Lb7 built bottom end assembly questions.

[lmmcbrown0917]

I have assembled plenty of gas engines in the past but i know this is a whole different ball game. I have plenty of experience with duramaxs and work on them everyday but I've never torn apart a bottom end, I guess I'm just looking for some advice on some things. what do i need to know as far as specifics, checking clearances and such?

Parts list for the bottom end: Lb7

Fully Balanced
Carrillos
Std Bore Mahle cast 16.5:1 with 75 pockets
keyed stock lb7 crank
Clevite bearings
Ati dampner
Empire af cam
Arp heads and main studs


Any advice greatly appreciated,

Thanks.

 

[DewDewMax]

check, check and re-check again! everything is pretty well the same as a gas motor (mechanically wise) Proper crank end play, check crank runout, cam run-out, main clearance, rod clearance etc! any questions and i am sure there is lots of people who will chime in!

 

[TheBac]

Yep, everything is pretty much the same as a gas engine, except the parts are larger and there are more steps. :roflmao: Checking protrusion and clearances are critical, just like on a gasser.

 

[motoking_1990]

It's too bad I forgot most of that stuff. I'm gonna have to break out the book when I do mine. I don't do that stuff everyday.

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[lmmcbrown0917]

What "tools" do you guys recommend using to check clearences? And as far as numbers go what should clearances be? I plan on using clevite "hx" rod, main, and thrust bearings.

The air/fuel setup on this truck will be capable of 1000hp eventually so I would like it to be right, also anyone know of a good machine shop around Charlotte NC that can possibly align hone and torq plate hone a duramax block?

Thanks.

 

[DewDewMax]

Yep, everything is pretty much the same as a gas engine, except the parts are larger and there are more steps. :roflmao: Checking protrusion and clearances are critical, just like on a gasser.

you forgot 25 times as expensive:roflmao:


and inside mic, outside mic, plastigauge, bore gauge etc!

 

[TheBac]

you forgot 25 times as expensive:roflmao:


and inside mic, outside mic, plastigauge, bore gauge etc!

True that, plus some.....

 

[DewDewMax]

What "tools" do you guys recommend using to check clearences? And as far as numbers go what should clearances be? I plan on using clevite "hx" rod, main, and thrust bearings.

The air/fuel setup on this truck will be capable of 1000hp eventually so I would like it to be right, also anyone know of a good machine shop around Charlotte NC that can possibly align hone and torq plate hone a duramax block?

Thanks.

If you ask one builder to another theyll all give you different numbers on clearances, all comes down to preference, I built mine looser on the mains h series were to tight ran hx's which I ended right around .00285 across the board and h on the rods gave me right around .0030 across the board! everyones opinion is different!

 

[lmmcbrown0917]

I noticed there was a list of clearances in the haynes manual i had laying around. do people usually run different clearances for high hp builds versus stock builds?

 

[IOWA LLY]

Yes they sometimes do. But that doesn't mean it's right.......

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[motoking_1990]

So which is better tighter or loose clearances and for what kind of application? Tighter seems like there would be more heat directed at the bearings.

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[DIESELMAFIAPER.LB7]

I run pretty close to factory or right in the middle of specs iirc on everything other then the rings which mahle suggested a different clearance for. 5k miles 800 rwhp no issues so far.

If you know how to rebuild a gas engine you can do a duramax just fine imo there just as simple

 

[S Phinney]

I usually run rods in the .0025-.003 ranges and mainstream from .003 to .004. If you use HX mains and line hone to max spec you should come in around .004. A little extra over stock would be best for a high hp build. Looser mains seem to have less crankshaft failures from most builders that I have talked with.

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[motoking_1990]

Good information thanks!

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[lmmcbrown0917]

I usually run rods in the .0025-.003 ranges and mainstream from .003 to .004. If you use HX mains and line hone to max spec you should come in around .004. A little extra over stock would be best for a high hp build. Looser mains seem to have less crankshaft failures from most builders that I have talked with.

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Thanks for the good info! what bearings would usually get me in that clearance range for the rods? I was also wondering about the thrust washers for the end of the crank and the clearances there?

thanks.

 

[S Phinney]

Thanks for the good info! what bearings would usually get me in that clearance range for the rods? I was also wondering about the thrust washers for the end of the crank and the clearances there?

thanks.

Use the H bearings on the rods.

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[lmmcbrown0917]

Use the H bearings on the rods.

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Any info about the the crank clearances and thrust washers?

 

[S Phinney]

Any info about the the crank clearances and thrust washers?

Crank end play spec is .0016 to .008 with a limit of .0213. Cam end play limit is .0079. Rods .0014 to .003 with a limit of .0039. Crank .0015 to .0028 with a limit of. 0055. Line bore is 3.3464 to 3.3472. If you go to the 3.3472 you can use either have or HX bearings and be fine. HX will put you more in the .004 range on clearances. I prefer the rods in the .002 to .0025 range and mains .003 to .004. It is fine to run mains a little tighter without issue but that's just my preference.

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[lmmcbrown0917]

Crank end play spec is .0016 to .008 with a limit of .0213. Cam end play limit is .0079. Rods .0014 to .003 with a limit of .0039. Crank .0015 to .0028 with a limit of. 0055. Line bore is 3.3464 to 3.3472. If you go to the 3.3472 you can use either have or HX bearings and be fine. HX will put you more in the .004 range on clearances. I prefer the rods in the .002 to .0025 range and mains .003 to .004. It is fine to run mains a little tighter without issue but that's just my preference.

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Thanks for all the good info!