Fourth Rebuild

 

  

 

      (Updated: 23 Mar 2008)

 

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Human beings must have action; and they will make it if they cannot find it.

-- Albert Einstein

 

   

 

26Oct06   Why am I going through a partial rebuild?  Even after the last total rebuild, my 383 stroker motor STILL uses about 1 quart of oil every 500 miles...  AND it's running WAY too rich.  I know the main and rod bearing clearances are really wide.  Theory has it that the wide clearances are allowing too much oil to contact the cylinder walls, thereby overwhelming the piston rings ability to prevent the oil from entering the combustion chamber.  My goal is to tighten up the bearing clearances and see if this will slow the oil consumption.  The plan is to remove the crankshaft without removing the heads and pistons!

 

I've had I don't know how many people sware up and down that the high oil consumption is being caused by my high volume oil pump...   regardless that I'm running a standard pressure spring at the factory 40 psi pressure.  So, I'm going to replace the Melling M-55 High Volume pump with a Melling M-155 standard replacement unit.  Well see...

 

  27Oct06    Welp, I decided to go for it--  again.  Backed the car into the garage and began disassembly.  
  29Oct06    Motor is out of the car.  Pulled the crankshaft with the pistons and rods still in the block.  Measured the main and rod bearing clearances.  Here's what I found:  

         

 

 

crank outside dia.

bearing inside dia. Fed. Mogul (Std.)

clearance bearing inside dia. Fed. Mogul (.010)
  measured spec. measured calculated spec. measured
             
crank main journal #1 2.448 2.4484 - 2.4493 2.453 .005 .0007 - .0021 2.443
crank main journal #2 2.448 2.4481 - 2.4490 2.453 .005 .0009 - .0024 2.443
crank main journal #3 2.448 2.4481 - 2.4490 2.453 .005 .0009 - .0024 2.443
crank main journal #4 2.448 2.4481 - 2.4490 2.453 .005 .0009 - .0024 2.443
crank main journal #5 2.448 2.4479 - 2.4488 2.453 .005 .0010 - .0027 2.443
             
rod journal #1-8 2.099 2.0990 - 2.1000 2.104 .005 .0013 - .0035 2.093
             
             
  I spoke with a tech rep at Speed Pro to find out what the inside diameter of main and rod bearings are.
  Below are the numbers I was given over the phone.  As you can see, they aren't even CLOSE to the  
  numbers I actually measured!  Curious...  
             
Speed Pro bearings (.010)   Speed Pro specs.        
139M-10 (mains)   2.4579 - 2.4588        
8-7100CH-10 (rods)   2.1090 - 2.1100        
             

 

  3Nov06   Took the crankshaft to Kim Barr at Kim Barr Motors to have it turned so I can use the .010 size bearings I bought.  To my dismay, I learned turning this crank is going to be a BIG problem!  The solution?  I'm going to use a Clevite 77 bearing .002 oversize and have the bevel machined into the edge of each bearing so they will be compatible with the radiused crank rod journals.    
  7Nov06   Picked-up the crank and bearing set from Kim Barr today    
  8Nov06   Assembled the rotating assembly to measure bearing clearances.  Here's what I found:    

 

 

crank outside dia.

bearing inside dia. Clevite 77 (+.002)

clearance  
  measured spec. measured calculated spec.  
             
crank main journal #1 2.448 2.4484 - 2.4493 2.449 .001 .0007 - .0021  
crank main journal #2 2.448 2.4481 - 2.4490 2.449 .001 .0009 - .0024  
crank main journal #3 2.448 2.4481 - 2.4490 2.449 .001 .0009 - .0024  
crank main journal #4 2.448 2.4481 - 2.4490 2.449 .001 .0009 - .0024  
crank main journal #5 2.448 2.4479 - 2.4488 2.449 .001 .0010 - .0027  
             
rod journal #1-8 2.099 2.0990 - 2.1000 2.1002 .0012 .0013 - .0035  
             
             

 

 

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