I dont usally post here on the dentside forum, I am helping my brother inlaw biuld a 302 v8 from a 79 F100,my question is the camshaft rear bearing was to tight so I took the blook back to the machine shop and they honed all the cam bearings to make the cam fit,Is this an acceptable prosses, bearings have a lot of scratches or is this a hack job. any advice is aprisiated thank in advance



TASBOJ..............................

 

If the machine shop line honed the cam bearings, that's an acceptable practice, in fact on the old Ford Y block, that was necessary. However if they just scraped the rear cam bearing to clearance it then I wouldn't accept that.
Honing shouldn't leave scrape marks or grooves, it should be a smooth cross hatch pattern similar to a honed cylinder wall.
Can you post any pictures?

 

Cam bearings shouldn't need to be honed... the babbit layer is already thin.

I'd check that camshaft and its journals.

 

I dont have a camera it brokedown sorry, They honed the first 4 from the front not the rear,It looks like they use a corse honing tool and they have grooves that catch my finger nail, not a criscross like cylender bores that are very fine.Plus I can slide a .003 filer gauge in #2,3,4 journals I'm also concerd about low oil pressure.I read this on the web(When fitting aluminum cam bearings, it's important to allow sufficient bearing-to-camshaft clearance, since the harder aluminum alloy bearings won't wear in as rapidly as babbitt bearings to make their own clearance. Minimum clearance should be 0.002 inch for stock engines and 0.003-0.004 inch for high-performance engine)

I read this about honing babbit cam bearing with a stone. (If cam fit is too tight, bearing material can be removed by reaming. Schaerer says that honing bearings to size is not recommended, because honing stone grit can easily be trapped in the bearing surface, and its presence there can lead to premature camshaft journal wear.)

Here is the link where I read it.Cam Bearing And Installation - Rod & Custom Magazine

thanks for your input guys I will take the bloock back will see how it goes and I will post back with the out come.

 

Here's what I would do in your situation. This is just advice as to how I would handle this situation, you decide if it's right for you. But what I would do is do some research for a local reputable machine shop. Or even and engine build shop. Just make sure you do enough research that you feel confidant that they will give you fair honest evaluation. Then go from there. My fear is that maybe this machine shop messed up the line honing process of the block. And there "fix" for this is to do a butcher job of clearanceing the bearings to fit the cam. If that's the case that engine will be a ticking time bomb waiting to explode.

 

Update I spoke to the owner of the shop his a very nice person, He apologized and said he will make things right. The guy that worked on the engine block did not check the bearings for clearance with the new camshaft,So wen I took it back the first time he did a hack job trying to fix it,but the boss was not aware of the finished product, so new bearings are going in and he personally will check before I'm called to pick it up.


Thanks you all for your advice and fast responce.


TASBOJ........................................

 

That's great news. But I think I'd still have another shop check it afterwards just to make sure things are good. But that's just me.