Cam bearing orientation

[bobbiemartin]

I have been corresponding with several 6.5 gurus and I'm still not 100% sure on the cam bearing oil hole orientation.

On the front bearing, the factory manual says the oil holes need to be at 1:00 and 4:30, although the Military manual says 12 and 4 - so I would say they are reasonably close.

They both say there should be a notch in #1 cam bearing facing out, but my replacement Mahle bearings do not have a notch and I'm told most aftermarket bearings do not have the notch.

On the remaining cam bearings, there is only one hole. The military manual says to install the oil hole at 4:00 (it actually says to install at 10:00 with the block inverted, which is 4:00 when upright)

Some of the factory manuals say oil holes at 1:00. Others say to align with oil feed holes. There is an oil feed hole at 6:00, but I do not think this is the correct orientation.

Any input or other documentation would be appreciated. Also, if you have replaced the cam bearings, did they have a notch in the #1 bearing?

 

[chevyCowboy]

mine do not. i had the mechinest install them not sure how he put them in but i was under the impression that there was a grove going all the way around so the oil will got threw the hole in bearing no matter where its at

 

[bobbiemartin]

i was under the impression that there was a grove going all the way around so the oil will got threw the hole in bearing no matter where its at

Yes that is true, but from what I understand, the oil needs to enter in a certain spot during the cam's rotation to provide the proper oil film on the bearing. Too early or too late and the cam may not have enough oil on the bearing. Something about how much tension between the cam and bearing, as it is opening the valves. There is an optimum location for the oil to enter, and that is why the oil holes need to oriented properly - at least that is how I understand it.

 

[540s10]

if it has the groove all the way around the bearing follow the military spec.

 

[chevyCowboy]

damn now im wondering if i should change the way mine are

 

[540s10]

i wouldn't worry about it, there is no adverse effect on a small block chevy, and they have more pressure on the cam than our trucks do.

 

[bobbiemartin]

I talked to Peninsular today. They said front bearing oil holes at 1:00 and 4:30 with notch facing outside, and the rest at 1:00. I should have a new set of bearings tomorrow and they are supposed to have a notch in #1. I'm going to have mine redone as above.

 

[bison]

the oil hole location before pulling out the old brg should give you enough indication how to press the new one in,being off a wee bit aint gonna kill it.

 

[bobbiemartin]

I got the new bearings today. Mahle Clevite 77 bearings, made in the USA! Although the parts guy swears they are Durabond bearings marked Clevite. None the less, they are going in. They do have a notch on the front bearing as well. However, they are seamed bearings and in order to get the seam near 11:00, the oil hole has to be at 4:00. If they are at 1:00, the seam won't be anywhere near the top, so I'm going with the military manual and putting the holes at 4:00, seams at 11:00.