Finally got my hands on an unused, never bored megablock.Had it crack checked ,bored to 4.350",line honed & studded.Looking for bearing experiences,as Iam in the middle of pre-assembly for clearancing and deck height check.
Parts include,Cam Motion .690" 280*/283* @.050 roller,Victor monster-maxwedge heads and intake w/dominator,Source 4.150 crank,BME aluminum rods w/std big end,Milodon dual line system w,dragster style pan.Goal is to Heads-up index race. Has 13.5-1 diamond pistons and will get 200 hp nitrous if necessary. All opinions and experiences wellcome.THANKS ALL, Bill

king hp

Same thing I bought for my mega block

On the mains I would, and do, use the Federal Mogul truck narrow full groove #4500M, Clevite narrow full groove MS-1277HG or the newer part # MS-2324P
on the rod bearings with the aluminum rods I would probably use the Clevite 527HD or what ever rod bearing part numbers BME recommends
IHTHs

Thanks guys,anyone have experience with MS 2233HG 3/4 groove main set? Forgot to mention it does not have pushrod oiling system. I greatly appreciate the feedback. Bill

The King hp are great, and they are 1/2 groove. For 30 years I ran full groove, even made my own jig for full grooving oversize bearings. Always seemed to be getting a rod bearing within 50-75 runs. Last build 5 years ago my machinist guy who builds T/D and T/S monster motors suggested getting away from full groove. I thought what I'm doing isn't holding up, lets try it. Now this was a 4.75 stroke cut .030/.020 with 2.200 rod journals. The motor lived without incident until it dropped a valve after 200 plus runs. The bearings were still excellent. No more full grooves for me. Sometimes you have to get out of the box. I run 10-40 royal purple with the Milodon swinger, and sometimes the pressure would go to zero under hard braking. The bearings showed NO signs of distress. I put a stop in the pan to keep the PU from going all the way forward. I spoke to the guy that designed them years ago, and he sez they suck. I think he's right, but I'm still running it.
RIP

Why wouldn't you listen to the motor when it was saying it needed oil pressure all the time? The lack of oil, even in Nano seconds, will kill any bearings loaded hard enough
Have you looked at the width and depth of the stock Hemi full groove main bearings versus the Clevite 877P main bearings or the Federal Mogul main bearings I listed? If not maybe you should
As far as monster motors most of the top alcohol motors get towed every where they go until they start them up behind the burn out box, they also shift them at or above 11,000 RPM don't they The majority of Top Dragster motors I see are aluminum BB Chevy motors, aren't they
Both of those worlds are places I don't want to go to
Way to much maintenance with not enough fun to justify the effort needed to do that

? I've read your piece 3 times. I have no clue what your point is. I merely stated my experience and opinion. If you need to "win" the conversation, cool by me. The fact that I lost oil pressure doesn't mean I didn't address it. Only that it did happen. The basic method of supplying oil to bearings through the crank hasn't changed in @ 80 years. I have a KB block and an Indy block. I also run a 565 Chevy in another car. Spun bearings happen to all brands. Why should a modern race block with priority oiling need full grooves?

I've come to believe that full groove is a poor crutch for tight clearances and too thick oil. You see all the new HO engines from A-Z making insane power, running thin oil, and half groove bearings.
Throwing jabs at other brands doesn't work for me.
This is a place where we can present our opinions and experiences for all to consider.

I left junior high a LONG time ago.

Just something to think about in bearing grooves. The idea is to create an oil wedge as wide, and stable as possible. The crank is always trying to exit the motor out the bottom. So the wedge is on the bottom bearing as the clearance is mostly on the top bearing. The outer edges of the bottom bearing are losing the wedge as the oil runs off them. The greatest opportunity for the wedge to overcome forces is in the center of the bottom bearing. Cutting it in two reduces the amount of protective wedge you have. The oil pressure in the groove does nothing to support the crank, and increases the load on the two narrow surfaces.

King HPs also have taper from the center out to the sides to deal with crank flex and promote the safest wedge I've personally seen in the type engine we're talking about. Given we're running normal oil viscosity, and need real bearing clearance. I wouldn't run them in some PS type 0 weight application. I would however, not run any full grove bearing in something I was going to make power with.

I've seen more before, and after experiments with bearings than I can recall. I've never seen a full groove protect, last, or be nicer to the crank than solid bottoms. No disrespect to anyone that runs them JMO.

I find this interesting and informative, ive been hooked on King for nearly 10 years and even on some run the extra .0005 on the rear main as they suggest on some applications.

In our pull tractor all we use are King HP 3/4 (seems more like 5/8) bearings, never a bearing issue

Oddly for the first time in 35 years I just used a set of full groove mains on a semi mild small block going on the thought of more full time oiling. I did it because I used a big hydro cam that in the end will probably prove to be more of a hastle then just running a mild solid but Im thinking with a hv pump I can keep good oil to the lifters and rods.

