LB7: The Rebuild, Ch.2 -- Building slowly

TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Figured Id weigh the pistons and rods in advance of having the rotating assembly balanced, so I got out the trusty digital mailing scale and this is what I found:

Pistons (with pins, w/o rings):
1) 1273 grams
2) 1274
3) 1274
4) 1274
5) 1273
6) 1274
7) 1273
8) 1274

Called Merchant to thank him for getting the pistons so darn close, but he said it was a fluke.

But.....

LBZ rods (w/caps & bolts, w/o bearings)
1) 1176 grams
2) 1176
3) 1180
4) 1169
5) 1186
6) 1175
7) 1193
8) 1173

I weighed every rod and piston twice to make sure. But is it normal for rods to have a 20 gram swing like that? Should I be concerned? Where should the shop pull weight to balance them out?

Found this thread concerning rod/piston weight: http://www.duramaxdiesels.com/forum/showthread.php?t=627&highlight=rod+weight
Looks like my findings follow along with Pat and Ben's.
 
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MrUPS

MrUPS

New member
Mar 18, 2009
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Northwest Pa
I've just spent the last 40 min. reading this thread. Its good reading after a long day of work! Maybe you should talk to UPS about a sponsor. :rofl::rofl: If you management is like mine the only thing you'll get is more stops! Great thread I hope the build works out well for you.
 
TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,677
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Mid Michigan
Mafia, did your shop clean up the casting roughage on the beams too? Where did they remove weight -- on the small or big ends?
 
dmaxvaz

dmaxvaz

wannabe puller
Nov 22, 2006
1,132
0
0
46
METRO DETROIT
thebac said:
figured id weigh the pistons and rods in advance of having the rotating assembly balanced, so i got out the trusty digital mailing scale and this is what i found:

pistons (with pins, w/o rings):
1) 1273 grams
2) 1274
3) 1274
4) 1274
5) 1273
6) 1274
7) 1273
8) 1274

called merchant to thank him for getting the pistons so darn close, but he said it was a fluke.

But.....

lbz rods (w/caps & bolts, w/o bearings)
1) 1176 grams
2) 1176
3) 1180
4) 1169
5) 1186
6) 1175
7) 1193
8) 1173

i weighed every rod and piston twice to make sure. But is it normal for rods to have a 20 gram swing like that? Should i be concerned? Where should the shop pull weight to balance them out?

Found this thread concerning rod/piston weight: http://www.duramaxdiesels.com/forum/showthread.php?t=627&highlight=rod+weight
looks like my findings follow along with pat and ben's.
Click to expand...

tom, i have a set of lbz rods that have been balanced to each other if you want to use them, a balanced crank to match too...
 
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TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,677
1,947
113
Mid Michigan
Got my 30% injectors back Monday. PDI told me all the injectors flow tested and balanced out excellent before he rebuilt them, and they are as good as new. Also received my manifolds and uppipes from Rick. :thumb: Man, are they nice. I highly recommend them.

Shortblock is done. :D Rod bearings all checked out at .001-.002 clearance, with most being between .001-.0015. Those Mahle (Perfect Circle) rings were right on...didnt have to file a single one.

Had a few concerns, but theres nothing I can do about them now. I would recommend linehoning if there was evidence of cap walking, though (something I didnt do but probably should have). Thanks Rob and Eric for taking my calls and lessening my fears.

Will try to get protrusion figures tomorrow. Hope to have heads on tomorrow night.
 
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TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
Crank endplay ended up being .004. On the money.

Protrusion results:
1 - .012
2 - .014
3 - .013
4 - .013
5 - .014
6 - .015
7 - .014
8 - .015

Looks like the C gaskets were the correct choice. Should be able to get most everything else installed tomorrow except for the front and rear main seals.

Question: I installed the injector cups last week, but am not satisfied with the job I did and would like to remove them and redo the job. How do I pop the cups out??

The red loctite I used just ran down the sides of the cups instead of staying put, and Im not sure just how sealed they are. I bought some of the red gel to redo them.
 
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TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,677
1,947
113
Mid Michigan
Naw, Tim....a "serious runner" would have had studs and rods. All I just hope for now is it stays together.

Just reporting what Im doing so that others can see whats up when you rebuild one of these. Its not all that tough if you've ever rebuilt an engine before, just a lot more steps. Im on step 97 of 138 on Alldata right now. That site has had every scrap of needed info except for how to clock the piston rings so far. Helps that I have the people here to bounce questions off of, too.
 
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TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,677
1,947
113
Mid Michigan
Whoops....forgot to move this info into this thread. It would be before post 168:

Concerning balancing the crank:

Crank has two new heavy-metal (tungsten?) plugs, one on the first counterweight, one on the last. The machinist said, and I quote, "We had to use every piece of bobweight we owned, and then we were worried that the rods were long enough to handle those weights." "Thats one heavy SOB." Flywheel and balancer were not touched.

Rods were a pain from what I was told. Heaviest rod had a sizable amount of metal removed from the big end just to get it within range of the other seven (it was ~24g heavier for some reason). Seven rods had metal removed from the small ends, and six had metal removed from the large ends. In the end, all the rods came out to 1168g. Very nice.

Pistons werent touched. Didnt have to be. They were all within one gram of 1272. Again, very nice.

If you run different rods, dont mess around, get the crank balanced.
Click to expand...
 
stroke250

stroke250

I May Be Lost...
Jul 1, 2008
490
18
18
Idaho
TheBac said:
Crank endplay ended up being .004. On the money.

Protrusion results:
1 - .012
2 - .014
3 - .013
4 - .013
5 - .014
6 - .015
7 - .014
8 - .015

Looks like the C gaskets were the correct choice. Should be able to get most everything else installed tomorrow except for the front and rear main seals.

Question: I installed the injector cups last week, but am not satisfied with the job I did and would like to remove them and redo the job. How do I pop the cups out??

The red loctite I used just ran down the sides of the cups instead of staying put, and Im not sure just how sealed they are. I bought some of the red gel to redo them.
Click to expand...



tom, did you use the red loctite 271?? if you are worried, pull them and use the 272. its more of a gel in a bottle and has a higher temp rating.
 
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TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,677
1,947
113
Mid Michigan
Looking more like an engine every day. Just assembling one of these engines takes quite a long time.
As stated earlier, I popped one of the cups, and found the loctite had sealed it well, so I left well enough alone.

Working on installing the fuel system now. Should have everything done by Monday, barring more "honeydos". :rolleyes:
 

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TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,677
1,947
113
Mid Michigan
I decided to leave the engine looking exactly the same way I pulled it, minus most of the dirt and grease. :rofl:
 
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