Joe, what if the original fits properly and the new one doesn’t which was the original question.
Very early in my training and watch my dad with a bearing scraper I learned how to fit and scrape a Babbitt style bearings. Thats why grooving a journal was so interesting.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Thanks to Joe for chiming in and setting the record straight.  Never modify the journals on a camshaft with ‘cutting’ grooves that is intended to be run within an engine.
 
In the event an original camshaft fits freely into the cam bearings but a replacement camshaft does not, the problem is likely in the replacement camshaft.  This is assuming that a set of undersize cam bearings are not in the block and the original camshaft had had its journals reground accordingly.  That particular scenario was a common practice back in the day but not so much today.  Back to the replacement camshaft not fitting, then simply mic the journals and compare those sizes to the original.  Then check the replacement camshaft for being bent.  That can be performed in a pair of V blocks and a dial indicator.
 
My bad for not clarifying that ‘cross’ grooving a camshaft is only performed on old or throwaway camshafts for the purpose of removing babbit from cam bearings that are too tight for the camshaft that’s being used to freely turn.  Under no circumstances should the camshaft that’s being installed within engine for final use have those ‘crosscut’ grooves in them.  Not only will the existence of those grooves in a running camshaft continue to carve out bearing material, they are an additional path for oil pressure between the bearing and journal to be relieved.  But bearing material removal will more than offset those other problems very quickly.  Treat camshaft journals just like crankshaft journals.
  
On a different but related topic, several years ago I had tried to get CWC to make one hundred cam blanks with no oil groove on the center journal.  By doing this, the center camshaft bearing would not wear out as quickly by permitting a dynamic oil wave to be present as is on the other four cam bearings.  In a center grooved camshaft application, the center cam bearing in a Y always exhibits more wear than the other four.  Cross drilled camshafts on the other hand do not exhibit as much wear issue on that same bearing location.  The CWC order was just too small and there was no interest on their end in doing that.
 
I have welded up that oil groove on the center journal and reground that journal to spec in a crankshaft grinder and those camshafts are still in service today.  Until one of those engines is torn down for inspection, I can only assume that the bearing wear on that center journal has indeed been minimized to the same level as the other four.  For the non-grooved center camshafts, the oil for the top end of the engine comes from a machined groove in the block behind the cam bearing much like is being done on the FE engines.

Lorena, Texas (South of Waco)

ted what would happen if you just turned the cam bearing until the holes to the heads were blocked of.drilled a new hole to feed the bearing would the groove still wear the bearing.

Excuse the lengthy post again as there’s a lot of information to be shared here.
 
Darrell.  As you point out, it is the groove in the center camshaft journal that’s the root of the problem and not the other two holes in the bearing that permit oil to be fed to the top of the engine.  Even if the two additional holes in the bearing were not there, that groove is allowing some of the oil pressure to bleed off at the top of the journal and is preventing a proper oil dynamic wave from being created at the bottom of the journal.  The wear characteristics at the center cam bearing with a cross drilled camshaft are much more reduced than what is seen with the grooved camshaft journal.  The engineers at Ford must have wrestled with this as the 1954 and 1955 engines used cross drilled center journal camshafts and went to the grooved camshafts in 1956.  Comes 1963, the cross drilled camshafts are back for the Ford pickups and trucks.  If it's any consolation to the cross-drilled camshaft design, I've pulled apart several of those engines that were very high mileage with some being over 300K miles and they were still oiling the top ends of the engine just fine.  Good oil and regular changes go a long way in keeping the wear to a minimum on these engines.
  
Complicating that cam bearing wear issue is the latest crop of cam bearings.  They are softer than the originals and just wear or ‘seat in’ much more quickly.  The Engine Tech CC-508 bearings made in South America are a harder material than found in the Sealed Power and Durabond cam bearings for the Y.  If I know I’m going to have a cam bearing issue such as with a 312 with crooked cam tunnels, then the Sealed Power or Durabond bearings are definitely easier to ‘carve’ on in which to get the camshaft to freely turn.  For the 272 and 292 engines that are not going to present an issue, then the Engine Tech cam bearings are the bearings of choice.
 
I do have a machined bar here to check for cam tunnel alignment.  That bar when inserted from each end of the engine will point to the exact areas of the cam tunnel that are going to give the most trouble.  With that information, the cam bearings can be altered appropriately before they are installed in the engine thus speeding up that process considerably.  I have had some 312 engines so bad on that alignment that I simply re-bored the cam tunnel hole to the 1954 hole size and then made new cam bearings from scratch using bearing bronze.  On those bearings, I only put in one hole for the cam journal with the oil supply to the top end being supplied by a machined groove in the center cam hole.  The 1954 cam bearing hole size is used so that the 1954 rear cam plug can be used.
 
