cam bearing oil hole alignment

[coronetcustom]

machine shop returned my block with new cam bearings installed in a way that side of the bearing hole overlaps 1/3rd or 1/4th of the oil hole on block(all).they assure me that this is no problem for lubrication. can anyone tell me if this is correct? don't know why they didn't put them straight in first place..
engine specs.1971, 383mopar, engine has hydraulic mopar purple cam. car is everyday driver, no racing, occational rubber burning for fun.

[ehostler]

I would tell them to reinstall with the correct orientation. I would accept no compromise on proper oiling.

[peg leg]

But I would insist on new bearings. Removing them can put burrs on the edges. That's likely why they said it would not affect oiling. Yikes!

[coronetcustom]

i believed them and i already assembled the engine. it´s still on stand though because them bearings been bothering me.. i guess i got to take it apart. i took plenty pictures of the block when it came back. don´t know how to post them here.. almost all bearing surface have minor scratches and burrs. i bought the bearings, they looked quite different in box. this is my first engine re-built and i don't have much experience on these engines. had a harley for a long time, i know shovel engine back and forth..but that doesn't help me much here. my guide in rebuilding this engine has been "Don Taylor's-How To Rebuild Big-Block Mopars" from HPbooks, i have found the book excellent.

[Mecki]

The cam bearings I have installed (Clevite 77) did not exactly match the holes in the block. The passages in the block were bigger than the holes in the bearings, so if the hole is completely over the passage, then it's OK. #4 has the oil passages to the rocker shafts also, so there is three holes to match. I remember that I had to compromise a little to get it good, but it was not a perfect match.

[coronetcustom]

bearing-oil.passage.jpg
picture here.

[coronetcustom]

oil holes are not completely blocked, but partly, on every bearing. more than half of each hole is open

[Mecki]

Do you remember how #4 rocker shaft oil passages aligned up?

If you're not sure, and the bearings really don't look so good... I think I would replace them, but that's just me.

[ehostler]

That is definitely a restriction. They just slapped it together. They don't want to fix it,a s the bearings will have to be replaced.

[dwc43]

Originally Posted by coronetcustom

Attachment 11391
picture here.

Those bearings look like crap to start with, and that's a major restriction. Remember the oil that feeds the rockers comes from two if those cam bearings and with that restriction you have there, it will restrict oil to the rockers. Good way to fry some push rods on the rocker end. Get it fixed, either now or later. Later always cost more though.

[coronetcustom]

Ok, latest news:
machine shop says they´re(bearings) are good and work solid. 90% from other comments including this forum, other machine shops and parts suppliers are in favor for replacing them. i had a brief meeting with the shop, showed them printed copies of all comments and and they are not willing to fix the problem. i´ll take the engine to a different shop and balance the books later. thanks for the advice to all.

[dwc43]

Do some research on the shops in your area. Make sure they know Mopars, cause most of them around here don't and don't care.

[John Kunkel]

Compare the size of the hole in the cam journal (typically .150") that actually distributes oil with the hole in the cam bearing (typically .250") and you'll see that the misalignment can be well over 30% without restricting oil flow.

Also the process of scraping the cam bearings will leave a finish similar to that in the photo; doesn't effect the bearing enough to mention.

[TrashedCharger]

That's right. Most aftermarket bearings have a slightly larger oiling orifice to compensate for marginal error upon installation. As long as you see a true hole through the bearing in the block, you are okay. If the actual hole in the block is being covered, that would definitely create a problem.

I would at least pull the intake, timing cover, gears/chain and cam out to inspect those opennings once more before deciding on what to do.

[23T-Wedge]

Before you do anything drastic, get a primer shaft, pull your valve covers, and prime the oil system. If you are getting oil "to the rockers" with a drill motor, you shouldn't have any problem with the engine running.

[coronetcustom]

i'll let you know how things proceed. thanks again for all advices. much appreciated.

[party340]

Same thing happend to me on my 340. The bearing was so out of wack that it was rubbing on the lifter. I opened the oil hole with my dremel and grinded the part of the bearing that was rubbing on the lifter. That was in 2000 and with 20, 000 + miles no problems.

[ehostler]

DW, he is in Finland. I doubt that they have any shops that specialize in MOPAR.

Trashed, take a look at his picture. The hole is partially covered by the bearing.

23T, it will flow oil the way it is; however it is a restriction and it will be decreased volume.

[23T-Wedge]

If it is decreased volume it will be pretty obvious, in which case he can then tear back into it. Otherwise if volume is sufficient, he will have saved himself a lot of trouble.

[Mecki]

Originally Posted by coronetcustom

Ok, latest news:
machine shop says they´re(bearings) are good and work solid. 90% from other comments including this forum, other machine shops and parts suppliers are in favor for replacing them. i had a brief meeting with the shop, showed them printed copies of all comments and and they are not willing to fix the problem. i´ll take the engine to a different shop and balance the books later. thanks for the advice to all.

The bearings would probably work (well over the warranty time) even with restricted oil passages and scored as they are now. The thing is that a professional machine shop should be able to install those bearings aligned and without scoring the soft bearing metal, that's the reason you have a professional to do the job in the first place. It does not have to be a Mopar shop to do that. However, Mopars are pretty well known here in Finland, many machinists are car enthusiasts too, so if you are lucky you find one who knows the particular engine.

That picture does not show a professional job and they should admit that. Getting them to compensate for replacing the bearings is not so easy, but you could tell us the name of the shop, so that we could avoid using them for anything in the future. Some shops takes their reputation seriously, and they should. This is a small country and a bad name is soon known everywhere.

IMO the most critical thing about these bearings is the #4. If the main passage to bearing alignment is similar to the one in the picture, I'm pretty sure that at least one of the rocker shaft passages is almost blocked, maybe even completely. Just priming the engine would only reveal if the passage is completely closed. As I said earlier, this bearing must be aligned with three passages and it's not a 100% match. I would not start the engine without checking that first. If it turns out that one passage is blocked, then the shop is out of excuses, and the money thing should be pretty clear then.

[451Mopar]

Were those bearing actually replaced? The bearing surface shown in the photo looks pretty scuffed up. Could you see any marks in the cam bore of the block where the bearings were driven in?
The alignment is not great, but will probbably be OK if you can get oil up to the rocker arms. From your photo, I would be more concerned about the bearing surface than the alignment. Have any other pictures?

[John Kunkel]

Originally Posted by ehostler

23T, it will flow oil the way it is; however it is a restriction and it will be decreased volume.

Yea, but how much volume is needed? Considering the cam journal's running clearance and the fact that the cam only runs at half crankshaft speed, the partially misaligned hole will still pass plenty enough oil; even on the #4 journal.

Anybody here ever scraped cam bearings to get the cam to fit? It doesn't leave a "right out of the box" surface finish but still provides a bearing surface.

[coronetcustom]

ok, i took cam out and checked with mirror tool the upper oil passages on #4, they´re open about the same as others, no less.(when i got the block back from first shop, i checked all oil passages with coat hanger wire so i knew they were open, but i didn´t have picture of #4 upper holes). i sent all new pictures to proper machine shop. they agree it´s not good fit, or professional looking job, but they also said oil flow would be sufficient. they adviced me to lightly rub bearing surface with kind of "cleaning sponge thingy" to get smooth surface. i'm thinking of assembling the engine as it is now.. i´m not too happy about taking first compromise with this project because it´s complete engine rebuild.