what rod bearings and main bearings to buy???

95lsteg

New Member
i always have wondered what rod and main bearings to buy for my gsr block. i have no idea what size to buy. can anyone explain to me why they are different sizes and why it matters?
 

dc2GS-R

Super Moderator
You'll be fine with standard size.
I wouldn't say that is a guarantee. Personally I'd measure it first to be sure you end up with the proper tolerances.
 


dc2GS-R

Super Moderator
Measuring to find out the proper size bearing to use. You would need to measure the OD of the rod journals and the ID of the rod ends using a micrometer. Or you could use plastigauge as well.
 

95lsteg

New Member
Measuring to find out the proper size bearing to use. You would need to measure the OD of the rod journals and the ID of the rod ends using a micrometer. Or you could use plastigauge as well.
okay now i understand. usually is the standard size the best?? why would oversized be used on a factory rod?? (sorry im new to this building motor thing)
 


dc2GS-R

Super Moderator
The factory size should be fine if the crank or rods have never been turned or do not have excessive wear. But I think it's just a good idea to be damn sure before you build an engine around an assumption.

It may seem like a waste of time if the stock size turns out to be what you need, but it would be ten times worse if you built the engine and it has rod knock or spins a bearing.
 

95lsteg

New Member
The factory size should be fine if the crank or rods have never been turned or do not have excessive wear. But I think it's just a good idea to be damn sure before you build an engine around an assumption.

It may seem like a waste of time if the stock size turns out to be what you need, but it would be ten times worse if you built the engine and it has rod knock or spins a bearing.
well if i went oversized bearings, would it shave off the oversize and kinda make a custom size bearing... like when the crank spins around the tight bearing wouldnt it just loosen til its fine.. (confusing to understand prolly)
 

dc2GS-R

Super Moderator
That's bad. You don't want to do it like that. You want to measure them to get the correct tolerances. You need to find the happy medium of tolerances. If they are too tight the could score the crank and/or bearing and possibly spin a bearing or seize up. If they are too loose, you will have rod knock and potentially lead to a spun bearing.
 

95lsteg

New Member
That's bad. You don't want to do it like that. You want to measure them to get the correct tolerances. You need to find the happy medium of tolerances. If they are too tight the could score the crank and/or bearing and possibly spin a bearing or seize up. If they are too loose, you will have rod knock and potentially lead to a spun bearing.
okay gotcha well the guy just told me the crank was in mind condition, but ill measure and check. what measurements am i lookin for
 
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