For the 427 FE side oiler engines, Ford went to a grooved camshaft to provide oil to the top end.  On those engines it was the #2 and #4 journals.  This was done to reduce the oil flow to the top end and thus supply more oil to the bottom end.  Unfortunately this brought up the same issue of the cam bearing material pressing into the camshaft grooves in the #2 and #4 journals and shutting off all the oil supply to the top end.  When a roller camshaft is used with the much higher valve spring pressures, cam bearing issues came to the forefront almost immediately.  On a flat tappet camshaft, it just took a little bit longer.  On those 427 side oiler engines, I simply machine a groove behind the cam bearing and use a conventional (non-side oiler set) cam bearing set to eliminate that issue.  If needing to restrict the oil to the top end, a restrictor at the top of the head under the rocker arm stand fixes that.
 
In a perfect world, the oil supply to the camshaft journals would be located at the four or five o’clock position when observing this from the front of the engine rather than at the six o’clock position that those bearings are normally installed at.  Ford actually started doing that 4:30 o’clock positioning in 1972 with the FE engines after fourteen years of installing those bearings simply at the six o’clock position or aligned at the main bearing feed hole.

Lorena, Texas (South of Waco)

Excellent information Ted and very much appreciated. This is better than sitting by the fire on a cold winter/s night reading your favorite technical publication. ......


64F100 57FAIRLANE500

Ted, I looked at EngineTech's website and found the CC 508 bearings are listed for '56 and '57 engines, no other years listed. Are there differences between those 2 years and earlier/later engines? I wouldn't think so, but Ford has been known to do strange things on a seemingly random basis. I have a '55 Merc 292 that has the known oiling problem to the passenger side rockers. I've had the rocker assembly off and squirted carb cleaner down the feed hole in the head. The carb cleaner seemed to go through the passage with little resistance. I also blew shop air through the hole, again with little resistance yet the oiling issue continues. Would this indicate a spun bearing or a clogged groove? I don't know if the cam is grooved or cross drilled. Does anyone make a cross drilled cam for Y-blocks anymore since it appears cross drilled is the better idea?

I have a rebuilt set of G heads I'll be installing soon and while the heads are off I'm going to run the oil pump with a drill to see what comes out of the feed holes in the block. Right now the driver's side oils just fine but he passenger side is nearly dry in comparison.

years ago almost everyone said the grooved cam was the way to go.but i used to think i never saw an overhead oiling kit on a 55.i suppose there was a few but dam few.ford took a step backwards as far as i can see.

I used the super fine sandpaper trick on mine many years back. Worked fine. Still working with the second cam.

Dobie.  To date, the only spun cam bearing I’ve ever seen in a Y was one of my brass ones where I did not have enough oil clearance built into it.  That engine was in my race car and learned quite quickly that brass likes additional oil clearance versus what is used for a babbitt constructed bearing.
 
If your engine has been previously rebuilt and the cam bearings were replaced, then there’s always the chance that grooved camshaft bearings were installed and those do not work well with cross-drilled camshafts.
 
The Engine Tech CC-508 cam bearings do fit all years of Y using the grooved center journal camshaft.  They do not work with cross drilled camshafts without modifying them.  Durabond offers two different cam bearing sets with one being for grooved journals and the other for cross-drilled journals.
 
I’ve come across a number of Ford Y’s that had been rebuilt at least once in their lifetime that had evidence of having overhead oilers before I purchased them as core engines.  In tearing these engines down, some had the center cam bearing installed incorrectly by the rebuilder where only two of the holes aligned and the third did not.  From the git go, these engines failed to provide oil to one bank or the other.  All three holes must be aligned.  Overhead oilers were obviously a cheaper fix than tearing the engine back down.  Other engines simply had the softer cam bearings and the center journal groove was simply pushed into the bearing material thus shutting off the oil flow to the top.
 
For whatever reason, when there is an oiling issue at the rockers, it’s the right bank that experiences a reduction in oil flow first.  Sludge was the largest single issue with top end oiling back in the day.  At a shop I worked at during the early seventies, one of the mechanics had fabbed up a flat piece of steel with a zerk fitting that would bolt up to the head with the rockers off.  By using a grease gun and and pumping white lithium grease into that oil hole, any debris or sludge was pushed back into the engine thus clearing up the feed for the oil.  That approached worked well as the grease had a low melting point and easily dissolved when the engine warmed up.

Lorena, Texas (South of Waco)

Thanks, Ted. I'll have a better idea what's going on when I get the G heads back from the machinist. With the heads off I'll run the oil pump with a drill to see how much oil comes out of the feed holes. If it's pretty much equal on both banks I'll assume there's a blockage in the head or rocker shaft although when I had the rocker assembly off I ran some solvent through the shaft as best I could without taking it completely apart. Nothing of note came out of it. I have a set of rebuilt rocker assemblies that will go on the G heads anyway. If oil flow is still restricted the engine is going to the machine shop for a refresh.