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Old 02-23-2009, 09:02 PM
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steps to installing main bearings?

this is my first build and i just got the block and crank back from the shop after having the block honed w/torque plate, clearances checked, crank polished as well as the rotating *** balanced. amoungst other things. said standard size bearings would be fine (newer vortec block). just wanted to make sure i do this right. any suggestions more than welcome.

yes or no:
1. light assm lube on crank journal and bottom bearing
2. set crank in, light assm lube on top
3. set in plasigauge light lube on top bearing and cap
4. torque cap down
5. take back apart and check plasigauge for .002-.0022 clearence.
6. if checks out. assemble?

is this pretty much the same for the rod bearings as well?

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Old 02-23-2009, 10:12 PM
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Assemble your bearing shells in their "home." First make sure you wipe down the saddles AND bearings with a solvent on a lint-free rag. That is very important. I like to wipe them down with acetone on a shop towel, then blast them quickly with brake parts cleaner. The brake parts cleaner evaporates completely leaving nothing behind, and it also rinses off any possibility of lint. I also like to use a plastic mallet to tap the bearings into place from the ends. Avoid smooshing them in by just pushing down on the center with your thumb. They could deform.

Lay the crank in dry to check with plastigage. The whole point is to measure the clearance without anything in the way.

Then when you have satisfied yourself on clearances, re-clean. Assemble the bearings in their saddles dry to make sure they seat, but then liberally coat the bearing surfaces and journals with engine oil for assembly. Assembly lube should only be used on direct frictive surfaces like flat cam lobes, rocker arm ends, and lifter bases. Here's why: the journals of the crank are lubed by oil under pressure. The journals are suspended between a pressurized layer of oil. That is why you are checking it with plastigage; too much clearance and the oil can squish out too fast. Not enough clearance and the oil won't be able to get in there fast enough. If you go slathering thick assembly lube in there, you will be preventing the even distribution of oil during the critical startup. The other big reason not to use assembly lube on crank journals is because most assembly lube contains lubricant particles that are caught in the filter. Excessive use of assembly lube can pretty quickly clog the filter which causes it to bypass. The WORST time for a filter to bypass is during initial start up when there are potentially tons of metal shavings in the engine.

On a flat-cam engine, I use assembly lube on the cam lobes, lifter bases, pushrod ends, and rocker arm tips. On a roller cam engine, I skip the lifters and lobes. Use it where you need it, but nowhere else. The journals do not need assembly lube... especially because you're going to prime the oil pump before you start it anyway, which will fill the journal gaps with fresh oil and flush out half of the assembly lube anyway.

So, to answer your questions:

1. light assm lube on crank journal and bottom bearing: No. Dry until you plastigage
2. set crank in, light assm lube on top: No, keep it dry
3. set in plasigauge light lube on top bearing and cap: Dry.
4. torque cap down: Yup. Make sure you don't draw the cap down by torquing it. Seat it with a deadblow mallet. I've seen too many that were drawn down against the cap shoulder and cracked.
5. take back apart and check plasigauge for .002-.0022 clearence: Yup
6. if checks out. assemble?: Yup... assemble the bearings in their saddles dry and lint-free. Then put the crank in place with engine oil on the bearings and journals. Torque it home.

Last edited by curtis73; 02-23-2009 at 10:18 PM.
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Old 02-23-2009, 10:33 PM
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thank you so much, i've been looking all over for just this. is .002-.0022 correct? also do you have a recomendation for type/weight of oil to use?
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Old 02-23-2009, 10:39 PM
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I'm fixing to do a first build also, What would be the next step...? check crankshaft endplay...? I also heard it was a good idea to torque the the thrust cap with the oil pump in place....?
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Old 02-23-2009, 10:52 PM
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Before you set your crank don't forget to give it a good cleaning. Use a rifle cleaning type bush and solvent to get all the oil passages then use your air gun to blow it out. I assume your block is spotless, right?
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Old 02-24-2009, 05:11 AM
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of course, still sealed in the bag the shop puts them in. i have a factory roller so is there a need for me to check endplay?
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Old 02-24-2009, 08:58 AM
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The chances that endplay would be off are slim... but its so easy to check that it can't hurt.
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Old 02-24-2009, 08:59 AM
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Quote:
Originally Posted by slate84
of course, still sealed in the bag the shop puts them in. i have a factory roller so is there a need for me to check endplay?
the shop may have missed some grit , so brake clean and then air blow out each hole in crank .
use a light dab of silicone at the edge of main cap from seal to where oil pan seal goes .
when your satisfied , your a pro .
oil only on them bearings as stated earlier .
i put lucas mix with oil on everything
the main caps and rod bolts should be oiled , and where the nut goes against cap on rods .
the underside of the main bolts and the treads .
this to insure accurate torque of them .
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Old 02-24-2009, 09:18 AM
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Quote:
Originally Posted by slate84
thank you so much, i've been looking all over for just this. is .002-.0022 correct? also do you have a recomendation for type/weight of oil to use?
A generic answer for a street engine is between .001 and .002, but I've seen guys be happy with as much as .003. You can accept tighter tolerances on the #1 main as little as .0008" but it depends on your application.

