Engine builder's, cam bearing surface ???

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C300

C300

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I think the Machinist/engine guy said he honed them after they were installed. just noticed that they were rougher than I'm used to. this one isn't too bad. i can catch a finger nail in the grooves left behind. #3 is really rough ! Is this usable ? I haven't seen them with groves this deep before. This is a 512 ci RB. will be getting a Hyd. roller cam, specs are aprox. 242/246 w/.575 and .591 lift. 1.6 hughes rockers. was their recommendations. just looked on Hughes web site and the list of cams is considerably shorter. hope it's still available ! Was about to build the short block, and saw this, thanks in advance, C300
 

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Are you sure that he didn't put that groove in there on purpose for oil flow???

It looks too uniform to me for it to be a "mistake"... especially so well centered on the bearing and the width looks consistant like they machined a little more clearance for oil flow...
 
he honed it so the cam fit/felt/measured good. He did it "on purpose ". it just seems a little aggressive. remove too much and it will flatten out. LOTS of pressure there. then oil will flow out and it's done. just not sure... could be super great... Hoping a shop guy can fill me in with some facts here ! how much is too much ?
 
If there is too much crush on the bearings , it's better to hone out the cam bores themselves , not the bearings, in my world what he has done is a no go unless you have no other choice.
 
From Mike at musclemotors
The real reason on why “my cam won’t turn”

For as long as I can remember, Mopar’s have been known for poor fitting camshafts. I even remember seeing a price sheet in the mid 80’s from a machine shop in Detroit that serviced the Big 3 specifying an additional charge for installing Mopar cam bearings. It even became standard procedure at Muscle Motors to test fit a cam before washing the block for final assembly. The standard solution has always been, “just carve on the bearings to make it fit”. While this mindset works it always bothered me. If it happens to you when you get your block back from your local* machine shop and want to put it together, you do what you need to do.

My problem solving nature never accepted the “just carve on them” solution (cure the problem, not the symptom!). I mean they make rod and main bearings within a few ten thousandths, why aren’t the cam bearings just as consistent (PS, they do make cam bearings just as consistent). So in a moment of clarity, I thought, if the bearings are being made correctly maybe I should check the block. I then started measuring the actual bearing bores in the block. This specification, by the way, is in every bearing book in every machine shop on the planet. What I discovered made everything I had struggled with for years make sense. Of the first 10 bocks I measured, not one of them was within spec on ANY bearing bore! Most were ½ to 1 thousands tight!!! To this day I have yet to measure a stock block that doesn’t need at least 2 or 3 housings opened up. The worst example was about 5 years ago when I measured a factory block that the #2 cam bearing was .003 tight!!!

Now the main reason most machine shops don’t measure this dimension is that even if they found something wrong, most shops don’t have the proper equipment to properly hone the cam bearing bores in the block! Due to stock blocks ALWAYS having some level of cam bearing fitment issues, our standard procedure at Muscle Motors is to hone ALL stock block cam bearing bores. This ensures if you get just a machined block or a short block from Muscle Motors, your cam will fit every time with no problem.

If you are having a block machined (at a shop of your choice) PLEASE insist that the shop measures (and corrects) the cam bearing bores BEFORE they install the cam bearings. This will save you time, effort, stress and the need to “carve on them to make ‘em fit……………….

Mike @ MM
 
The MM quote is right. But, since the cam bearings are fed very well, and there's not too much pressure on them, and it has five bearings to take that pressure- I never felt bad about carving on them. You DO NOT hone them. Honing stones break down under use. As they break down, if the surface being cut is hard,the abrasive goes into the oil as it's honed. If it's soft, the abrasive embeds in the material. So those bearings have crap in them. That's why cam bearing knives were invented when cams started being supported by bearings. I use a single edge razor blade to do mine. Cam should turn by hand (like using your fingers).
 
Thanks for all the replies. all were helpful and as correct as could be. was charged $55 for cam bearing install and like $27 for the bearings. I ALWAYS do my own. this time I asked to also measure up the cam and lifter bores since one of my boxes of micrometers disappeared in the last move(^%(^&($$#@!). namely the 3 federal bore gage sets and ID stuff. Anyway, when he told me he had to hone it, i assumed it was BEFORE the bearings were installed. I've done cylindrical, surface and internal grinding for a living. we had a sunnen hone. yes, I almost lost an arm many times...(for those in the know). we had installed a hoist over it for heavier things. opened up some overhead cam journals to except bearings. milled a bearing notch in too. but never honed a babbitt bearing. Moper, i agree, there must be all sorts of crap in-bedded in them. I didn't go this far to cut sharp corners. was reading another thread and someone commented to let the shops do it. not always... time bomb...:banghead:

Oh, this is my first BB mopar build. Thanks a million WILLIAM !!! I checked and line honed the circle track chevys i built after a tight one and tearing it down to re do it. here we go again. thought this was standard practice. guess not. I've heard of scotch brighting them for final fit, but not on a HP motor.
 
If all the bearings are tight, grinding down the cam journals is also another alternative. Bearing knifes are OK for removing high spots on bearings, but I don't fancy using one to correct a bearing with too much crush.
 
We size the cam mains in the block if they are on the low side, to the high side, and use Durabond performance cam bearings in every build we do. Cam goes in with about .001 of clearance on every journal...works every time!
Brian
 
I lost a engine in my mini van because of a spun cam bearing that shut oil off to the rockers.I would much rather hone the bearing for proper clearance than machine the bearing bore or the cam bearing surface. Scraping is to remove burr's from the installation and not to reduce the diameter.
 
ou812 said:
We size the cam mains in the block if they are on the low side, to the high side, and use Durabond performance cam bearings in every build we do. Cam goes in with about .001 of clearance on every journal...works every time!
Brian
Click to expand...

Spot on
 
E-Booger mentions in a 360 build that Mopar Action did, That mopar cam bearings are .003 tight, & standard practice is to use a bearing knife to fit the cam to the bearing.
 
mopuk368 said:
E-Booger mentions in a 360 build that Mopar Action did, That mopar cam bearings are .003 tight, & standard practice is to use a bearing knife to fit the cam to the bearing.
Click to expand...

Yeah, and standard practice for some people is to smash the crap out of something with a hammer, instead of using a press. Why?? because they don't own a press.
 
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