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Is machining cam bearings acceptable?

  • No way, its ghetto auto

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  • Depends (please explain in the post thread)

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Discussion Starter · #1 · (Edited)
My machine says yes, its been a common practice of his to customize them, that the block races arent perfect and when the old cam doesnt fit, they enlarge the ID of the bearings. I called the vendor where I bought the enginetech bearings, they said no. I called another machine shop, they said they dont, but they dont bad mouth guys that do. He said that sometimes you have to torque the crank in before the cam spins right, esp on aluminum blocks, but this is all cast, right?

My guy said he had no problem figuring out the order, it wasnt an order problem.
Is it common for an old cam to not fit into new bearings?

Im also left to clean out the shavings, looks like some went down the balance shaft hole,
looks like the bearings were drilled with the block upside down when it should have been right side up. He says I can just blow it out, do you guys think that will be good enough or do I need to pull the balance shaft or even rewash the block?

Im about to go over it with my cheap set of mics, the cam inserts the same way from either direction, and I can feel a slight sideways movement, Is a person supposed to be able to detect a .002 gap by feel?
 

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No idea what kind of disaster recovery you are discussing halfway thru, but just pick a guy/method and go with it at this point.
 

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Discussion Starter · #3 ·
Ive been calling a few shops, asking whether its acceptable to bore cam bearings, so far nobody else seems to do it, one place says its 350 to line bore the races so that standard bearings work without any trouble, but I dont know if I can go that much. They said that even though precision bearings shouldnt normally be machined, just because its been done doesnt necessarily mean the bearings are shot and need to be replaced again.
 

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This process of installing cam bearings shouldn't be this difficult. When you buy a set of cam bearings for any given block, the bearings should fit in (somewhat snug). They generally are placed in the box they came with in the correct order of install. THAT PART MUST BE DONE CORRECTLY because all the cam bearings do not have the same deminsions. Like I said, the bearings come in a box with the correct order for instalation in that box. Don't mix these up so you can sustaine the correct order. Hope this helps.......... Jake(mr goodwrench). ONE last thing, when installing the cam, make sure all is clean and use plenty of good oil on the cam and it's lobes. PS, when installing new cam bearings, be sure to use the correct tool for proper cam bearing position(need to be sure the oil holes in the bearings align with the block area.....CRITICAL!! Hope some of this helps. Mr goodwrench(jake)..... When installing the cam shaft, do this gently so the cam bearings don't get nicked up......every little bit helps for a better job with. Some guys may use LONG bolts for cam install to keep the cam aligned with the cam bearings(these must also be correctly installed)....paralled with the cam. There is a cam bearign tool for proper and good alignment. I would suggest you use one of these cam bearing tool installer. This will help insure the cam bearings are correctly aligned and in correct parallel alignment with the block. Take your time and use a CAM BEARING INSTALL TOOL! One last thing, when installing the cam bearings(in the correct order), make sure the oil holes in the cam bearings are aligned to the oil holes in the block area so oil will actually do it's job thru these oil holes. THIS part can be critical......do this correctly(or pay a machine shop to do it for you if necessary). Best of luck and take your time to do this correctly......and get help if you are having issues.
 

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My machine says yes, its been a common practice of his to customize them, that the block races arent perfect and when the old cam doesnt fit, they enlarge the ID of the bearings. I called the vendor where I bought the enginetech bearings, they said no. I called another machine shop, they said they dont, but they dont bad mouth guys that do. He said that sometimes you have to torque the crank in before the cam spins right, esp on aluminum blocks, but this is all cast, right?

My guy said he had no problem figuring out the order, it wasnt an order problem.
Is it common for an old cam to not fit into new bearings?

Im also left to clean out the shavings, looks like some went down the balance shaft hole,
looks like the bearings were drilled with the block upside down when it should have been right side up. He says I can just blow it out, do you guys think that will be good enough or do I need to pull the balance shaft or even rewash the block?

Im about to go over it with my cheap set of mics, the cam inserts the same way from either direction, and I can feel a slight sideways movement, Is a person supposed to be able to detect a .002 gap by feel?
NO! if the cam bearings are the correct parts for your block, with a little oil the cam should slide in pretty easy but be carefull as you go from one position to another so you do not scratch up the new cam bearings. There is a tool to hold the camshaft in position parallel to the block while sliding it into the cam bearings. Do this part gently so you do not scratch up the new cam bearings. Some guys will use long bolts at the font of the camshaft to help keep the cam aligned with the cam bearings to help eleminate any cam bearing damage or scratches.....just go slow while turning the cam shaft by hand during install. Use plenty of oil on the cam and it's lobes. If you take your time it should go pretty easy. Pretty sure you will see all this as you progress with this process. Not rocket science, just take your time and try to be gental on the cam bearings............. Best of luck........ Mr Goodwrench(Jake)
 
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