Chevy Cobalt Forum banner

Status
Not open for further replies.
1 - 4 of 4 Posts

·
Registered
Joined
·
750 Posts
Discussion Starter #1
So some of you may know that I have recently spun a connecting rod bearing or two and its time to fix it. My question is what size bearings do I need? I know that the main concern is oil clearance. I looked online and I found a specification of 0.0011-0.0027. I have purchased a set of plastigage to help determine the clearance I have. My concern is do I check the clearance with no bearing and then subtract oil clearance from the reading to get the bearing size? Or do I need to get a standard set of bearings first and use them with the pastigage to see if I an oversized bearing is needed and the size required?
 

·
Levee
Joined
·
3,210 Posts
I would get oem size bearings first. You test the plastigauge by putting the rods and bearings together and torque down to the crank with plastigauge between the bearings and crank

Sent from AutoGuide.com Free App
This is good info right here.

However, you need to look at the crank and rods first before getting any bearings. If they are NOT shiny like they are supposed to be, you need to not put the bearings in at all or you will just spin another one within minutes of starting the engine again. The crank surface and rod/rod cap surfaces need to be smooth for proper oiling and sliding of the bearing on the crank to keep the bearing from catching on it and spinning again.
 

·
Registered
Joined
·
750 Posts
Discussion Starter #4 (Edited)
Its been awhile but I finally have gotten around to figuring out what bearings I need. I got a set of plastigauge and some stock bearings. I started off with the green green plastic which i later figured out it can only measure up to .003 which is what closely matched the plastic after torquing it down. It looked a little bit smaller so i decided to do it again with the red plasti instead which measures bigger sizes. With this it measured .006 The book says the gap needs to be between .0011 and .0027. If my math is correct that would mean i would need to get an under sized bearing. They only come in .01, .02, or .03 and not 100% sure which one I need.

If I understand correctly:

.01 minus my gap of .006 = .004 which isn't within spec
.02 minus my gap of .006 = .014 which is within spec
.03 minus my gap of .006 = .024 which is wiithin spec

I would think that going with the .03 undersized would be the best so that if there is any future wear I would be within spec for a larger amount. However .02 miight be a better choice if some journals are not worn as much as the others. Can someone just verify that my thinking process is correct on this before I order the new set. Thanks
 
1 - 4 of 4 Posts
Status
Not open for further replies.
Top