[GoreMaker]

I ordered a set of new cam bearings. I didn't bother looking at the picture before ordering. I did not remove the old cam bearings, the machine shop did, and they did the shake-n-bake, and get didn't return the removed bearings, so I have nothing on hand to compare to. These are the bearings I ordered:

https://www.summitracing.com/parts/dur-pp-4t

They don't match the holes in the block at all. The cam bearing bores have 1 oil hole in the bottom of bearings 1, 3 and 5, and a hole in the top AND bottom of bearings 2 and 4. These bearings each have 3 holes in a delta. I got the part number from the Butler website, but the picture they have shows only one hole in all 5 bearings. I'm kinda confused

[lust4speed]

That is a correct part for a Pontiac V8. Now some will disagree with me but I personally don't like coated bearings because most of the time a little shaving of the Babbitt has to take place to have the cam turn easily. Not much use in having coated bearings if you are shaving some of the coating off. I just go for the PP4 bearings (with the P4 not really being that bad of choice either).

The reason #2 and #4 bearing journals have top holes is that particular block had the threaded holes for the valley pan bolts extend all the way through to the journal. Not all blocks are drilled (or threaded) completely through. The triangular positioning of the bearing holes is correct and present for all bearings and only receive oiling through the bottom hole.

[25stevem]

I am failing to see where the precived problem is here.

The Cam bearings only need to have out of how many of the holes that may be in them lined up with the oil feed hole the main web, that's it , job done!

[Half-Inch Stud]

Yea, the Cam Bearings with multiple holes is a brief curiosity just before you go pressing them in.

[mgarblik]

If the block was run through the "Shake and Bake" process, I assume that means thermal cleaned. Hopefully, when they were done, they ran a ball hone through the cam bores just a pass or two. The blasting part of the thermal cleaning process will close the holes just slightly and lightly abrade all surfaces. Every threaded bolt hole needs to be chased, the mains will need a line hone and the deck will need a light re-surface to restore them. It's just part of the normal process. Great way to clean though. Good luck with it. Generally pounding new bearings into thermal cleaned blocks not prepped, results in tight cam bearings. Cam should turn with 2 fingers with all bearings installed and light oil. Good luck with the build.

[Bill Hanlon]

The 3 hole cam bearings were very necessary for the early, stud-oiling for the rocker arm balls. which were used from to 1955 until 1964 on some engines. Combined with holes in the 2nd and fourth cam journals small amounts of oil would be metered up a passageway in the block, through the head gasket and into a gallery in the head. The bottom end of the rocker studs sat in this gallery and passed oil up the hollow stud and out to the rocker ball.

Jack Griffin had a good posting explaining the math behind this, but I cannot find it.

[25stevem]

I don’t have a 64 or earlier block here to look at, but I don’t think it was the cam bearings in those two locations that fed the heads because the bearing would have to be grooved, if not then the cam bearing bore in those two locations would need to be grooved, or the cam itself would need to be grooved.

If I am recalling right there was a oil crossover hole in the main web that fed those two passages up to the heads.

Anyone get a empty early block to roll over and peer into?

[Murf]

Originally Posted by 25stevem

I don’t have a 64 or earlier block here to look at, but I don’t think it was the cam bearings in those two locations that fed the heads because the bearing would have to be grooved, if not then the cam bearing bore in those two locations would need to be grooved, or the cam itself would need to be grooved.

If I am recalling right there was a oil crossover hole in the main web that fed those two passages up to the heads.

Anyone get a empty early block to roll over and peer into?

Can’t get a good pic of the 59 block I’m looking at but it has.

1 hole on bottom by slot on the front of block

1 at bottom & 10 o’clock on second

1at bottom on 3rd bearing

1at bottom & 2 o’clock on 4th

1 at bottom on back.

[GoreMaker]

That would certainly explain why 3-hole bearings can accommodate such a wide range of blocks.

[racegto65]

Originally Posted by mgarblik

If the block was run through the "Shake and Bake" process, I assume that means thermal cleaned. Hopefully, when they were done, they ran a ball hone through the cam bores just a pass or two. The blasting part of the thermal cleaning process will close the holes just slightly and lightly abrade all surfaces. Every threaded bolt hole needs to be chased, the mains will need a line hone and the deck will need a light re-surface to restore them. It's just part of the normal process. Great way to clean though. Good luck with it. Generally pounding new bearings into thermal cleaned blocks not prepped, results in tight cam bearings. Cam should turn with 2 fingers with all bearings installed and light oil. Good luck with the build.

Also hopefully they ran a ball hone through the lifter bores as well as they also get tight after thermal cleaning

[Bill Hanlon]

Short between my keyboard and chair. Jack Gifford, not Griffin.

Here is the thread that Jack contributed to.

https://forums.maxperformanceinc.com...d.php?t=783279

[25stevem]

Thanks for that link!
Now I see the need for those extra holes in the cam bearings on early rocker stud oiled motors.
I have never seen nor built any motor earlier than a 65.