FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: dozz302 on February 22, 2021, 02:36:28 PM
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Hello, it is my understanding that cam bearings generally don't wear out unless they have megga miles on them. Is there an easy way to check them other than an inside micrometer. (I don't have one) I do have a regular micrometer though. Or just stick a cam in and feel for play? Thanks
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You'd use a bore gauge on the bearing itself and a mic on the journal. For the most part, if this is a new build, then your primary consideration is does the cam turn freely with no drag or binding anywhere in the rotation? If the cam turns freely, then you've done about as much as you can do. If the cam binds, then you see if you have a cocked bearing or if the bearing needs a shave. Giving the cam a wiggle tells you nothing even if you highly instrument it.
The reason cam bearings don't get the same fastidious attention as main and rod bearings is that there's not much you can do if the bearing isn't right other than replace it and see if the replacement works better.
If this is an older build, then the primary indicator of worn cam bearings is low idle oil pressure and a little less at higher rpm. It's not really the end of the world as long as your mains and rods look okay. Most of the time, low oil pressure is oil going past the cam bearings.
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For what it's worth, I check cam bearing clearance like I check main/rod bearing clearances. On really high end engines with lots of rpm and spring pressure, I've found it to be imperative to make sure there's adequate clearance.
I do use a mic and a bore mic. If the clearance is tight and I know there's not an issue with the bearing install, you can polish the cam journals down and get sufficient clearance.
I've never really had an issue with having too much clearance on a new build, but I've seen issues with not having enough. I use the same general bearing clearance rules of thumb that I use on mains/rods....an .001" of clearance per inch of journal diameter.
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So if you have 2.2 journals like the stroker cranks have (BBC) journals then what would the clearance be.
While we are at it whats the crank clearances. Dont want to hijack post but that would be .0022 I thought that was tight.
If you could advise that would be greatf
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So if you have 2.2 journals like the stroker cranks have (BBC) journals then what would the clearance be.
While we are at it whats the crank clearances. Dont want to hijack post but that would be .0022 I thought that was tight.
If you could advise that would be greatf
It depends on the application and the bearing.
On a typical street build with uncoated bearings, I will usually aim for .0022-.0025 on the rods with a BBC journal and .0028-.003 on the mains.
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Hello, it is my understanding that cam bearings generally don't wear out unless they have megga miles on them. Is there an easy way to check them other than an inside micrometer.
Just replace them! Unless this a an engine of frequent refreshing, but in that case even still, they're cheap, reasonably simple, or inexpensive to contract their replacement, and as with any bearing even if not showing noticeable frictional wear or surface reduction they can suffer from fatigue at which point they will suffer from fissures and delamination of the overlay. ;)
This is particularly a concern with the relatively narrow load bearing surface presentation of the FE coupled with greater than the O.E.M.s' loads inflicted due to more aggressive aftermarket cams, greater spring pressures and other valve train changes. :)
Scott.