when are 3/4 grooved main bearings needed for bbc ?

[Warp Speed]

Why do LS engines use a shorter (less than 180*) main bearing groove?
Why do they use a 180* on the thrust only?!?

[RCJ]

180 on the thrust, so all the oil bleeding off at the parting line can oil the thrust?
If you were trying to reduce the amount of oil required by the rods, would coatings on the bearing or journal be of any benefit?

[ClassAct]

If I recall right reason 360 main bearings got used in the hemi had more to do with oiling the 4 shaft system, but they do sometimes recommend using them in the rb 440 wedge builds. Obviously the hemi had plenty enough oil wedge for heavy loading and power. Pretty silly for anyone to think 1 type of bearing works best for all engines. If 180 bearings were that proven to be that good there would be no one manufacturing different groove length bearings.


..

That reasoning you use, really relates to old Mopar Performance books of the past century. There are many, more efficient ways to cure problems these days. It is best to properly address one problem at the root cause, than it is to band aide it. By applying these band aides, as you suggest, creates a whole nother set of problems.

Warp, other than a mechanical fix of oil timing, which is the root cause, how do you correct oil timing. I know you understand it. And I know that we both know what happens when full groove bearings are used, but again, other than a mechanical fix, how do you correct oil timing?

You can live with the results of full time Rod oiling, or you can kick the rods out? If those are your options, which do you choose? I'd love to hear how you mechanically fix an oil timing issue. And is not just th Chrysler junk that has junk oil timing. It's Buick, Pontiac, Olds, Fords. Some of us still deal with this.

Waiting to hear your thoughts.

[ptuomov]

Nothing really wrong with it, especially for a restoration build. But as I have stated, there is no need to use the fixes (band aides) of the past to be successful.

It's all band-aiding to some extent when you're modifying an existing engine. So what are the relative merits and demerits of either 360 grooving the main bearings or cross-drilling the rod journals in this sort of a setup? With cross-driller rod journals, there's almost always some clearance that can fit more oil in the rod bearing.

[Warp Speed]

180 on the thrust, so all the oil bleeding off at the parting line can oil the thrust?
If you were trying to reduce the amount of oil required by the rods, would coatings on the bearing or journal be of any benefit?

Exactly on the bleed off part oiling the thrust.
This bleed at the parting lines actually decreases the pressure in the groove, and subsequently, the flow to the rods. So while a longer groove can increase the time the rod is fed, it also, in most all cases, reduces the actual flow to the rod due to this bleed at the parting lines.

[Warp Speed]

If I recall right reason 360 main bearings got used in the hemi had more to do with oiling the 4 shaft system, but they do sometimes recommend using them in the rb 440 wedge builds. Obviously the hemi had plenty enough oil wedge for heavy loading and power. Pretty silly for anyone to think 1 type of bearing works best for all engines. If 180 bearings were that proven to be that good there would be no one manufacturing different groove length bearings.


..

That reasoning you use, really relates to old Mopar Performance books of the past century. There are many, more efficient ways to cure problems these days. It is best to properly address one problem at the root cause, than it is to band aide it. By applying these band aides, as you suggest, creates a whole nother set of problems.

Warp, other than a mechanical fix of oil timing, which is the root cause, how do you correct oil timing. I know you understand it. And I know that we both know what happens when full groove bearings are used, but again, other than a mechanical fix, how do you correct oil timing?

You can live with the results of full time Rod oiling, or you can kick the rods out? If those are your options, which do you choose? I'd love to hear how you mechanically fix an oil timing issue. And is not just th Chrysler junk that has junk oil timing. It's Buick, Pontiac, Olds, Fords. Some of us still deal with this.

Waiting to hear your thoughts.

I'd try NOT using a 50 year old crank, and its inherent flaws, in a performance engine! Lol
Who is really going to be hammering on a true restoration, and if not for correct restoration purposes, why continue the mess in the first place?!?

[digger]

180 on the thrust, so all the oil bleeding off at the parting line can oil the thrust?
If you were trying to reduce the amount of oil required by the rods, would coatings on the bearing or journal be of any benefit?

Exactly on the bleed off part oiling the thrust.
This bleed at the parting lines actually decreases the pressure in the groove, and subsequently, the flow to the rods. So while a longer groove can increase the time the rod is fed, it also, in most all cases, reduces the actual flow to the rod due to this bleed at the parting lines.

are you saying the 360 groove on main increases flow out the part lines taking it away from rods ?

[Warp Speed]

180 on the thrust, so all the oil bleeding off at the parting line can oil the thrust?
If you were trying to reduce the amount of oil required by the rods, would coatings on the bearing or journal be of any benefit?

Exactly on the bleed off part oiling the thrust.
This bleed at the parting lines actually decreases the pressure in the groove, and subsequently, the flow to the rods. So while a longer groove can increase the time the rod is fed, it also, in most all cases, reduces the actual flow to the rod due to this bleed at the parting lines.

are you saying the 360 groove on main increases flow out the part lines taking it away from rods ?

Yep.

Say you got .0035 main clearance. What is it at the parting line? Probably .006-.007. Oil will take the path of least resistance. So now, you have GREATLY increased the flow through the engine, but very little of your increase, if any at all, is going anywhere important like the rod bearings.
Same thing with increasing main bearing clearance.

[ClassAct]

That reasoning you use, really relates to old Mopar Performance books of the past century. There are many, more efficient ways to cure problems these days. It is best to properly address one problem at the root cause, than it is to band aide it. By applying these band aides, as you suggest, creates a whole nother set of problems.

Warp, other than a mechanical fix of oil timing, which is the root cause, how do you correct oil timing. I know you understand it. And I know that we both know what happens when full groove bearings are used, but again, other than a mechanical fix, how do you correct oil timing?

