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I'm building a 393 Cleveland to go into my 70 Cougar, using a cast steel Scat 9000 3.85" stroke crank, a set of Eagle SBC 6" I-beams, and SRP pistons... I bought a full set of Clevite 77 H-series bearings for the rods, mains, and cam, and now after pokin' around a couple forums am wondering if I shoulda went with the P's. I'm building this motor up at my uncle's speed shop, and I'm no pro, should I have gone with a more forgiving bearing? I told my uncle to order me what bearings he thought'd do the best job for me (shift at 6500, he's an old dirt car racer, ran SBC's), and he said the H's would be good for this, but I've been told that they aren't very forgiving
 

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The "H" series Clevites are just a little harder and have a provision for a radius-ed crank journal. If anything, they're tougher. Why anyone would consider them '...less forgiving' I don't understand. Not to mention they're about twice the price of the "P" bearings.

You have excellent bearings.
 

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Good to hear, I was just worryin' myself.

As far as being more forgiving, someone told me that they need a better machining job and tighter tolerances than the P-series. Just everything needed to be a bit more "dead on". I'm not sure if the Scat crank is radiused or not (don't even know what "radiused" means when talking about a crank), but looking quick at their site here it says the 9000 cast series is modeled after their forged cranks, which are radiused. I was surprised how much they costed, but I figured since I don't have to pay markup it'd come out a wash, 'bout same as if I bought the cheaper bearings from Summit.
 

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You have the correct bearings. Since your crank is radiused you need to use the "h" series bearing.

The radius is the "bevel" at the edge of the journal that the rods ride on. You will see it at both edges front and back of all bearing journals. If you tried to run P-series pearings they would, dig into the radius. P-series bearings are slightly wider and not beveled. This would cause interference.


Royce
 

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The problem with the bearings being forgiving is with material embedding. The H bearings are much harder and do not like debris at all. P series is softer and will allow debris to embed in the bearing and become part of the surface, which most bearings are designed to do some what. Just keep it clean and plug the oil filter bypass if the engine has it so you dont send trash through the bearings.

Chris
 
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