LB7: Daily Driver/Tow Rig Rebuild

[Bdsankey]

I am wondering if some of you with more experience can shed some light on bearing choices. Right now my LB7 is getting tired and dropping oil pressure. I've been looking at the Mahle 789-1011 rebuild kit which has pistons, rings, wrist pins, cam bearings, main bearings, rod bearings, thrust washers, upper gasket set (either LB7 or LLY, dictate VIN when ordering), head gaskets in your choice of grade, and lower gasket set. Bearing and piston sizes are specified when ordering.


What my question is, is it worth while to get the H series bearing (piece this together vs buying the Mahle kit) or will the P series be just fine for a DD/tow rig that will not have intent of going above 550-600hp? I'm planning on doing a 475 over the stock IHI to help EGT towing, I do not intend on pushing it to make peak power as I have a full built LLY for that. Is it also worthwhile to go to LBZ/LMM or LML rods while it's apart for peace of mind?

I'm also planning on adding the following:
1) Melling M316 pump
2) LML piston cooling nozzles
3) 2020 oil cooler
4) Main studs
5) Flexplate bolts
6) Billet flexplate
7) New GM damper
8) SoCal 3388 cam (possibly)
9) New GM LLY lifters (if I change cam)


Block will get:
1) Checked for cracks
2) Decked
3) Bored/honed for new pistons
4) Mains honed
5) Press in plugs converted to threaded in the oil galley
Note-I'll also polish the crank and re-balance the assy.

 

[Chevy1925]

delip the pistons and dont run those 41909 rings. search my started threads and you see why.

put LML rods in if you are balancing the rotating assembly.

i prefer H bearings but P's would probably be just fine. plenty of guys running that HP on stock bearings still. usually the cam bearings go first from lack of oil/pressure.

NPT oil galley plugs must be threaded in FLUSH to the block once installed or you will have a headache there.

if EGTs are running hot on a 30hp tune, something aint right. if you run a 75hp tune with twins, your gunna need a built trans.

 

[Bdsankey]

delip the pistons and dont run those 41909 rings. search my started threads and you see why.

put LML rods in if you are balancing the rotating assembly.

i prefer H bearings but P's would probably be just fine. plenty of guys running that HP on stock bearings still. usually the cam bearings go first from lack of oil/pressure.

NPT oil galley plugs must be threaded in FLUSH to the block once installed or you will have a headache there.

if EGTs are running hot on a 30hp tune, something aint right. if you run a 75hp tune with twins, your gunna need a built trans.

Would it be worthwhile putting in the Mahle motorsports pistons IF my factory pistons are out of spec or should I just slam in some GM pistons? If my factory pistons are usable (not too much PTW clearance) then I'll put new rings on them and still run LML rods as I think they are relatively cheap. If I have to replace pistons then LML rods are going in no doubt. Do they use the same bearing? If the pistons are usable . Gmduramax might have a set of H bearings on the cheap as I have not seen an engine require anything but standard bearings as long as it didn't spin a bearing or run without oil pressure.

As for the plugs, yes, they will be flush. My last motor build in my LLY I had this done and made it very clear that the plugs must be flush or slightly recessed. I haven't had any issues on my LLY thus far.

EGT is hot on the 75hp towing tune running in Nebraska up their large hills at 80mph grossing 24k lbs. EGT isn't an issue on a 30hp tune. I am planning on building the trans come spring but I believe the oil pressure issue is more concerning at the moment. The trans is holding up fine on everything but the big tune (another reason it lives in the 30hp tune) which is a 230hp built trans file (long story). The 120hp street tune is fine. It'll be getting a Goerend R and full build kit with G4 clutches when they come out. If it fails sooner I'll put GPZ in C1/C2 and G3 in C3/C4.

 

[Chevy1925]

you're not going to be able to run those pistons without a decent amount of P to W clearance. by the time the block is honed, its going to be large. unless you dont care about burning some oil and little piston rattle on cold starts. many guys have done this in the past but it was back when budget builds were the thing and they were generally strictly a performance build.

that said, mine went 60k with a .0045 initial p to w clearance. i never did measure it out to where it is now. might do that for fun tonight and see what the old block/pistons come to now after a total of 220k on the pistons. it just burned a quart/quart and a half every 2k.

bearings are all the same 01-16. you cant get oversized bearings so if someone spins a bearing or hurts a crank, its trash.