Im not worried on the load issues with such a mild build on the mains and honestly its as simple as it gets but im out of my comfort zone because I dont use full groove mains or hydro cams so it should be interesting.

In the end I think most use what works best for them in there application, I think Cab is old school smart and if hes using full groove mains and they work for his application thats great because really alot of use use the same basic parts its only the application and build techniques that differ.

In a very interesting note--King used to supply many part numbers in a 3/4 groove--long thought to be the best of both worlds--so when I ordered some to replace a set in a customers engine I was told they no longer produced them--I called Kings tech and they said flat out--the half grooves have proven to be the best answer and that was the way they were going with lots of applications I personally have never had any bearing issues with a Mopar- full groove, half, narrow, wide--whatever -guess I have never been hard enough on one LOL

I also had issues with oil pressure, once running through the traps with only 45 psi at 7500 rpm in a 4.15 stroke full size bearing bottom end. I run King, FM, bearings 1\2 Grove and have run 3\4 Grove. I was surprised to see so little damage, and had two minor issues on a couple of rod bearings, the mains looked great. If enough oil is going through the journal for cooling, I believe the extra surface area of a 1\2 or3\4 Grove is a help in providing life in case of momentary oil pressure loss.
Before I came up with a good oil pan and accusump, I really had to watch how hard I hit the brakes, and more than a few times I am certain I ran a lot of air through the oiling system! Never any full fledged bearing failures, just a very slight amount of damage, not enough to make them fail.

Being a engine builder and a long time drag racer the reason I advocate and use full groove main bearings on all of my HP engine builds for B,RB and all hemi motors is that I like the rods to have oil pressure during 360 degrees of crankshaft rotation, not just 180 degree that the single upper groove main bearings provide.
Think about the hole in the crankshaft from the main bearings to the rod journals and when the rods are getting oil pressure and where is the most load on the bearings and rods, it is not in the bottom half of the stroke
To many people, races and others, believe what they hear from "experts or what they read from some expert" in print, not what they have actual real world experiences from
My first rod bearing failure(when I was 19 yrs old) was due to me running my go to work daily driver to low on oil many years ago I got lucky and had it fixed before it spun, it rolled a piece of the center of one rod bearing up and staring knocking and didn't spin
The mechanic showed me that bearing and explained what he thought had happened, that was a true blessing that helped me start to understand why things got hurt and failed.
Racing motor engine bearings normally fail do to a lack of adequate oil supply or to much air in the oil
Take a look at NASCAR and road racing engines that live for hundred of laps at or above 7500 RPM, Formula One motors revved way past 15,000 RPM is what I have heard on T.V broadcast and they live for the entire race.
My Son worked for Rob Muzzy for many years in his production shop, I was privileged to be able to talk to Rob and his main racing mechanics about the RPM and the details that they had to discover to make their motors live long enough to win world championship in motor cycle racing.
All parts that fail under racing conditions for one racer or one team that are living in other racing engines in the same class are failing do to ignorance or failure to learn why those parts are failing and correcting the problem
Good luck to all those that push their racing parts to their limits
I don't do that

http://www.mahle-aftermarket.com/media/l...gs/eb-40-16.pdf

Go to page 19 for main bearings. My engine guy has moved to the half groove style and prefers the 140° groove where available.

"In an effort to develop the best possible main
bearing designs for performance engines, we’ve
investigated the effects of main bearing grooving
on bearing performance. The graphs illustrate
that a simple 180 degree groove in the upper
main shell is still the best overall design.
While a slightly shorter groove of 140 degrees
provides a marginal gain, most of the benefit
is to the upper shell, which doesn’t need
improvement. On the other hand, extending
the groove into the lower half, even as little as
20 degrees at each parting line (220 degrees
in total), takes away from upper bearing
performance without providing any benefit to
the lower half. It’s also interesting to note that as
groove length increases so do horsepower loss
and peak oil film pressure which is transmitted
directly to the bearing."

142M have worked great for street and strip for years, always come out looking good and handles the HP just fine.

I use Calico Bearings because they are Clevite HP coated bearings.

Thanks for all the great input.Am on this site a couple of times a day, most days. Very informative.On this topic, King bearings seems to be a favorite. Having no experience with them, I called the company.As suggested here,they too,recommended their HP series bearings for the megablock mains and aluminum rods.This motor is going to spin between 7200 &7500 rpms.They are listed as bi-metal bearings and my understanding is that they are somewhat harder surface than the Clevite tri metals.King also suggested they would be a better choice than the XPs for my application. am trying to wrap my head around all this. Chances are that it will more than likely see a MAX of 200 horses of nitrous,too. Any help? thanks, Bill

In terms of damage, are companies and users talking about simple damage to the bearings/crank/rods vs the added oiling or lack of constant oiling that 360 grooved bearings provide?