How to groove a main bearing

[Krooser]

Alrighty...

I'll be using King pMax coated bearings in my SBM build. These Mopar's need some oiling help and there are mods and bandaids to help get eneough oil to the mains to keep the rod bearings safe. One of those is using a full groove bearing.

My King's are 1/2 groove. Using the pMax coated deal. Pricey little devils, too.

How sucessful have you guys been in machining a groove in a non-grooved bearing shell? I'm sure it has been done. I'd prefer not to use a Dremel if at all possible but I would not rule that out. I could practice on a couple used shells at first...

Let's hear it... BTW thanks again. It's really nice to be able to bouce these ideas off the heads of those who have been there-done that.

[BOOT]

idk the proper way to do it but if you use a dremel I suggest you tape the bearing to try n keep stuff from embedding in your clean bearing. Maybe use an old cap or block to rest it in. Cut/notch an old bearing to act as a guide & protect the new one? I'm just making WAG LOL

[Sparksalot]

I've done it many years ago using a purpose machined aluminum split housing fixture with the correct main bearing dimensions for the bore of the mains in the block. It was an analog for a main cap and the block. This was to achieve proper crush of the bearing halves and roundness of the shell ODs. I made plenty of clearance for the tangs to not interfere with the fixture bore, no precision needed as a bearing clamped in the correct bore will not move. The fixture could remain in the machine and have the cap removed and replaced to do multiple bearings.

The fixture was mounted to a faceplate with the bore centered to the spindle axis of a lathe and a cutting tool ground to the profile of the groove was used to make the groove. No risk or drama at all.

If I had to do it again I'd do the same thing.

[dannobee]

Easiest way to do it accurately would probably be to bolt two main caps together with the bearing halves in place, then chuck it up in the lathe and cut it.

[Ericnova]

I'd be worried that cutting a groove in the lower main inserts cuts their load carrying ability by half....that's the main problem with using full groove bearings in engines not designed for them.
Sure, now you have plenty of oil to the rods but fail the mains.

Maybe look at copying the Speed-Pro 3/4 groove main deal. Speed-Pro 120M for the Mopar LA engine

Some related discussions on load carry vs groove.
viewtopic.php?t=29638

https://www.enginebuildermag.com/2011/1 ... rformance/

[Geoff2]

Machining/grinding bearing shells raises the edge of the metal at the cut. How do you smooth &/or remove the raised surface & how can you be sure that enough has been removed so that there will be no steel-to-steel contact with the crank?

[BCjohnny]

To do it 'right' ...... split circular fixture that mimics the bearing housing bore

If full grove you can chuck it up in a lathe, if three quarter etc rotary table in a mill with appropriate cutter (thin 'tee slot' etc)

Some hand deburring would be expected regardless

Probably take longer to make the fixture than machine the parts, but that's the way it usually is

Not sure a Dremel will produce what you want repeatedly ..... except maybe expensive scrap

[ClassAct]

I'd be worried that cutting a groove in the lower main inserts cuts their load carrying ability by half....that's the main problem with using full groove bearings in engines not designed for them.
Sure, now you have plenty of oil to the rods but fail the mains.

Maybe look at copying the Speed-Pro 3/4 groove main deal. Speed-Pro 120M for the Mopar LA engine

Some related discussions on load carry vs groove.
viewtopic.php?t=29638

https://www.enginebuildermag.com/2011/1 ... rformance/

To live he needs oil to the rods full time. It’s not a Chevrolet. I have yet to see a single main bearings that was fully grooved show any signs that the bearing lost any load carrying capability. Never seen a main bearing fail because they had a full groove.

[Circlotron]

I have yet to see a single main bearings that was fully grooved show any signs that the bearing lost any load carrying capability.

Not my area of expertise, so shoot me down if necessary, but I think of grooved bearing like a grooved tyre in the wet. Makes it easier to cut through the liquid film and make hard contact.

[cncguy987]

Nascar blocks groove the block and they add extra holes for oiling purposes.

[Krooser]

Thanks... I'm trying to avoid the disaster that is the reason for this engine to be redone... lack of oil to the front rod journal at higher rpm.

The SBM oils the lifters before the main bearings. Not so good at 7G.

I'm hoping the pMax coating helps a bit.

I'll have to talk to my machinist soon.

[C.A.R.E.]

I have made some plain non groved lower main bearings into a 3/4 type by surfacing the side a main cap so it clamps on my Bridgeport with the bearing surface 90* to the table. I then used some bolts, nuts, flat washers, to clamp the bearing in place. Used a 2.5" diameter ( this was a SBC )3/16 thick circular splitting saw and a R8 mandrel in the column, position, cut and deburr with bearing knife. Leave cap clamped and just change bearing. Worked great and fast ! This can also make full grove lower mains.

[67satellite]

Have you run the tube from rear passenger side to front driver side oil galley? That is supposed to supply more oil to the front.https://www.forcbodiesonly.com/mopar-fo ... ods.55518/ Scroll down midway in the post for pics.

[pamotorman]

4 cylinder chevy engines had the same problem and what i did was feed the main oil gallery from both ends using a remote oil filter with 2 outlets.

[Paul Kane]

...These Mopar's need some oiling help and there are mods and bandaids to help get eneough oil to the mains to keep the rod bearings safe. One of those is using a full groove bearing.

My King's are 1/2 groove...

How sucessful have you guys been in machining a groove in a non-grooved bearing shell?

Let's hear it... BTW thanks again. It's really nice to be able to bouce these ideas off the heads of those who have been there-done that.

There are two primary ways to to get 360-degree oiling from a half-groove main bearing:

1) In the 1960's Top Fuel hit a wall of sorts in that the fastest guys started repeatedly kicking their rods out of the pan of their Nitro engines because of inadequate rod bearing oiling due to the available bearings of the time. The fix that most teams did back then was to put the crankshaft into a lathe and groove the mains, thereby creating 360-degree pressurized oiling to the rods (ie, akin to a full-groove bearing, in effect). The engines then stayed together and the cars got faster.

2) If you prefer to set your block up with full-groove main bearings but no-one makes them, then you can buy two sets of half-groove mains, install the upper shells from Box #1 in to the upper main saddles of the block, and then install the upper shells from Box #2 into the lower main caps. In order fit an upper shell into a lower main cap, simply cut an upper shell bearing tang receiver groove into the lower main cap. Like this:

FullGroove01.JPG

In the above photo, the factory original bearing tang groove (for the lower shell) is on the right, and using a Keyway Cutter I've just added the new bearing tang groove (for the upper shell) on the left. The newer tang groove accommodates the upper shell thereby making a full-groove bearing. The picture below shows the upper shell installed into the lower main cap:

FullGroove02.JPG

This is what we have to do now since Mahle bought Clevite and eliminated the Ford 429-460 full-groove main bearing. We have successfully used this setup in Blown Alcohol and Blown Nitro (70%) engines past 200 MPH in the Quarter Mile