Use 10w30. That should be spot on. Shoot for 15-20 psi at hot idle, and never more than 70-80 psi.
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Old 02-24-2009, 11:12 AM
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Quote:
Originally Posted by slate84
this is my first build and i just got the block and crank back from the shop after having the block honed w/torque plate, clearances checked, crank polished as well as the rotating *** balanced. amoungst other things. said standard size bearings would be fine (newer vortec block). just wanted to make sure i do this right. any suggestions more than welcome.

yes or no:
1. light assm lube on crank journal and bottom bearing
2. set crank in, light assm lube on top
3. set in plasigauge light lube on top bearing and cap
4. torque cap down
5. take back apart and check plasigauge for .002-.0022 clearence.
6. if checks out. assemble?

is this pretty much the same for the rod bearings as well?
No lube with Plastigage, not that it does anything, but it add to the mess you have to clean up.

- Install the main bearings into the block, check for oil hole alignment. The way I do this is apply Prussian Blue around the oil hole in the saddle, install the bearing shell, remove the shell look at the imprint on the saddle's oil hole versus that in the shell. If there is a mismatch using a high speed grinder reshape the shell to match the saddle's oil hole location. With a fine Jeweler's file remove any burrs. This insures that the oil is being delivered to the bearing in a full amount and the backside of the shell isn't being pressurized.

- Mark the location of each shell for the saddle it resides in, I use an electric engraver on the back of the shell with a light sanding with fine 400/600 wet dry paper to make sure there's no raised burrs.

- Clean everything in the saddles and shells with a high energy solvent like lacquer thinner or brake cleaner and a lint free rag.

- Install the upper shells into the saddles they're marked for.

- Set the crank in place and apply a strip of Plastigage on the journals. Install the bearing shells with the caps. Lubricate the bolt threads with the appropriate lube and torque them up. I've assumed that you've cleaned the threads in the block with the proper tool which isn't a tap. Use something like this http://www.stefs.com/bandb/products/...ningtapset.htm

- Remove the main caps and measure the clearance by journal with the Plasigage gauge.

- If everything is in order, continue to the next step, which is properly installing the thrust bearing. You'd be surprised how many guys miss this, most probably get buy but a few don't and those that don't find it an expensive error.

- First, set the thrust bearing into place and torque up the cap, inspect the mating point between the upper and lower halves. This must be smooth with no offset, an offset will wipe the lube out and ruin the bearing and the crank. Undo the thrust main and install the mains into their saddles.

- Reinstall the mains but this time with assembly lube as we are going to be rotating and skating the crank about. Drop in the crank and loosely install the main caps. You will need a big pry suitable for moving the crank fore and aft in its bearings. Bring all the cap bolts up to 5-10 foot pounds moving the crank against its fore and aft limits with the pry. Continue this till the mains are torqued up.

- With a bright light inspect the fit between the upper and lower thrust halves. Assuming this is still good, measure the gap for proper thrust clearance.

If all of this is within spec, you can continue to rod installation. The rod bearings are installed the same way as the crank mains but since the crank has to be rotated for access to the rod fasteners, the pistons and rods are assembled in pairs by journal.

- Assemble dry with Plastigage, torque the fasteners, check the side clearance, disassemble and check the Plastigage clearance.

- Clean, then lube and reassemble, then continue on to the next pair and repeat the process.

Bogie
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Old 02-24-2009, 11:27 AM
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PLEASE DON'T MISS THIS IMPORTANT STEP.....

Make certain you have the correct size bearings... given the steps here, I did not check the bearings and "assumed" they were at least close to correct. "NOT" they were way out by like .030 and when I went to plastigauge and torque... I broke my bearing blocks!

either wet fit or mic to make certain they are at least the correct bearings prior to any torqueing!

see my post here :

Not a funny story (Long) AutoZone & Hi-tech components
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Old 02-24-2009, 12:19 PM
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ya, just read that, that sucks. i'd say both faults but you can't help feel like they got the ball rolling on it. pm me if you'd like with what you got from them, really curious?
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