Full Groove vs. 3/4 Groove Mains for BB Mopar

According to Mahle-Aftermarket's documentation, 3/4 groove bearings promote less HP loss and don't suffer any lubrication loss vs. Full Groove bearings.

Is there any reason to not use 3/4 groove bearings in a BB Mopar stroker engine? Or any better reason(s) to use Full Groove instead of the 3/4-groove?

I have a pretty good reason for not using 3/4 groove in my BB.

400 Mains.

That being said, the regular ol 876P full groove bearings I am replacing in my engine were put in it in 2018, and I could reused the rod bearings if I wanted to at 800+ hp.

And they have a LOT of passes on them. Like 200 a year except for covid year when I only put 110 on it.

Man, that's awesome! Glad they held up that well for you!

Yeah, guess I should have said RB based stroker...

Do you want oil pressure to your rods full time or not?
I do , I use the ruck narrow full groove main bearings, not the wide full groove race bearings

Oil does two things in our motors, lubricate and cool, I like cool cranks

Are those the same as the MS-1277HG Clevite 77's?

I can't answer that sorry. I use to use the Seal Power part number M4500 for the RB motors and their M4400 for the B motors, I think they discontinued the M 4400 several years back
I prefer to build the 400 blocks over the 440 blocks due to the thicker main webbing

Ok, I get ya. I think they are the same bearing. I have a '78 440 and I think it is similar to the 400's in that respect.

I use 3/4 groove if I can find them. Sometimes it is really hard to find bearings these days so you just live with what you can get. In the old days when parts were available we used 3/4 groove on everything.

I like the Speed Pro 119M 3/4-groove main (although they're really more like a 5/8 with a wide groove if you look closely). That said, I wouldn't think twice about running a traditional full-groove, which I have in the past. I know Cab is a big proponent of the narrow-type full-groove and I'd consider those if I couldn't get my preferred 119Ms.

I was just commenting for the sake of the full groove 3/4 groove debate.

I would probably run a 3/4 groove if it was an option but it isn't.

And I never had any problems I could link to full.

I've run Clevite 3/4 groove in my 4.5 stroke motor to 7200. 11 years 1000 passes. They've been fine

Here is the info from Clevite with the attached Graphs

Iget it, but what about the the effects on the rod bearing.

I know that the 1/2 grove is best for the main wedge/film but I more concerned about the rod.

Yep, that's the info I was referring to. Good research on their part.

That is the way I am going. The 3/4 groove set wound up fitting much better across all of the mains than the full groove set did.

Thanks for all the replies, all!

So what are people opinions of 3/4 groove Speed pro 119M vs. Clevite MS-2233HG ?

Also, Has anyone ever measured bearing eccentricity ? I'm dial boring my engine bearings now to calculate clearance and don't know what to expect.

AG.

Bearings can be hard to find these days so you should feel lucky that you have a couple of sets to pick from.

If both of them fit (meaning no interference with the radius or the block) I would run the ones that gave me closest to the clearance I wanted.

I like the 119m .....they are typically cheaper.

I don't think we are supposed to think about eccentricity. I don't believe we know anything about that nor is it something we can change. I think our job is to make sure the hole is the right size (2.9425"-2.943") and that we have the proper bearing
to crankshaft clearance in the vertical dimension.

It use to be the standard on the rod bearing being wider, more oil clearance at the rod joint to allow a build up of oil to, (puddle) help lubricate the bearings better as the rod rotated on the cranks
I'm thinking between .0003 to .0005 additional clearance

On the 119M mains I'm seeing about .002" eccentricity and consistent from hole to hole and the housing bores are perfect so I know its in the bearings.
AG.

Is that a bad thing? What is your vertical clearance?

I don't have a crank to calculate actual clearance but If I get a crank at nominal diameter than clearance will be .0025-.003( .003 on the center thrust main) . If I base it on the last K1 crank I had(main journals were slightly below min spec) than my clearance will be .0035-.004 (.004 on the center thrust main).
I had a set of full groove Clevite 877P bearings and mounted one in the #1 main to spot check and was pretty much the same.

AG.

I've noticed the same thing, any idea why?

Taken from the Cleveite bearing catalogue

“The wall is thickest at 90 degrees from the split and drops off a prescribed amount toward each parting line, depending on the bearings intended application. This drop off is called “Eccentricity.” In addition, there is a relief at the parting lines. Eccentricity is used to tailor the bearing shell to its mating hardware and to provide for hardware deflections in operation. Eccentricity also helps to promote oil film formation by providing a wedge shape in the clearance space. The relief at each parting line insures that there will not be a step at the split line due to bearing cap shift or the mating of bearing shells that differ slightly in thickness within allowed tolerance limits”
Its a good read if you want to know bearing specifics..

Thanks but I have already read it and well aware that there is eccentricity built in but was hoping the catalogs would have more specific informataion than just low/medium/high ecentricity....
AG.

The same old story, global supply chain issues..... The middle east is in turmoil and King bearings is in Jerusalem from what I understand.

I was in contact with king on there +/- ,001 race main bearing sets and they tell me the production date is scheduled for 8/24.

AG/