trying to put motor together, crank is hard to turn

Old 04-28-2009, 06:03 PM
  #1  
motorobb625
Junior Member
SHOW GUEST
Thread Starter
 
Join Date: Jan 2008
Posts: 8
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
motorobb625 is offline  
Old 04-28-2009, 06:41 PM
  #2  
MEMRACING62
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Location: orland pk il
Posts: 2,399
Default

DID YOU MIC CRANK PRIOR TO ASSEMBLY? CHECK CLEARANCE? http://www.plastigaugeusa.com/
MEMRACING62 is offline  
Old 04-28-2009, 06:44 PM
  #3  
bowhay
Senior Member
EXPERT BUILDER
 
Join Date: Nov 2008
Posts: 263
Default

x2
if u didnt put some plastiguage to it and make it had good clearence that would explain it
bowhay is offline  
Old 04-28-2009, 07:32 PM
  #4  
zipper06
Senior Member
RACING JUNKIE
 
Join Date: Jan 2006
Location: La.
Posts: 2,890
Default

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.
zipper06 is offline  
Old 04-28-2009, 08:26 PM
  #5  
Tod74
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Posts: 4,137
Default

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.
Tod74 is offline  
Old 04-28-2009, 08:32 PM
  #6  
dparker
Senior Member
RACING JUNKIE
 
Join Date: Jun 2003
Location: Hobbs, NM
Posts: 842
Default

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?
dparker is offline  
Old 04-28-2009, 08:37 PM
  #7  
signsbyesa
Senior Member
RACING JUNKIE
 
Join Date: Feb 2004
Location: san antonio, texas
Posts: 1,233
Default

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:
signsbyesa is offline  
Old 04-28-2009, 08:39 PM
  #8  
ashbros
Senior Member
RACING JUNKIE
 
Join Date: Nov 2004
Location: St. Louis, Missouri
Posts: 661
Default

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.
ashbros is offline  
Old 04-29-2009, 03:35 AM
  #9  
hink
Senior Member
EXPERT BUILDER
 
Join Date: Nov 2003
Location: NORTHEAST
Posts: 290
Default

Also check for run out as the crank may not be straight.
hink is offline  
Old 04-29-2009, 04:12 AM
  #10  
chevynovaman
Senior Member
SENIOR BUILDER
 
chevynovaman's Avatar
 
Join Date: Sep 2008
Location: CENTRAL WISCONSIN
Posts: 114
Default

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...
chevynovaman is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -