426 hemi main bearings

[gtx446]

Need some help.My engine builder is building a 426 Hemi. He is looking for partial groove main bearings,20 under and tri metal. Anyone out there have any or do you know where i can locate them? Any info would be appreciated. Thx vic

 

[69Bee]

EVERYTHING crosses to a std RB bearing; MS-877P-20. They match your criteria (TM77, 0.020"OS) with the exception that they are fully grooved. The only available bearings that are partial grooved stop at 0.010"OS. Use the 877 set, and a HV oil pump. Summit has a good price of $81.97 plus shipping.

 

[lewtot184]

to my knowledge there isn't a tri-metal half groove bearing. there is a bi-metal half groove, 4924M. the original hemi and s/s wedges had a wide full grove tri-metal bearing which i think is obsolete. the 877P bearing is a narrow full groove tri-metal bearing which has taken the place of the wide groove and the bearing i'd recommend if your going to make some power. the hemi's and s/s wedges also had a tri-metal rod bearing, cb665p, that had about .0005"-.001" more clearance but i think it's obsolete also. use the cb527p for the rods. i consider the full groove/partial groove argument to be more of addressing a small block chevy problem than a chrysler problem. but, chrysler and ford folks have always taken ownership of chevy problems for some odd reason.

 

[rev.ronnie]

Crower 85430C main bearings come in .010"-.030" undersizes I believe.

 

[snakeoil24]

Rev. Ronnie knows his hemi's. The crower people have the product your looking for. if you can't get the bears please pm me I do have a source. The hemi needs the wider play of the bigger bearing. These are not wedge motors, remember the extra Power capabilities of the hemis demand the extra quality and stout of the bigger bearings. Divorce your thinking about Wedges and Hemi's they don't mix well and demands are 30 percent more demanding. if Crower can not help call Diamond Piston or Crane and ask them for their contact with the custom bearing people.

 

[68 HEMI GTS]

from the sounds of that post you need a new hemi engine builder. :icon_frown:

 

[lewtot184]

from the sounds of that post you need a new hemi engine builder. :icon_frown:

amen

 

[Hemirunner]

Be careful with the 877P. It will interfere with the radius on the crank. I normally run clevite MS2233HG mains but I think the smallest they come in is .010 under. These are a 3/4 groove bearing which maximizes support without sacrificing oiling.

 

[68 Sport Satellite]

Meeps should chime in here. He knows his way around a Hemi...

 

[gtx446]

thank you all for your responses.I appreciate it..thx Vic

 

[Garys1969RR]

I have a question on these main bearings. Does the Hemi need a half groove bearing because the downward loads (lower half of bearing) are heavier on a hemi? So without the groove in it, you have a little more bearing area to carry the higher loads?

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I usually use the fully grooved main bearings on the wedge engines, for increased rod bearing oiling. Never had a problem with either type. Seems like the old Direct Connection manuals recommended this. Of course the Hemi generally produces more torque/horse power, and has different requirements.

 

[rev.ronnie]

The non-grooved lower has a better load carrying surface. I think the groove tends to become a hydraulic "leak" so-to-speak. Full groove bearings and a cross drilled crank are a recipe for disaster.

A note on cross drilled cranks.
-------------------------------------
I won't run a cross drilled crank in anything other than a low rpm diesel. On automotive cranks, I actually plug them if they are drilled. I use 1/4" dowels if they fit tight, or make my own if they need to be bigger.
396/427 Chevys are notorious for being cross drilled from GM...I plug them. My 426 Hemi crank was too. I plugged that one as well. At high RPM, the rods will starve the mains if they are cross drilled, from the centrifugal forces. You won't find a true performance crank that is cross drilled.

The 3/4 groove bearings address the connecting rod oiling very well and still carry load...best of both worlds.

I treat all the BB mopars the same, Hemi or wedge. Now that the wedge engines are making the same rediculous power as the Hemi's, you have to treat them as the same. Modern cylinder heads have closed the gap on the two engine designs.

 

[Meep-Meep]

I have the narrow full groove mains in my 440 and from what I was told those are a 413 truck bearing.

From what I can see it's either the cross drill and half groove or no cross drill and full groove. Either one will get you the same result. It's all about 100% duty cycle oiling to the rods. A buddy races Mazda Miatas and those are cross drilled cranks with half groove bearings. I'm pretty sure 427 Fords used to groove the crank.

 

[rev.ronnie]

The thing with the import engines and cross drilled cranks, is that they run extremely tight bearing clearances and small journals. A 1.88" Honda pin with .0014" clearance won't pull the oil off the mains nearly as bad. There just isn't the volume....and nowhere near the stroke as a big ol' V8 The journal speed is pretty slow in a 3" stroke engine compared to a 4.25" at 7500 rpm. The little 4 banger would have to spin just under 10,000 to have the same journal velocity.

 

[Meep-Meep]

Yeah, those cranks are like toys! Miata boy hasn't blown anything up so something is working out well.

So you say even if you run a cross drilled crank with half grooved bearings there will be a problem at high RPM?

 

[rev.ronnie]

Yeah, those cranks are like toys! Miata boy hasn't blown anything up so something is working out well.

So you say even if you run a cross drilled crank with half grooved bearings there will be a problem at high RPM?

Yes, I think it's still detrimental. The centrifugal force is one issue. The rods want to siphon the oil off the mains. Another issue can be when the main hole is lined up with the the cross drilled hole, it now provides an escape path...I can't help but wonder if the oil may actually be blown past the rod hole to the path of least resistance.

I just know that no manufacturer does it anymore for a number of reasons. Weakening of the actual main journal is probably a big concern too. Now that most performance cranks are rifle drilled for strength, cross drilling is an impossibility.