minimum bearing clearances

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rjustman

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Nov 29, 2012
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I have been looking high and low for this.i have found a few threads giving the MAX clearance but nothing giving the minimum. ive looked in manuals, as well as google. I am assembling my motor and measured the mains with plasti gauge. im at

#1.003
#2.0015
#3.0015
#4.0015
#5.001
#6.0015
#7.0015

what is to tight? machine shop told me to play around with the bearings to find some arrangement that will make em all about even. but looking at what I have only #1 and #5 look like they will get me anywhere switching them around.

this is all on a 12v and if it needs to be moved to the 94-98 section I apologize I just posted here thinking that maybe everyone with the different years could benefit from it.

thanks

Richard
 
What are you going to be doing with the truck? How many RPM's?


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It'll be a daily driven truck..no competition.street truck,towing,playing.just an everyday truck that depending on the situation could possibly see as much as 4k rpms..I try to frequent the local dyno events,and might possible run down the track on the run what you have nights ..
 
So I'm waaaay to right..dunno if it makes a difference but machine shop put a Teflon type coating on all the bearings..I didn't ask him to he just did
 
That sounds to tight. Just trying to remember a couple stock rebuilds i did thet were in that range i gave. Do you have the old stock bearings? I always use a bore gauge. Check it with the old bearings against the new. That will tell you roughly what it was stock. Do you know someone who has one.
 
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I don't..I don't have old bearings either..I tossed em after I disassembled this motor..
 
I don't use plastigauge. Never have but you aren't supposed to double that number are you?
 
I dont know..I've never used it either..if so I have another problem..that would put me at .006 on #1
 
rjustman said:
I dont know..I've never used it either..if so I have another problem..that would put me at .006 on #1
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Whatever the plastiguage measures out to is correct, make sure you are using the correct size. Pretty sure the color we used was red, but it may vary with other brands


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There was green and red in same package green from.001-.003 red from .003-.006 I believe I'd have to look at the package..machine shop said everything was measured to where I could just put it together..just for sh!ts and giggles so I have all the build specs for later on if I ever needed anything
 
You don't double the plastigage readings. Just measure them. Should correspond to your bearing and journal measurements very closely, so if there is a discrepancy there, start redoing it all.

If he put a coating on the bearings, I'd look for a different set of bearings for it.
 
So bottom line it sounds like they're to tight..what is the minimum clearance y'all would run.
 
I usually go by the 1-1.5 thousandth per inch that Disturbed stated.
 
The clearances are pretty tight for mains. I'd switch to uncoated bearings. Not much point in coating main bearings anyway. It does help with rod bearings. And if you have clearance issues, you only really need to coat the top bearings.
 
That was an option that my machinist said was to take 600 grit paper and take coatings off just be sure not to get into,metal..so take coatings off the bearings with oiling holes is what your saying..
 
I would just send them back to the machine shop and have him get you stock set. I wouldn't touch the bearing with sand paper.
 
Like he said, I wouldn't sand them.

Coatings are about .0005, so you'd have to get all of it off to pickup enough clearance. Just get him to replace them.
 
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