cam or gears?
#19
Re: cam or gears?
Cam bearings are a bitch to replace and better left to a machine shop. The way i've usually seen them installed is cool them in a fridge for a while to contract then tapping them into place with a bearing driver. Some differ in methods but this one has always worked from what i've seen. But you have to make sure the mains are straight and that the bearing is installed at the right depth in the journal.
Usually when you spin a bearing it's best to replace all the bearings (basically a rebuild) and make sure all the oil passages are clean. Spinning one puts TONS of small metal shavings through the engine and scores other bearings and damages the oil pump. Not a pretty or cheap situation to be in unless you have money handy to fix it.
I may seem a little paranoid about it, but i'm not a stickler for suggesting a risky mod in your situation. If you had really low miles or a fresh rebuild with new bearings, i'd say go for it in a heartbeat. The thing with putting a fresh cam inside old worn bearings is that the bearing surface can become out of round. Which is fine and dandy with the cam that ran in those bearings since new, since the contact surfaces have worn to accomodate eachother and all the forces are distributed equally. When a new cam is set in these bearings, the cam's surfaces might not be completely flush with the old bearing's and this can cause the forces to become concentrated in some areas. Which increases the tendency for those areas to heat up to the point where they begin to breakdown and "grab" at the cam. Which is one way how it can spin out.
Usually when you spin a bearing it's best to replace all the bearings (basically a rebuild) and make sure all the oil passages are clean. Spinning one puts TONS of small metal shavings through the engine and scores other bearings and damages the oil pump. Not a pretty or cheap situation to be in unless you have money handy to fix it.
I may seem a little paranoid about it, but i'm not a stickler for suggesting a risky mod in your situation. If you had really low miles or a fresh rebuild with new bearings, i'd say go for it in a heartbeat. The thing with putting a fresh cam inside old worn bearings is that the bearing surface can become out of round. Which is fine and dandy with the cam that ran in those bearings since new, since the contact surfaces have worn to accomodate eachother and all the forces are distributed equally. When a new cam is set in these bearings, the cam's surfaces might not be completely flush with the old bearing's and this can cause the forces to become concentrated in some areas. Which increases the tendency for those areas to heat up to the point where they begin to breakdown and "grab" at the cam. Which is one way how it can spin out.
#20
Re: cam or gears?
so replacing the bearings usually requires pulling the motor and pulling the whole engine apart and sending the block to a machinist?
i have to admit that does seem pretty scary. i have 71000 miles on my car, is that definate "worn bearings territory"?
i am without a doubt going to put a cam in my car eventually(its seeming less likey that is going to be this next mod) but its definately going to happen so i'm going to have figure out all this eventually, any good books on this stuff that i could start reading? thanks again for the advise
i have to admit that does seem pretty scary. i have 71000 miles on my car, is that definate "worn bearings territory"?
i am without a doubt going to put a cam in my car eventually(its seeming less likey that is going to be this next mod) but its definately going to happen so i'm going to have figure out all this eventually, any good books on this stuff that i could start reading? thanks again for the advise
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10-31-2016 11:09 AM