Installed new main and rod bearings (worried) - Team Camaro Tech
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post #1 of 10 (permalink) Old Mar 12th, 03, 01:18 PM Thread Starter
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I just rolled in a new set of rod and main bearings for my 400sbc last weekend with the help from a guy that works at Knechts. Getting out the front top main bearing was the hardest, we started to roll it out by pushing on one side and then pulled it around with this dental like pick instrument. During pulling it out, he slipped with the pick and it hit the crank journal, making small mark. He didn't say anything when it happened he proceeded to get it out, but it has me worried, (This is the first time for me doing any bottom end work) I just put the pan on and sealed it too, but the engine is still on a stand. Any advice, should I be worried? He said that the journal surfaces looked good when we took the other bearings out.

By the way, this is a engine I bought from a guy earlier this year that has less than 3000 miles on it, I wanted to check bearings to see if he was telling truth, bearings had little wear, just scratches due to what we think was from particles or lint/dust.

Sorry long, just worried.
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post #2 of 10 (permalink) Old Mar 12th, 03, 01:36 PM
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The only proper way to replace them is to disassemble the engine, have all the parts checked by a machine shop, and then re-assemble checking all clearances. A scratch on the crank will eat into the bearing immediately as soon as the engine spins over. Will it blow up? Probably not but if you're going to all the trouble of removing the engine to put the bearings in, it's a real good idea to check out all the parts. If the bearings needed replacement then the rings probably do too. It may seem like a hassle now but imagine the fun of pulling it back out and apart later.

Just my two cents but he should have said something when he slipped. Heck, he shouldn't have even done the bearing replacement without a complete disassembly. You have no idea what the bearing clearance is, etc. Cleanliness and proper clearances are everything to having an engine that runs well and lives a nice long life.

Jody


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post #3 of 10 (permalink) Old Mar 12th, 03, 01:56 PM Thread Starter
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We did plastigage the main and rods and they were right in there. I just don't know if I should pull the whole thing apart again.
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post #4 of 10 (permalink) Old Mar 12th, 03, 03:16 PM
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Well, the fact that your even asking the question her on the board tells me you won't rest assured until you fix it right. I agree with Cam, to do it right you should have everything checked and clearanced. But, you can cut corners and have sucess too. Check out this set up,
http://members.aol.com/capsgs/badstart.htm
400.00 rebuild and it runs 11.31.
Never say never,

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post #5 of 10 (permalink) Old Mar 12th, 03, 03:57 PM Thread Starter
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Well I am going to talk to the guy that helped me do the bearings tonight and see what he thinks of it. Like I said, we checked the rod and main bearing clearences and the crank journals were all nice and shiny. We cleaned around the mains by taking a lint free cloth and ran it around the journal with the top main bearing out and rubbed them clean. Just the front top main bearing worries me.
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post #6 of 10 (permalink) Old Mar 12th, 03, 05:27 PM
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As for the nick in the crank, the best you can do is take a ceramic stone and work down any high spots you find. Don't file it. Don't use emery cloth until you've got the worst of it removed with the stone. Emery cloth would be fine for a followup, but I'd oil it up first and use at least 800 grit or finer. Work evenly around injury and feather it out around the journal. You'll need to make sure you remove any particles of metal and grit before reassembly.

If we're talking a factory motor, you probably don't have to be quite as concerned with bearing clearance. They tend to be a bit looser than most perfromance engine builders specs. Plasti-guage is probably close enough. Although I don't disagree with others concerns.

-dnult

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post #7 of 10 (permalink) Old Mar 12th, 03, 06:26 PM
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If your taking it apart again your only looking at the price of a few gaskets to get the crank out and do the job right in the first place. All the trouble you just went to getting the top bearings out is alot more work than just pulling the crank out and doing as it should have been done the first time. The name you mention this guy works at, I don't know it so I am assuming he builds engines? He of all people should know the right way and the cheesy way of fixing/checking something out.

This is what I would do if I were you. Get some rod boots, mark if they are not already marked the rod caps and pull the entire crank out. Don't forget to mark the main caps also. If you have a nick in the #1 main journal you are going to spin a main bearing. if this happens the engine will most likely be junk. I would take the time to fix it right while you can and not cheese it together. Your questions and concern are valid. Follow your gut on this one. You can have the crank polished for about $30.00, gaskets and new rear seal will be about $25.00 and new bearings (rod and main)about $50.00. For the money it's cheaper to do it this way......it could cost you thousands down the road,50 miles or 5000 miles who knows.

Just my opinion.......Some of the wording sounds kinda harsh after reading this, please don't take it as an a$$ chewing.

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post #8 of 10 (permalink) Old Mar 12th, 03, 07:56 PM Thread Starter
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Thanks for the great replies. I know I can count on you guys to be completely objective in your opinions. I have a few questions regarding the crank and bearings now since I will probably have it polished. Since I put in new Clevites for the crank, rod are .020 and crank is .010, would I still need to get another set? I turned the engine by hand a few times after installing all the bearings so I don't think they would be hurt. I will look at them but if no real scratches I should still be able to use them right?

My other question concerns the crank after it is polished. Would the clearences be a bit looser now? How much material does polishing usually take if I took it to a machine shop?

Once again thanks guys....I really sealed that oil pan good too. Shoot
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post #9 of 10 (permalink) Old Mar 12th, 03, 09:51 PM Thread Starter
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Also do you think dnult's suggestion would work too if the scratch is minimal and I use the method he described in getting it out?
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post #10 of 10 (permalink) Old Mar 13th, 03, 05:51 AM
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I know the stone solution will work from first hand experiance, but if you have never done it I would say don't do it. Your bearings should be ok, but take a good look at the one where the sratch is and have the shop polishing the crank look at them also.
As for clearances, assemble the main caps with tne bearing shells in them and get a snap-gauge and micrometer and measure the bearing after torqueing each cap to spec. Then measure your crank. Subtract the reading you get from the crank from the reading you get with the bearing and you have your clearance. If you fall within specs, which I am sure you will you should be fine. If not ask you crank grinder about special sized bearings that fix these problems, they are not much more than standard sizes. A little loose will not hurt a thing though. Make sure when you put her back together to set you thrust on the rear main. You do this by placing the cap on the block with the crank in, tighten down on the cap then lossen the bolts to allow it to move then thrust the crank fore and aft to alighn the trust portion of the upper and lower bearing shells with each other and the cap with the block. Using a large screwdriver keep the crank trusted in one direction and tighten down the rear main cap, but do not torque to spec.

Torque the Crank in 3 stages starting with the middle main cap and work out and bring it to full torque in 3 stages. Take you time so you don't nick a rod journal and make sure you get that timing chain on right, also remember that on a timing set DOT to DOT (CAM DOT @ 6:00 and crank [email protected] 12:00)is firing #6, crank DOT at 12:00 and Cam Dot at 12:00 is firing #1. This just makes it simpler when putting the engine back in the car.....you know where your at already. [img]graemlins/clonk.gif[/img]

Joe
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Then, you have enough horsepower."
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