trying to put motor together, crank is hard to turn

Old 04-28-2009, 07:03 PM
  #1  
motorobb625
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Default trying to put motor together, crank is hard to turn

SBC . put the crank, rods, and new bearings all in. fresh from the machine shop. I noticed it is hard to turn about half way around. took the rod caps off and noticed some bearing wear already showing. prolly only turned it 8 turns just playin around. is this normal? should it turn easliy all the way around? yes I did use assembly lube. WTF
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Old 04-28-2009, 07:41 PM
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MEMRACING62
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DID YOU MIC CRANK PRIOR TO ASSEMBLY? CHECK CLEARANCE? http://www.plastigaugeusa.com/
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Old 04-28-2009, 07:44 PM
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bowhay
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x2
if u didnt put some plastiguage to it and make it had good clearence that would explain it
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Old 04-28-2009, 08:32 PM
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zipper06
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Not normal at all, there could be a number of issues. Crank not turned round, not to size, or rods could be out of round. An assembled short block, sm/blk should turn over at about 20lbs torque with all new bearings, rear main seal and rings. in fact the last b/blk i assembled turned over at 20lb or less.

JMO

Zip.
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Old 04-28-2009, 09:26 PM
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Tod74
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STUPID QUESTION BUT HERE GOES....

Did you make sure not to mix up any rod and or main caps? Also..if your crank has a large fillet radius and you do not have chamfered bearings OR you Do have chamfered bearings and you mixed up the upper and lowers, it will do that.
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Old 04-28-2009, 09:32 PM
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dparker
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Originally Posted by Tod74
STUPID QUESTION BUT HERE GOES....

Did you make sure not to mix up any rod and or main caps? Also..if your crank has a large fillet radius and you do not have chamfered bearings OR you Do have chamfered bearings and you mixed up the upper and lowers, it will do that.
X2 on what todd said. Did the crank spin easily without rods and pistons?
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Old 04-28-2009, 09:37 PM
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signsbyesa
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yea should feel and turn smoothly, check size on mains with just
bearings and then check the size of the crank, same with rods,
torque them down with bearings only, and some plastigauge, take your
time and double check the journals, i used clevite and king bearings
w/o a problem, check to see if you need chamfered bearings,
good luck :wink:
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Old 04-28-2009, 09:39 PM
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ashbros
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If clearances check out ok and you did not mix up the connecting rod caps,
how bout putting a screw driver between the main journal and crank counter weight, applying a tiny amount of pressure before sunggin down the main caps, then snug them down while pressure is applied? then begin torque sequence. I usuall do this on 3 & 4th main caps. Seems to work every time.
Also check your end play clearances
Are Maincaps facing front of crank correctly?

Sorry, Gotta Ask.
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Old 04-29-2009, 04:35 AM
  #9  
hink
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Also check for run out as the crank may not be straight.
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Old 04-29-2009, 05:12 AM
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chevynovaman
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I HAD THAT PROBLEM ONCE, MY SHOP TEACHER NUMBERED THE MAINS FROM THE BACK OF THE MOTOR, INSTEAD OF THE FRONT. MY CRANK WOULDNT TURN AT ALL... MAINS WERE ALL BACKWARDS... WE GOT IT STRAIGHTENED OUT THOUGH...
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