Cam bearing oil hole location.

[slowcamaro]

In a journal with an annular groove does the direction of the cam bearing oil hole matter? I've heard differing opinions.

Inline with the hole from the mains. (6 o'clock)
2 o'clock position
12 o'clock position

Now Ive read varying information. One source was Mahle the other was Federal Mogul. I forget which was which and One said as long as their was an annular groove going the entire way around the hole location didn't matter. The other suggested 2 o'clock was the most effecient.

Does anyone have any solid evidence of it making a diffeence?

[David Pozzi]

I did a lot of asking about this several years ago. My engine guy installed them with holes at 6 O'clock, didn't seem right to me to have them where the cam pressure was highest and clearance the lowest due to cam pressure.
My bow tie block came with them all at the 4 O'clock position.

I talked to several bearing reps at SEMA and they all had no clue! Found a research facility in Texas I think it was, sent an email to them and while they were doing bearing clearance research on running engines. They didn't have a lot to say on it either, but agreed injecting oil just prior to the heaviest loaded area seemed logical. I'd guess that puts the hole somewhere before the 4 O'clock area, 2 to 4 seems to make sense to me, 12 O'clock was thought to just waste oil flow out the sides.
David

[Neil B]

I did a lot of asking about this several years ago. My engine guy installed them with holes at 6 O'clock, didn't seem right to me to have them where the cam pressure was highest and clearance the lowest due to cam pressure.
My bow tie block came with them all at the 4 O'clock position.
David

On my Bow-Tie block, I had the cam bearing installed with the oil hole directly over the oil hole with the split in the ACL bearing at 12 o'clock. If I stick a cleaning brush down the oil hole in the mains, I can see bristles through the cam bearing. I don't recall the cam journals having a groove (but it's been awhile since the bearings were installed and I may be mistaken).