Camshaft groove - bearing supply hole


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By paul2748 - 16 Years Ago
Is there any specs on the groove for the grooved camshaft - depth and width? What is recommended? Another related matter - the holes in the center bearing that supplies oil to the rockers - should they be as big as the holes in the block? A friend told me that one of the oil passage holes in the cam bearing (the one toward the the crank?) overlapped the hole in the the block leaving the oil passage about 1/3 the intended opening size. The other holes in the bearing aligned ok Should the smaller hole be made bigger to the size of the block? Thanks
By Doug T - 16 Years Ago
Strictly from memory the '57 and up groove in the cam journal is u or v shaped and about .060 wide and deep. The 56 and earlier had a drilled hole through the center journal. The change from drilled to grooved happened at the '57 model year and seems to have been an improvement in oiling the rockers.  I once had a groove cut in a drilled cam and it seemed to work OK.  I now remember to order the cam for '57 and up to be sure to get the grooved design no matter what year the engine itself.

The oil is supplied to the cam bearing from the hole at the bottom of the cam bearing shell so I would say that it is very important that this hole be aligned correctly.  I have never held these bearing shells in my hands but I think in a set, all 5 shells are drilled for the 3 holes and have no groove.  They are the very first thing normally installed during a rebuilding (my machinist always does it for me) and proper installation is crucial to oiling the top of the engine, this is something a non experienced machine shop could easily get wrong.  Discuss it with your machine shop before they start because there is no replacable part buried deeper in the engine!

The center cam bearing on a Y block deviates a lot from the classic hydrodynamic design of journal bearings and still seems to work, but I wouldn't call it one of the engine's strong points.

By DANIEL TINDER - 16 Years Ago
Paul,



John Mummert specifies .030"-.050" minimum groove depth. Do not widen (increases bearing wear) or cut "V" shaped (reduces flow as journal wears).
By Ted - 16 Years Ago

Part of the problem with the grooved camshaft journal is that a ‘soft’ cam bearing will deform or wear into the groove just enough to stop the oil flow altogether.  It is a common practice to make the groove deeper in the camshaft center journal though with 0.060” total depth being expected to be adequate.  Not all cams as supplied will be this deep.  I’ve also talked to machinists that use to drop a long drill bit in the topend oiling hole in the block and punch a pair of larger holes in the cam bearing and then dress the bearing to assist in topend oiling.

 

An alternative for the top end oiling is to machine a groove in the blocks center cam journal hole that connects all three oiling holes together.  The center camshaft bearing is then installed in the block over this machined or cut groove.  With this block groove in place, no cam bearing or cam journal modifications are required and a full flow of oil is able to get to the rockers regardless of the camshaft or bearing design.  Any excess in oil that’s going to the topend can be reduced with the use of a restrictor placed either in the head under the rocker pedestal or putting the restrictor in the bottom of the pedestal.
By 46yblock - 13 Years Ago
Ted (2/11/2008)

Part of the problem with the grooved camshaft journal is that a ‘soft’ cam bearing will deform or wear into the groove just enough to stop the oil flow altogether.  It is a common practice to make the groove deeper in the camshaft center journal though with 0.060” total depth being expected to be adequate.  Not all cams as supplied will be this deep.  I’ve also talked to machinists that use to drop a long drill bit in the topend oiling hole in the block and punch a pair of larger holes in the cam bearing and then dress the bearing to assist in topend oiling.

 

An alternative for the top end oiling is to machine a groove in the blocks center cam journal hole that connects all three oiling holes together.  The center camshaft bearing is then installed in the block over this machined or cut groove.  With this block groove in place, no cam bearing or cam journal modifications are required and a full flow of oil is able to get to the rockers regardless of the camshaft or bearing design.  Any excess in oil that’s going to the topend can be reduced with the use of a restrictor placed either in the head under the rocker pedestal or putting the restrictor in the bottom of the pedestal.

Sorry about bringing up this old thread, but I've been searching to find the depth/width of the groove in the block behind cam bearing?  What should it be?

By marvh - 13 Years Ago
I have always cut the groove .032" deep (and kept stock width) in the camshaft journal since the early 60's when pulling wrenches for the LMM (Lincoln,Mercury Meteor dealer). That is depth on one side not diameter difference on the journal.

If I had the tools to do the groove behind the camshaft bushings I would do it that way today as the logic is better.



The last two 312's I just built in the last year I used the Clevite 77 SH-559S bushings. Just my personal preference is Clevite.



I had to place restrictors in both these engines to reduce the amount of top oil going to the rockers. I drilled a 5/16" allen screw and blind threaded the rocker stand so the allen screw would bottom out before hitting the rocker shaft. These were the only engines I ever had that problem with.



