Dave88LX

Rebuilding w/ a Scat 9000 crank. Engine builder said H's for a street light strip duty, but one guy who I'm talking to getting the Rotating assy from says he usually does P's with a cast crank.

$20 vs $60 on the bearings....

From what I understand, P's are softer and more forgiving to absorb contaminants, whereas H's are a harder, better performance, but not as forgiving and need more strict oil maintenance etc.

Please advise. I'm looking to make ~450ish at the flywheel....

akafred

um i dont realy know the diffrence but my stroker is getting v bearings

treyZ28

I would go with a H personally, I did.

Sprinning high R's I wanted a harder bearing. I change my oil and filters frequently and thats what my machine shop said to use so i did. He also advised me agianst doing this for cam so go figure

Dave88LX

Thanks Trey...

Some say go P's b/c they're more forgiving...looking for more opinions....

Dave C. '97 Z28

You run a soft bearing in a race engine because you want better embedabilty so that if something internally takes a crap and you get metal particles or something in there then it will embed into the bearing rather than trashing your crank or rods. But the downside is they wear out faster. But since a race engine is usually rebuilt on a regular basis you trade durability for permablilty.

Street bearings are 'harder' so they will last many thousands of miles without having to be replaced, but they are not as permiable as a race bearing. Of course, under normal circumstances people rarely get metal shavings in thier motor unless something breaks.

So if you want to replace your bearings more often, get the race ones. However if your car needs to be together for a while like a regular street car, then get the hard ones.

Get the regular Clevite-77 street bearings and you'll be fine for high-performance street.

-Dave C. '97 Z28

PS: The Scat 9000 series is a good crank. I've got one in my big Block. It miked out perfectly and had 0 runout.

Gripenfelter

My engine builder used H bearings as Trey has suggested.

Built it for durability because I don't drive the **** out of my car and I don't expect it to go boom.

Dave88LX

OK you've kind of lost me now...

I thought P's were softer, better for a street car because the bearings were more forgiving. The H's are harder, better for racing, more strict oil attention is needed...less forgiving.


???

EddieP

You are right - the P's are softer, and considered more of a "street" bearing, while the "H" bearing is considerably harder... I went with the P bearing on my engine build-up. If you plan on putting a decent amount of miles on the motor, the P bearings are probably the safer bet... not to mention cheaper.

Mindgame

I'm assuming the Scat 9000 cast cranks have oversized fillet radii? Then you need a chamfered bearing designed to work with that type of crank. Talking Clevite.... the "P" series isn't, the "H" series is.
As for bearing durability, the difference is in the backing layer. Keep the oil clean, keep a close eye on engine wear and signs of abnormal wear and you'll never see a difference in durability between the two.

-Mindgame

rskrause

Find your answers here: http://www.engineparts.com/products/bearingtech.htm

You want "H" bearings, as 'game suggested.

Rich Krause

EddieP

Dave,

Do your self a favor and call Scat directly on this- I had the same question regarding P or H bearings with their crank, and talked with them at length about it... both will work with their 9000 crank, but the 'P' seemed like a better bet for my daily driver.

Dave88LX

Can someone give me the exact part #'s for the H-series Federal Mogul Main, Cam, and Rod bearings?

I want to make sure I get the right ones.

Are any of you running Kings alecular bearings? I'd like those part #'s as well...

Dave C. '97 Z28

Actually, for a race engine you want the softer bearings and for the street engine you want the harder bearings.

It is assumed you will be rebuilding a race engine regularly so you want the bearings soft so they catch any particles from 'problems' (like other parts breaking) and prevent your $2000 crank from scoring. But because they are soft they wear out quickly and must be replaced regularly, but that's okay because a 'real' race engine is generally torn down regularly for inspection.

In a street engine the engine will be driven for many miles so you want the bearings hard so they retain thier shape and don't wear from incidental contact (like during startup).

The difference between a 'race' bearing and a 'street' bearing isn't that the tolerances are better or anything, is mainly just how soft the material to catch debris. But a 'race' bearing is too soft to be used in an engine that won't be torn down regularly.

I used a Scat 9000 in my big block and the clevite-77 bearings were chamfered enough to clear the filets without any trouble. But that's something you should always check. If your thrust clearance is real tight, then that could be a sign the filets are close to binding, even if the crank turns freely. Trust me, you don't want the crank to thrust against the main bearings (except the thrust bearing)...bad things happen remarkably fast when that happens.


-Dave C. '97 Z28

96ZUL8TR

don't know which scat 9000 crank that you are going to use but be sure to balance it. i have a 3.75 internal balance, one piece and with both the stock flex plate and the sfi one that i puchased, we had to knock the weight off to get it to balance. if i didn't that route it would have required 850 grams to taken from the crank. oh i am using the h- bearings.

Dave88LX

Yeah I've already got the assembly balanced.

So an H = harder for the street.

I want Federal Moguls though. Have to cross the #'s I guess...actually I want Kings alecular bearings.

This is gonna be a street car with some track time. I don't plan on tearing it down.