 

[gmduramax]

I have HX main bearings and the standard rod bearings.

 

[Bdsankey]

I have HX main bearings and the standard rod bearings.

Can I run HX on 15w40? And standard as in size or standard as in P series?

 

[gmduramax]

Can I run HX on 15w40? And standard as in size or standard as in P series?

Yes and P series

 

[Bdsankey]

Yes and P series

How much you looking to get for the mains?

 

[M.A.M.]

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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[Bdsankey]

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.


Sent from my iPhone using Tapatalk

What was the reasoning behind a split set, just what clearances required?

 

[TheBac]

Im still on the 41909 rings (60,000 miles), but James is right....we found out later that they arent the proper ones. Go with what he says.

 

[M.A.M.]

What was the reasoning behind a split set, just what clearances required?

Yeah, I had my crank magged and polished, and wasn’t happy with the clearances with either set, so I split them.


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[Bdsankey]

Im still on the 41909 rings (60,000 miles), but James is right....we found out later that they arent the proper ones. Go with what he says.

Seems like the consensus is Mahle performance cast. They come one of 2 ways, 16.8:1 without reliefs or 16.5:1 with 0.075” reliefs. I don’t think I’ll need reliefs as the biggest cam I’ll put in is a 3388 which will work just fine for a 475 over stock compound setup AND allow me to turn the torque up with LML rods. Are the included rings with the performance pistons decent or should I go with something else?

I’m pretty set on the M316 oil pump, LML piston cooling jets, and 2020 cooler. I feel those parts will help ensure a healthy oiling system on a tow rig. I just don’t know what clearances I can run on 15w40, I usually have the machine shop measure and supply bearings but they charge a decent markup vs what I can get them for.

 

[gmduramax]

How much you looking to get for the mains?

$75 shipped

 

[Bdsankey]

$75 shipped

I’ll take em. Shoot me a text. 906-284-0962

 

[rcr1978]

I have a new melling pump I would sell if your interested, I bought it for my motor took it apart to make sure it was clean and wanted to see if it actually was bigger than the OEM one and it's identical only difference is the iron housing, and pressure relief valve so I didn't use it.

 

[Bdsankey]

I have a new melling pump I would sell if your interested, I bought it for my motor took it apart to make sure it was clean and wanted to see if it actually was bigger than the OEM one and it's identical only difference is the iron housing, and pressure relief valve so I didn't use it.

From what I can tell the M316 is higher output as the gears are a different thickness (if my searching didn't come up with incorrect information). What are you looking to get for it?


I have been told you can run an LML pump if you machine down the cover, I don't know if that is accurate the. I've never done it but I also don't know if it is a benefit over the Melling M316 pump.

 

[rcr1978]

The melling is the same size as the stock, gears measure same diameter, thickness and gear count basically identical other than shitty machine work and higher pressure relief valve. Probably do $200 shipped on the pump

I went to a LML pump and oil nozzles
Read this
https://www.duramaxdiesels.com/forum/showthread.php?t=42505&page=2

 

[Bdsankey]

The melling is the same size as the stock, gears measure same diameter, thickness and gear count basically identical other than shitty machine work and higher pressure relief valve. Probably do $200 shipped on the pump

I went to a LML pump and oil nozzles
Read this
https://www.duramaxdiesels.com/forum/showthread.php?t=42505&page=2

I read this about 10 minutes ago hahaha. Seems like I can machine a LML pump to fit as well as notching the upper pan/windage tray. I'd swap to the LML pickup tube. Other than that it seems pretty straight forward but nobody can seem to to tell me which actually moves more oil. Everyone says the Melling moves ~10%+ more oil and the LML is ~11% more. Cheaper/easier option is Melling.


I will also be going to LML cooling nozzles to keep the pistons cooler for towing since that is mostly what this engine will see.

 

[rcr1978]

Not sure how correct these are but these were my calculations when I did mine

Oil pump gear teeth 33
Crank gear 59
= 1.787 ratio overdrive
GPM
650rpm=1161 4.35/4.86
2000 =3574 13.39/14.96
3200= 5718 21.42/23.94
3600= 6433 24.09/26.94
4000= 7148 26.77/ 29.93
OLD/LML
.
The copy/paste didn't work so well, data goes from Engine rpm to pump rpm, the old pump gpm vs LML gpm. This was just using a pump calculator per gear/housing specs ect.