When reading the little note inside the bushing package I found that Clevite has changed the design of this camshaft bushing to allow more oiling to the top. The note reads The SH-559 bearings in this set are the latest design and supersede all previous parts. The elongated oil metering holes assure equal oil supply to the upper valve train under all operating conditions. They must be installed with the longest slot positioned toward the right bank and the middle slot positioned toward the pan



With this change in the bushing design over-oiling the top end and flooding the oil return galleries could be a problem. Restriction now maybe a necessity if that happens.



marv
By 314 - 13 Years Ago
any stock cam i measured was .015 to .017 deep or total .030 to .034.so you need to go twice that mutch.one side of the cam bearing slot only goes about 1/16 or a little more into the rocker passage hole.this was done to force more oil up the other side which never got enough.so its important to install them right.
By 46yblock - 13 Years Ago
So is it .032 deep on the groove in block, and same width as cam groove?
By simplyconnected - 13 Years Ago
Good question Paul, because camshaft groove depth is really a simple but important link in oiling the whole rocker arm system.

I used the new Clevite 'slotted' cam bearings in my 292.  Only one bearing was slotted in my set so it looked different from the other four; clearly intended for the center journal.  After correctly installing, I used a very high tech method for flow; I blew down both deck holes and found one side was more restricted than the other.

Ted mentioned using a long drill.  That's exactly what I did.  My drill was precisely 1/4"  in diameter and I used a cordless drill.  Then, I de-burred the inside bearing surface.  In reality the drill bit may be smaller.  I sharpened the tip to a 'domed' shape so it wouldn't catch on the slots so bad as it cut (but that doesn't matter, either). 

My '59 OEM cam had a slotted center bearing with no holes.  I don't have a lathe, but I really didn't need one.  This slot is just a conduit for oil flow (but it should never be the bottle neck).  I simply put my cam in the center slot of my Workmate horse, used my angle grinder with a thin blade, and carefully ground as I rotated the cam by hand.  Slowly, the groove deepened to my satisfaction.  Was it sixty thousandths?  It really doesn't matter if it's more.  In fact, it doesn't matter if the slot is eccentric as long as the minimum deepth is enough.

Two schools play a big role in the next part.  To pressurize or not to pressurize; I pressurized both my rocker shafts.  Each of the two holes on all 16 rocker arms have great oil flow, and my oil pressure went UP when I pressurized my shafts.  Don't forget to 'center' your rocker arms, or slot the oil holes on the bottom of the shafts.

Resistance to flow creates pressure.  My increased pressure and good visible rocker arm flow proved that I needed no more restriction at the stands.

Flow takes the path of least resistance but more resistance raises pressure, which ensures all my rocker arm holes will be clear for many years down the road.  - Dave

Good question Paul, because camshaft groove depth is really a simple but important link in oiling the whole rocker arm system.

I used the new Clevite 'slotted' cam bearings in my 292.  Only one bearing was slotted in my set so it looked different from the other four; clearly intended for the center journal.  After correctly installing, I used a very high tech method for flow; I blew down both deck holes and found one side was more restricted than the other.

Ted mentioned using a long drill.  That's exactly what I did.  My drill was precisely 1/4"  in diameter and I used a cordless drill.  Then, I de-burred the inside bearing surface.  In reality the drill bit may be smaller.  I sharpened the tip to a 'domed' shape so it wouldn't catch on the slots so bad as it cut (but that doesn't matter, either). 

My '59 OEM cam had a slotted center bearing with no holes.  I don't have a lathe, but I really didn't need one.  This slot is just a conduit for oil flow (but it should never be the bottle neck).  I simply put my cam in the center slot of my Workmate horse, used my angle grinder with a thin blade, and carefully ground as I rotated the cam by hand.  Slowly, the groove deepened to my satisfaction.  Was it sixty thousandths?  It really doesn't matter if it's more.  In fact, it doesn't matter if the slot is eccentric as long as the minimum deepth is enough.

Two schools play a big role in the next part.  To pressurize or not to pressurize; I pressurized both my rocker shafts.  Each of the two holes on all 16 rocker arms have great oil flow, and my oil pressure went UP when I pressurized my shafts.  Don't forget to 'center' your rocker arms, or slot the oil holes on the bottom of the shafts.

Resistance to flow creates pressure.  My increased pressure and good visible rocker arm flow proved that I needed no more restriction at the stands.

Flow takes the path of least resistance but more resistance raises pressure, which ensures all my rocker arm holes will be clear for many years down the road.