You can live with the results of full time Rod oiling, or you can kick the rods out? If those are your options, which do you choose? I'd love to hear how you mechanically fix an oil timing issue. And is not just th Chrysler junk that has junk oil timing. It's Buick, Pontiac, Olds, Fords. Some of us still deal with this.

Waiting to hear your thoughts.

I'd try NOT using a 50 year old crank, and its inherent flaws, in a performance engine! Lol
Who is really going to be hammering on a true restoration, and if not for correct restoration purposes, why continue the mess in the first place?!?

What if it's not the crank? What if it's a relatively new aftermarket block? Again, I'm asking you the same thing...how would YOU fix an oil timing issue.

Again...waiting....

[Little Mouse]

Exactly on the bleed off part oiling the thrust.
This bleed at the parting lines actually decreases the pressure in the groove, and subsequently, the flow to the rods. So while a longer groove can increase the time the rod is fed, it also, in most all cases, reduces the actual flow to the rod due to this bleed at the parting lines.

are you saying the 360 groove on main increases flow out the part lines taking it away from rods ?

Yep.

Say you got .0035 main clearance. What is it at the parting line? Probably .006-.007. Oil will take the path of least resistance. So now, you have GREATLY increased the flow through the engine, but very little of your increase, if any at all, is going anywhere important like the rod bearings.
Same thing with increasing main bearing clearance.

Your not supposed to know these things lol. Ya about 30 percent more flow 70 percent loss so they say. Hell I'm going to need all kinds of oil thrown around help lubes my flat tappet cam, who cares about power lol. Wont really be using 360 bearings crank I have to use claims they cross drill them.

[Little Mouse]

are you saying the 360 groove on main increases flow out the part lines taking it away from rods ?

Yep.

Say you got .0035 main clearance. What is it at the parting line? Probably .006-.007. Oil will take the path of least resistance. So now, you have GREATLY increased the flow through the engine, but very little of your increase, if any at all, is going anywhere important like the rod bearings.
Same thing with increasing main bearing clearance.

Your not supposed to know these things lol. Ya about 30 percent more flow 70 percent loss so they say. Hell I'm going to need all kinds of oil thrown around help lubes my flat tappet cam, who cares about power lol. Naw not really going to the el cheapo only one that makes cheap in 3.25 forged is eagle and they say they use cross drilling no use for any 360 bearing.

[digger]

Exactly on the bleed off part oiling the thrust.
This bleed at the parting lines actually decreases the pressure in the groove, and subsequently, the flow to the rods. So while a longer groove can increase the time the rod is fed, it also, in most all cases, reduces the actual flow to the rod due to this bleed at the parting lines.

are you saying the 360 groove on main increases flow out the part lines taking it away from rods ?

Yep.

Say you got .0035 main clearance. What is it at the parting line? Probably .006-.007. Oil will take the path of least resistance. So now, you have GREATLY increased the flow through the engine, but very little of your increase, if any at all, is going anywhere important like the rod bearings.
Same thing with increasing main bearing clearance.

i'm not seeing how the full groove affects the flow out drastically maybe i'm thinking about it wrong , i can see if you increase the main clearance the oil will leak out more as least resistance but the full groove seems like it would have a relatively 2nd order effect on lowering overall resistance to leakage

[Warp Speed]

are you saying the 360 groove on main increases flow out the part lines taking it away from rods ?

Yep.

Say you got .0035 main clearance. What is it at the parting line? Probably .006-.007. Oil will take the path of least resistance. So now, you have GREATLY increased the flow through the engine, but very little of your increase, if any at all, is going anywhere important like the rod bearings.
Same thing with increasing main bearing clearance.

Your not supposed to know these things lol. Ya about 30 percent more flow 70 percent loss so they say. Hell I'm going to need all kinds of oil thrown around help lubes my flat tappet cam, who cares about power lol.

If that, depending on rpm and crank design, when you probably could have gotten the same increase by just jacking the pressure real high. Centrifugal forces to be considered here.

[Warp Speed]

Warp, other than a mechanical fix of oil timing, which is the root cause, how do you correct oil timing. I know you understand it. And I know that we both know what happens when full groove bearings are used, but again, other than a mechanical fix, how do you correct oil timing?

You can live with the results of full time Rod oiling, or you can kick the rods out? If those are your options, which do you choose? I'd love to hear how you mechanically fix an oil timing issue. And is not just th Chrysler junk that has junk oil timing. It's Buick, Pontiac, Olds, Fords. Some of us still deal with this.

Waiting to hear your thoughts.

I'd try NOT using a 50 year old crank, and its inherent flaws, in a performance engine! Lol
Who is really going to be hammering on a true restoration, and if not for correct restoration purposes, why continue the mess in the first place?!?

What if it's not the crank? What if it's a relatively new aftermarket block? Again, I'm asking you the same thing...how would YOU fix an oil timing issue.

Again...waiting....

You're gonna have to be a little more precise than that, and I would be glad to help. But if your just gonna be an ass, keep waiting!
Btw, how does a block effect oil timing?!?

[Warp Speed]

are you saying the 360 groove on main increases flow out the part lines taking it away from rods ?

Yep.

Say you got .0035 main clearance. What is it at the parting line? Probably .006-.007. Oil will take the path of least resistance. So now, you have GREATLY increased the flow through the engine, but very little of your increase, if any at all, is going anywhere important like the rod bearings.
Same thing with increasing main bearing clearance.

i'm not seeing how the full groove affects the flow out drastically maybe i'm thinking about it wrong , i can see if you increase the main clearance the oil will leak out more as least resistance but the full groove seems like it would have a relatively 2nd order effect on lowering overall resistance to leakage

The parting line has the most clearance. But any clearance at a pressurized area leaks. Now you have a 360* leak path, which in essence doubles it.