think you'd want your bearign material to be soft to reduce damage in case the oil bearing layer was ever compromised.

Ben

Boosted One

iTrader: (6)

I'm not too sure, but I'm assuming it's for the higher stresses of "performance" oriented engines and strokers.

camrsz

iTrader: (4)

The main difference with the H and P series berarings is the edges of the bearings.
The p series has a 90 degree edge on the sides. H series has a rounded edge.

V8er

iTrader: (2)

Okay but what exactly does that mean to those of us building an engine? Is one bearing type better suited to the stock crank?

SStrokerAce

iTrader: (2)

The side of the bearing means how much oil you are going to trap between it and the crank. The bearings ride on a film of oil between the crank and the bearing. The narrower this wedge is the more force that is taken on that oil wedge per inch of surface area.

Think about it this way..... If you have 500 lbs of force pushing on 1 sq in of area you have 500 PSI, but if you have 500 lbs of force pushing on .75 sq in of area you now have 666 PSI.

The other end of this is that the wider the bearing is the more drag it has on the system which means more friction losses. Basically you want a wide enough bearing in your motor to take the loads the motor puts on it (either from inertia or compression) but narrow enough to not waste extra power with extra drag/friction.

Bret

SStrokerAce

iTrader: (2)

The stock crank doesn't have a rolled fillet radius on the edge of the journal (ie 90 deg radius) it has a back cut 270 deg radius so usually a wider bearing is used in a situation like this.

Bret

MUSTANGEATER

iTrader: (10)

Bret

You are just on fire today, answering everyone's questions. You must be bored at work today.


Your Pal,

Floyd.

SStrokerAce

iTrader: (2)

No I needed some more reading material and I wanted to check out some dyno charts....

Sometimes the reading here is better than TuckerMax.com

Bret

MUSTANGEATER

iTrader: (10)

Nothing is better than tucker max.