Hope this helps  - Dave

By rick55 - 13 Years Ago
Hi Dave

Nice to see you back on the site.

I always appreciate your input.

Regards
By simplyconnected - 13 Years Ago
Thanks for the kind words, Rick.  I hang my hat over at Squarebirds.org now, as their Webmaster.

Bill Knighton brings us news of the Oceanside Thunderbirds in Perth and other hot rodding events.  I am very impressed with the Australian's enthusiasm for fine Fords and hot rods.  I'm also jealous of your car.  I hope my '55 will look as good as  your car after I get it painted.  I love your colors, and will use them; Colonial white on top and blue on the body (mine's a Fordor Customline, not a prestigeous Fairlane).

Cheers  - Dave 

By marvh - 13 Years Ago
46yblock (3/25/2011)
So is it .032 deep on the groove in block, and same width as cam groove?




I have not done the groove behind the camshaft bushing modification so I don't know what depth it should be. I don't want to give incorrect info if I don't know.



Perhaps Ted can jump in here he has done that mod and would be the most knowledgeable as to depth of the groove behind the bushing. There was a picture in one of the previous posts as to the tool he used. I cannot find it at the moment. I would like to know the depth of the groove behind the bushing also as I feel that is the best of the two modifications due to the camshaft bushings wearing in and could choke down the oil flow to the top end over time especially if your are running higher valve spring rates.



Playing devils advocate now these engines are not normally our daily drivers anymore. Would it wear into the bushing if we only put under 10K miles a year and running stock valve springs?

I have seen many high milers with the groove deepened in the camshaft still oiling the top well.



The after market cams I have measured were between .014" -.017" deep also.. There were some aftermarket camshafts about ten years ago that were about .013" deep. These camshafts were bad news for top oiling. The original Ford camshafts I have measured were about 021" deep.



How we arrived to use the figure of .032" for depth was we had a fleet of school buses with 292's in the early 60's that had bad top oiling problems. The original camshafts were .021" deep and not oiling sufficient, the group of us mechanics felt 50% deeper would be a good starting point. It proved to work well.
By YellowWing - 13 Years Ago
Here is the post that describes how to do the modification.

 http://www.y-blocksforever.com/forums/Topic36955-3-1.aspx?Highlight=cam+groove+modification

By Ted - 13 Years Ago

Mike.  Thanks for finding that posting and putting up the link for it.

 

Marv.  The problem with many of the new replacement Y-Block Ford cam bearings is that they are now constructed using a much softer babitt material than the originals.  As a result, bearings made from this softer material have a propensity for advanced bearing wear or deformation into the camshaft groove and especially where the valve spring pressure has been increased.  This same issue shows up with the Ford 427 sideoiler engines where the #2 & #4 cam journals use a similar groove for top-end oiling.

 

Regarding the depth of the groove in the center camshaft journal itself, here’s the spec posted by Dennis K. awhile back.

Dennis K. 4/22/2008
The #3 journal oil groove specification is .095-.085 wide at the surface, .022-.016 deep at the center, and the reference radius is .066 R. 

 

And here’s the link to that particular thread.

http://www.y-blocksforever.com/forums/Topic11666-3-2.aspx

 

Based on the original Ford specification for the camshaft groove, a groove machined into the block behind the center cam bearing should be at least this deep and even deeper would be desirable.  My own preference is to go at least 1/16” wide by 1/16” deep.  Any excess in oil flow to the top can be regulated with drilled set screws that are threaded into the bottom of those rocker stands where the oil comes out of the heads.  A favorite orifice size in these set screws for top end restriction would be 0.078” (5/64” drill).  If the hole size is 0.125”, there’s a good chance that oil flow to the top end can be excessive and especially if the rocker shaft oil tubes are still being used.

By marvh - 13 Years Ago
Ted (3/27/2011)

Mike. Thanks for finding that posting and putting up the link for it.

Marv. The problem with many of the new replacement Y-Block Ford cam bearings is that they are now constructed using a much softer babitt material than the originals. As a result, bearings made from this softer material have a propensity for advanced bearing wear or deformation into the camshaft groove and especially where the valve spring pressure has been increased. This same issue shows up with the Ford 427 sideoiler engines where the #2 & #4 cam journals use a similar groove for top-end oiling.


Thanks Ted for the reply regarding the change in the bearing material composition. I was not aware that the new bushings are mfg with a softer material this will definitely lead to a faster wear than the old stock. Thank you.

One point I was trying to bring out is the change to the bushing design where the mfg has attempted to fix the poor oiling problems. With this change now we likely will have excess oiling to the top end unless we add a restriction to control the flow. This is something for the re-builder to watch for.

marv