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Cam bearing oil hole misalignment

Posted: Sun Mar 03, 2024 10:42 pm
by 850RS
I searched to see if this has come up before but I was unable to find a previous topic.

I’m test fitting an old cam bearing in a new to me block and the oil galley from the main is lined up perfectly. Unfortunately, it blocks half of the oil galley to the valve train. What is the best way to fix this? I was thinking of filing a small bit of the cam bearing out to give the valve train a little more oil.

Cheers

Re: Cam bearing oil hole misalignment

Posted: Sun Mar 03, 2024 11:36 pm
by Peter Laidler
Ah....... this was discussed at some length a couple of years ago and related to pressures - over - volumes as I recall. And the answer was leave it alone as it is this seemingly 'misalignment' that allows the oil feed to....... anyway..... . Correct me if I'm wrong....

Re: Cam bearing oil hole misalignment

Posted: Mon Mar 04, 2024 2:22 am
by Spider
How's the alignment of the other hole ?

If that one (which feeds oil IN) is OK, then leave it.

If the other one is out, then best way to to remove the bearing and re-fit it on the correct alignment.

Re: Cam bearing oil hole misalignment

Posted: Mon Mar 04, 2024 1:36 pm
by CooperTune
Am I confused? I thought the rocker arm feed hole going up was the small round hole. Does installing wrong provide full time full pressure oil, flooding valve cover? Steve (CTR)

PS, I have always considered half a hole to be a hole.

Re: Cam bearing oil hole misalignment

Posted: Mon Mar 04, 2024 4:51 pm
by gsamps
Yep, bearing shell in picture is reversed. Small hole to rocker feedd.

Re: Cam bearing oil hole misalignment

Posted: Mon Mar 04, 2024 5:22 pm
by Ronnie

Re: Cam bearing oil hole misalignment

Posted: Mon Mar 04, 2024 6:56 pm
by 850RS
Thanks everyone for your input.

The orientation makes more sense now that it’s been explained. Just goes to show that putting things back the way you found it isn’t always the best plan! Appreciate all of the wisdom here on the forum.

Cheers

Re: Cam bearing oil hole misalignment

Posted: Mon Mar 04, 2024 7:45 pm
by CooperTune
So, D/S would have been a 970 or 850 in the early days? If you are building an 850 I hope you line bore for all cam bearings. Steve (CTR)

Re: Cam bearing oil hole misalignment

Posted: Mon Mar 04, 2024 8:45 pm
by 850RS
CooperTune wrote: Mon Mar 04, 2024 7:45 pm So, D/S would have been a 970 or 850 in the early days? If you are building an 850 I hope you line bore for all cam bearings. Steve (CTR)
They run up to 1100 for DS now. I’m a 998 at +.040 so 1027 cc.