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-   -   Should a newly installed crank be tight? (https://forums.off-road.com/gm-standard-ifs-trucks-suvs/32195-should-newly-installed-crank-tight.html)

**DONOTDELETE** 07-24-2000 08:28 PM

Should a newly installed crank be tight?
 
Started putting my 350 together this evening. I checked the clrance between my stock .010 under crank and the matching Clevite77 main bearings with plasti-gauge. The clearances were well within spec (from Haynes book). I lubed up the half of the bearings in the block, placed in the crank, lubed the top half of the main journel (the half still sticking up), smeared a little silicone around the surface of the rear cap, and installed the main caps. I tightned all the bolts to 30ft.#, then went back and tightned the long bolts to 75 and the short bolts to 65 ft.#. Im using the book "Rebuilding Small Block Chevys" by David? Visard as a guide. The book said that the crank should turn freely when the caps are tightned and the crank journels are lubed with normal engine oil. I using NO.105 Engine assembly grease that I got from the machiene shop, and my crank cant be turned by gripping two rod journels by hand. Is this normal? The grease isnt real thick.....about half way between Vasoline and motor oil. could the slightly heavier grease cause this to happen, and what can I do about it? or do I need to do anything about it? The mains have been align bored.
thanks,
Mike

Good Guys Wear Bow-Ties
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RolngThun 07-24-2000 09:47 PM

Re: Should a newly installed crank be tight?
 
No, this is not normal. Loosen them one at a time to see if you can find a tight one. Then leave that one loose and retighten the others that you loosened and recheck easy turning.This makes sure there is only one too tight.
Also once you can turn the crank, turn it 180 deg from where it is now.Retighten bolts. See if it turns free for a 1/4 to 1/2 turn. If it does, you probally have two caps mixed up, or possible bent crank.
Those where quick checks without having to pull out the measuring tools.
If no clues where given from above, your going to have to mic each bearing and journal. Sometimes they mix a wrong bearing in a box. And sometimes a line bore job causes more trouble then what you started with.
Right now I'm guessing mixed up caps or a cap on backwards.
Can happen to anyone.


dave 07-24-2000 10:42 PM

Re: Should a newly installed crank be tight?
 
I will go out on a limb here, did you make sure the main caps were pointed in the right direction? Were the main caps marked before the engine was torn down? The main caps have a small arrow cast into them. The arrow cast into the main cap should point toward the front of the engine block (timing chain). If the main caps were not marked at the tear down, it's still possible to figure which main cap should go where. With the crankshaft and main bearings removed, install the middle main caps torqued to spec. Check / feel the mating points of both half circles. There should be a nice smooth mating between the top main cap and the block. It's possible you might have to swap a couple main caps to get the right combination. It's only takes one main cap that is out a couple thousands to make the crank tight! Then again you should only need to check the main caps if they were not marked during the tear down.
dave


RolngThun 07-25-2000 05:53 AM

Re: Should a newly installed crank be tight?
 
Another thing, since it has been line bored. It is not the orignal position of the caps that matters now, but rather the position of the caps when it was bored. Hopefully the shop had them in the orignal position when they did the job, but you can never tell what a machine shop can do.


**DONOTDELETE** 07-25-2000 06:45 AM

Re: Should a newly installed crank be tight?
 
I checked the direction of the caps, but didnt take them off yet. They are all in the right direction. If I do find one or tow that dont match up, would it have hurt the crank or bearings being tightned down like that? If I put my crank and bearings in another block and the crank spins freely than I know there is something in my new block, right? I have a 305 block, when I took the pistions and rods out of it the crank turned easily.
Is line boreing really often required? The first block I sent to the shop hadent spun any main bearings, but they said it would need line bored. didnt really make sense to me.
Thanks,
Mike

Good Guys Wear Bow-Ties
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dave 07-25-2000 08:57 AM

Re: Should a newly installed crank be tight?
 
Checking the bearings and crank in the 305 block is a good idea. It's more common to line "hone" blocks. Line boring is not as common. Line boring will remove about .010" metal from the main bearing caps, then the main caps are bored. Line boring will move the crankshaft closer to the the camshaft. Line boring a block will require a special undersize timing chain and gear set to correct the new line bored closeness of the crank and cam. Line honing will not remove much metal from the main caps, then the main caps are honed. It's common to line bore a block when the main caps are donated from another block. Seems it's common for some people to loose the main caps to there block, then a machine shop will need to line bore the mains to get the mix match of mains caps and block correct.
dave


**DONOTDELETE** 07-25-2000 01:57 PM

Re: Should a newly installed crank be tight?
 
I pulled the crank and bearings out and torqued the caps back on the block. When you run your finger around you can feel a place on each cap but the rear one where they meet the block. When you do this to the 305 you can feel none at all on any of them. the #2 cap is the worst. If I switch #2 and #3, you can still feel it, but not as bad. Is any "lip" at all acceptable? The rear upper bearing half also does not fully line up with the oil hole. It does on the 305 however. If it was line bored wold this be a problem? Also, if it was line bored, and the crank was closer to the cam, wouldnt it also be closer to the deck surface too? Do you have to wory about the pistions traveling too far up in the cylinder (speed pro hypertectic 17cc dish). Any Ideas on what to do??
I need at least 5 years of daily driving out of this engine (1st year of college).
Thanks a million for the help so far!
Mike

Good Guys Wear Bow-Ties
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RolngThun 07-25-2000 04:12 PM

Re: Should a newly installed crank be tight?
 
At this point I would carry that block down to the machine shop and let them look at it.
It sounds like a very poor job to me.Or they just had the caps in a different order.
This is why I don't like line boring. It takes a very knowledgable machinist. And the SBC rarely needs it.
If it is a bad job and they say they have to recut it, I would consider scrapping and starting fresh. Two cuts could lead into more trouble, especially if the deck was cut.
I would go with your instinct here, if you are feeling uncomfortable with a part of a job, then there is probally something wrong.
I would hope if the shop did do a poor job that they will do whatever it takes to correct it.
Keep us posted to what you find.


**DONOTDELETE** 07-25-2000 06:26 PM

Re: Should a newly installed crank be tight?
 
I re-arranged the caps so the "lip" isns as bad. But on all but one or two of the seams can you run your finger across and not feel anything. The ones that arent perfectly aligned have a lip that is still big enough to snag up a finger nail. The rods rod caps meet with no noticable seam, as do the mains of my 305. Im going to call several shops tomorrow and get other opnions as well before I go back to the one that did the work. Kinda makes you wonder what kind of balancing job they did? Do you guys have anything else to add. Am I correct in assuming that there should be absolutely no feelable seam where they meet?
Thanks,
Mike

Good Guys Wear Bow-Ties
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RolngThun 07-25-2000 07:42 PM

Re: Should a newly installed crank be tight?
 
In your case the joint should appear seamless. Being they are the orignal caps.
I did do a big block once where I took 4 bolt caps off a block I didn't care to use, and installed them on a 2 bolt case. Since there was a slight lack of meat doing it this way,a couple of the joints didn't appear to line up perfect.
But it worked just fine. This was a 8000 rpm race engine,and never had a bearing failure.
But like I said, in your case they should have come out perfect.



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