LB7: Daily Driver/Tow Rig Rebuild

[PureHybrid]

Don’t know as this is the first time I’ve done it. Don’t have enough miles on the setup to be able to tell you that it holds, only about 5k miles, but they’re hard ones. I purely went by what the machine shop told me, which was that it’s done on gassers all the time. I guess time will tell.


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And IIRC correctly a reputable builder told you that also

 

[gmc502]

I split the bearings on my offshore boat engines,,700hp,900tq whippled big blocks,spin to 6000rpms,,been that way for 12yrs of some real abuse.
I even had to take a razor blade(brand new and scotch brighted after) to one set because the eagle crank was cut/polished to the high side on one journal.(wasn't waiting on machine shop).I don't recommend it but it worked out for me.someday I'll have the crank fixed right,still waiting.

 

[Chevy1925]

God damn... I’ll have to apologize Pure. You are right. I shoulda went out there first and verified between the bearings...

Sorry guys, I really f**ked up in my posts here. Clearly my ass is jumping the gun waaaay too much lately.

 

[rcr1978]

All sounds good, but bearings aren't round to begin with. I don't have a pair of H/HX bearings to measure, but I would venture to bet the thickness of the bearing shell in the crush zone is the same.

I about shit the first time I measured some main bearings with a dial bore gauge and thought man those are not round at all

If I remember right mine were .0015"+ larger in the 3&9 O clock postions vs the 12&6.

 

[rcr1978]

I also shit when I measured my cylinders fresh back from the machine shop with the dial bore gauge, I was going to send it back .

Well put a torque plate on it and to my surprise it was almost perfect .

Now on I will never stud a engine without being machined with torque plate/studs or align hone after seeing how much the cylinders and mains move with the different fasteners.

 

[Chevy1925]

Even in the off set idea, I’d say main 1-3 is .0025 and main 4 is .0020, then 5 is back to .0025 (never is that perfect but let’s pretend). If you throw a hx half on the bottom side of 4, your up to .0025 but the off set is really just .00025 clearance difference between mains 3 and 4 once the crank centers up. Which if the bearings can be swapped around right to keep that off set small, it would be a non issue. I’d just keep the larger clearance on the main cap since the bottom bearing sees the most load.

Rods probably won’t care but I’d try to make the off set the same on rod pairs just for ocd reasons and keep thrust surfaces on the same plane but again, probably won’t make a huge difference.

 

[M.A.M.]

And IIRC correctly a reputable builder told you that also

Yep, they’ve been racing for over 30 years.

Mahle specifically states that bearings have to be measured 90° from the split since that’s the thickest point. The bearings taper down and are actually a bit wedge shaped at the split.


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[Chevy1925]

I also shit when I measured my cylinders fresh back from the machine shop with the dial bore gauge, I was going to send it back .

Well put a torque plate on it and to my surprise it was almost perfect .

Now on I will never stud a engine without being machined with torque plate/studs or align hone after seeing how much the cylinders and mains move with the different fasteners.

Absolutely. Quite the massive difference and even the torque from 125 to 150 can make a measurable difference.

 

[Chevy1925]

Yep, they’ve been racing for over 30 years.

Mahle specifically states that bearings have to be measured 90° from the split since that’s the thickest point. The bearings taper down and are actually a bit wedge shaped at the split.


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You guys can quit hiding that it was SoCal Diesel that said it. I’ll even post the thread lol.

https://www.duramaxdiesels.com/forum/showthread.php?t=78533

Regardless of the taper, my concern was there was still .0005 thicker at the ends of the taper on a H vs a HX. Not the case. I was wrong there

 

[Bdsankey]

GM mismatches bearings all the time, I bet your current motor has different top/bottom rod bearings and possibly some on the main bearings if its stock.

You guys can quit hiding that it was SoCal Diesel that said it. I’ll even post the thread lol.

https://www.duramaxdiesels.com/forum/showthread.php?t=78533

Regardless of the taper, my concern was there was still .0005 thicker at the ends of the taper on a H vs a HX. Not the case. I was wrong there

So if this is acceptable, RCR1978 shoot me a text on those bearings. 906-284-0962.


This thread started as a suggestions/best practice but I like where this is going. Realistically I've got a set of HX mains coming from gmduramax. I am likely just going to plastigauge everything as I don't think the mains will need to be touched up. I'm going with LBZ or LML rods so I should be fine to use stock bearings.

 

[M.A.M.]

You guys can quit hiding that it was SoCal Diesel that said it. I’ll even post the thread lol.

https://www.duramaxdiesels.com/forum/showthread.php?t=78533

Regardless of the taper, my concern was there was still .0005 thicker at the ends of the taper on a H vs a HX. Not the case. I was wrong there

that’s my thread, but a local shop did my machine work, not SoCal. As much as I would like to have an engine from SoCal! Maybe someday...


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[Chevy1925]

that’s my thread, but a local shop did my machine work, not SoCal. As much as I would like to have an engine from SoCal! Maybe someday...


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Ah I got ya. That does back it up though!

 

[TheBac]

This thread started as a suggestions/best practice but I like where this is going. Realistically I've got a set of HX mains coming from gmduramax. I am likely just going to plastigauge everything as I don't think the mains will need to be touched up. I'm going with LBZ or LML rods so I should be fine to use stock bearings.

Welcome to what this forum was like regularly up til about 2012. Lots of ideas shared while trying to solve a problem. Good to know that spirit is still here.

 

[Bdsankey]

Welcome to what this forum was like regularly up til about 2012. Lots of ideas shared while trying to solve a problem. Good to know that spirit is still here.

This is why I joined this forum. It's nice seeing guys who are like "yeah I've got these parts I don't need and can help you out to get them off my shelf". It's also nice getting information that I don't know. I'll be the first guy to say I know minimal about actual engine setup. I paid my machine shop to measure and supply me bearings because I trust their measurements and reputation. I can assembly it no problem, but the actual setup/measurement/determining bearings needed I have no clue.

 

[rcr1978]

So if this is acceptable, RCR1978 shoot me a text on those bearings. 906-284-0962.


This thread started as a suggestions/best practice but I like where this is going. Realistically I've got a set of HX mains coming from gmduramax. I am likely just going to plastigauge everything as I don't think the mains will need to be touched up. I'm going with LBZ or LML rods so I should be fine to use stock bearings.

I had the oil pump not the bearings

 

[Bdsankey]

I had the oil pump not the bearings

My bad!

I’ve still got a full set of rod bearings. It’s split half H/half HX. Installed a split set into mine when it was apart last time.


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Let’s try this again lol. What are you looking to get for the bearings?

 

[M.A.M.]

Let’s try this again lol. What are you looking to get for the bearings?

$160 shipped



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[Bdsankey]

$160 shipped



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I’ll take em. Can you shoot me a text? 906-284-0962

 

[Bdsankey]

So, oil pump relief shimming and oil pumps. Gabe at SoCal was telling me they turn away quite a few Melling pumps for quality issues before they go onto the shelf. That said, how big of a shim are people putting in the pump relief? I'll be running LML oil cooling nozzles, 2020 cooler, and compounds so I have some oil hungry items.


My plan is to feed both chargers off of the oil galley instead of the valley charger feeding off the cam. I feel much more comfortable with that idea as it should help the cam bearings live longer/hold higher pressures.