main bearing clearances

951 Blackplanet

New Member
Joined
Apr 20, 2006
just got my crank back today and i was checking my clearances and it spece'd ot to be .0005.i told the machine shop i wanted .0015,so he said he would cut it .0085.the gm manual states .0003-.0018.the crank does spin when it is tightened down but not by hand,i have to turn the balancer nut...any input would help alot.
 
Run minimum .0015-.0018 and you'll be fine.

Non-Buick shops can get you into trouble.

I wouldnt run .0008 Way too tight

Ohh.. crank better spin like butter.. nice and easy.. or you'll trash the motor. Better have the registers checked. May need to be line-hone'd a tad.. that would give you some clearance as well.

If it catches, or you cannot spin it after all was TQ's down.. you have issues that need addressing.
 
Are these standard bearings or has it been cut .010? What does the main journals measure out to? If this is a stock rebuild then i would shoot for .0015-.0018 clearance. DON'T USE plastigage. It is crap. beg borrow or steal a dial bore gauge and micrometer to check the clearances. Good luck. jeremy
 
crank has been cut .010,journals mic out to be 2.44915 i looked at the bearings and you can see where they have been riding on the bearings.what should i tell the machine shop i need the journal to be?also im using clevite bearings and checking all clearances with a mic and boregauge.
 
I have used plastigauge for years with no issues. Just my .02

and you've been lucky, i wouldn't waste my money on plastiguage, have it measured w/ the proper tools by someone that knows what they are doing, and using a dial-bore gauge on the bearing with it installed in the block/rod isn't the most accurate way either, b/c the spring tension of the gauge will actually gouge the bearing some, it best to us a pair of tubing mics on the bearing, mic the crank, and use a dial bore gauge on the mains/rods and then figure the tolerance stack on paper.
 
This is not a job for you to do as i found out. Bring it back to the shop and have him either cut or polish the crank and rod journals, or use a different bearing. It should turn nice by hand when torqued. I went with .0023-.0026 which is on the loose side but it is a race motor.
 
I have used plastigauge for years with no issues. Just my .02

Every time I have verified Plastigage with mics and bore gauge...It was RIGHT-ON.

I do not know what is going on for people to keep claiming the stuff is junk - maybe something moves before disassembly and reading???
 
I have a few TR friends who decided to assemble their short block.
If EVERTHING is correct, it should go fine. Are you willing to roll the dice? My advice is "Do yourself a favor".

1. Know your limitations.
2. Find a reputableTR engine machine shop.
3. Pay someone to get it done if you lack the tools, true indepth knowledge and/or experience.

My $0.02.
Good luck!
 
I have a few TR friends who decided to assemble their short block.
If EVERTHING is correct, it should go fine. Are you willing to roll the dice? My advice is "Do yourself a favor".

1. Know your limitations.
2. Find a reputableTR engine machine shop.
3. Pay someone to get it done if you lack the tools, true indepth knowledge and/or experience.

My $0.02.
Good luck!

Hey you told me the same thing when i built my motor HAHAH...... "Good call!
(in Clint Eastwood Voice): "A man got to know his own limitatons".

Edit;
No offense intended.
That is why I paid a *REPUTABLE* machine shop experienced in TR building.
I could not afford another mistake."

You were definitely right!!! I had the shop take care of it. Cost me 1200 since i had a gurdle and 4 main caps that all needed fitment.
__________________
 
Hey you told me the same thing when i built my motor HAHAH...... "Good call!
(in Clint Eastwood Voice): "A man got to know his own limitatons".

Edit;
No offense intended.
That is why I paid a *REPUTABLE* machine shop experienced in TR building.
I could not afford another mistake."

You were definitely right!!! I had the shop take care of it. Cost me 1200 since i had a gurdle and 4 main caps that all needed fitment.
__________________

LOL.
That is one my favorite movie sayings ........
 
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