crankshaft .0025 from front to rear ?
 

is this acceptable? Just got all my parts back from the machine shop and after cleaning i started double checking
measurments. The gen IV crank measured from bearing 1-5
: 1=2.749 2=2.7485 3= 2.748 4= 2.748 5= 2.7465
Any thoughts thanks, troc

Re: crankshaft .0025 from front to rear ?
 

: 1=2.749 2=2.7485 3= 2.748 4= 2.748 5= 2.7465

Seems like a lot. You will need to mix and match shell/sets halves to get the .003 - .0035 needed. That is not uncommon. Make sure your measurement method is accurate. I always sanity check with plastigage during final assembly as well.

BT :cool:

Re: crankshaft .0025 from front to rear ?
 

Plasti- gauge gets a bad rap. i am pretty confident on my measuring, should have the plastic! thanks for the reply. I will doubl check tommorow then start mixing and matching halves

Re: crankshaft .0025 from front to rear ?
 

Troc,
The rear main is supposed to have almost .002" more clearance than the rest. As far as the diffference you are getting in the others, it is pretty normal for a stock crankshaft. You can mix some bearings if you want. Thats why we generally regrind every crankshaft in engines that we build. That is the only way to know they are correct :)

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Re: crankshaft .0025 from front to rear ?
 

thanks bill, Is that because more load is occuring at the rear,so that allowance is made ? thanks again it is much appreciated , troc

Re: crankshaft .0025 from front to rear ?
 

Troc,

I dont really know the answer, but if I had to guess I would say it was to pass more oil through the bearing, maybe to get to the thrust surface ? I may have to see what I can find out and report back .... inquiring minds must find the answer :)

Bill

Re: crankshaft .0025 from front to rear ?
 

thanks again bill, i will do the same on my end
Cort

Re: crankshaft .0025 from front to rear ?
 

Lets us know what you find out Bill. I always shoot for .003 on 1-4 and .0035 on the main. I would think .005 on the main would be excessive. I have had oil temp problems in the past from time to time and often wondered if I wasn't tight in the main.

BT :cool:

Re: crankshaft .0025 from front to rear ?
 

talked to machine shop today,same explanation as you Bill. rear is usually under .001-.002. larger bearing surface to support crank/oil for thrust surfaces. he did say he would not
run clearances greater than .035 in a bbc. I bought a set of .001 over bearings and split with std. and got my .025"
Thanks again Bill
cort :D

Re: crankshaft .0025 from front to rear ?
 

Cort,
That was the same explaination I got from the guys at the AERA www.aera.org Larger bearing surface and more load.

Bill