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Cam bearing install issue

Posted By: Chassisman

Cam bearing install issue - 02/15/12 06:26 AM

The old man is putting his 512 together....he installed the cam bearings....cam wont fit....both the new and old cam wont go in easily. I thought maybe a bad set of bearings....so we knocked them out......used a different tool and a new set of bearings....I even had him 800 oil sand the bores to make sure they were clean......guess what....same issue...this time we're checking figment as we go. So far its #4 the 3 hole bearing with an issue.
You guys ever ran into this?.....I've NEVER had this happen in 30 years of building motors.
Posted By: Al_Alguire

Re: Cam bearing install issue - 02/15/12 06:37 AM

Not all that uncommon. I use an old cam core to make a cam bearing "cutter". Just cut pie grooves into the bearing journals and install the cam and spin it a bit. It will true up the bearings. UNLESS you have a bent cam you are trying to install.
Posted By: Chassisman

Re: Cam bearing install issue - 02/15/12 06:50 AM

Quote:

Not all that uncommon. I use an old cam core to make a cam bearing "cutter". Just cut pie grooves into the bearing journals and install the cam and spin it a bit. It will true up the bearings. UNLESS you have a bent cam you are trying to install.

Al.....we'll give that a shot....we tried the new cam and the old one....both bad the same issue.....thanks
Posted By: Biginchmopar

Re: Cam bearing install issue - 02/15/12 07:12 AM

Al is on it.

We had to do the same with the my current motor. I wipped out a cam bearing on the dyno. The shop I took it to used a trued cam core with pie cut and cleaned the bearing were it was tight.

Posted By: 383man

Re: Cam bearing install issue - 02/15/12 09:29 AM

I actually had that same problem when I put my 493 together last winter. I also did what Al said but it did not fix it as mine was tight enough that I had to force it in which was a no no. I ended up taking all the bearings back out except the #1 and 5. Cam went right in so I put the bearings back in one at a time intil I found when I put #3 in the cam would not go all the way in. After I saw scratches on the back of the #3 cam bearing I saw where a piece of casting right next to the #3 bearing hole had laid over into the cam bearing hole and it was going in the front part of the bearing hole so that it stayed there when I drove the bearing in and it was raising the bearing shell just enough to cause the problem. I used a file and filed it off and ran a hone thru the cam bearing hole. Installed another bearing and all was fixed ! Ron
Posted By: jamesc

Re: Cam bearing install issue - 02/15/12 03:25 PM

Quote:

I've NEVER had this happen in 30 years of building motors.



i've never had one (bb mopar) that didn't require some attention here. always do the cam bearing one at a time so you can find the offending one(s). you can use a cam core or bearing scraper AKA razor blade to dress the tight spots
Posted By: HPMike

Re: Cam bearing install issue - 02/15/12 03:48 PM

Quote:

Quote:

I've NEVER had this happen in 30 years of building motors.



i've never had one (bb mopar) that didn't require some attention here. always do the cam bearing one at a time so you can find the offending one(s). you can use a cam core or bearing scraper AKA razor blade to dress the tight spots



Exactly...

It was my understanding that the bores on production blocks were all over the place and the factory actually had a fixture that final honed the bearings true. I build a lot of Chrysler big blocks and its very rare that I dont have some issues with cam fitment. Not a big deal to get it straightened out, but it always needs attention.

MB
Posted By: Cab_Burge

Re: Cam bearing install issue - 02/15/12 08:39 PM

Quote:

Quote:

Quote:

I've NEVER had this happen in 30 years of building motors.



i've never had one (bb mopar) that didn't require some attention here. always do the cam bearing one at a time so you can find the offending one(s). you can use a cam core or bearing scraper AKA razor blade to dress the tight spots



Exactly...

It was my understanding that the bores on production blocks were all over the place and the factory actually had a fixture that final honed the bearings true. I build a lot of Chrysler big blocks and its very rare that I dont have some issues with cam fitment. Not a big deal to get it straightened out, but it always needs attention.

MB

One out of four blocks will need work on the cam bearings, install them one at a time and then slide the cam in, fix as needed
Posted By: Chassisman

Re: Cam bearing install issue - 02/15/12 08:53 PM

Quote:

Quote:

Quote:

Quote:

I've NEVER had this happen in 30 years of building motors.



i've never had one (bb mopar) that didn't require some attention here. always do the cam bearing one at a time so you can find the offending one(s). you can use a cam core or bearing scraper AKA razor blade to dress the tight spots



Exactly...

It was my understanding that the bores on production blocks were all over the place and the factory actually had a fixture that final honed the bearings true. I build a lot of Chrysler big blocks and its very rare that I dont have some issues with cam fitment. Not a big deal to get it straightened out, but it always needs attention.

MB

One out of four blocks will need work on the cam bearings, install them one at a time and then slide the cam in, fix as needed

Then I've been lucky enough to find the other 75% of them....lol
He hand massaged them last night.....so they're all good now...
Thanks everyone.
Posted By: Leon441

Re: Cam bearing install issue - 02/16/12 02:44 AM

I had never had this trouble until recently with a 360 magnum.

I found the tight spot was next to the oil hole on each journal. I removed all the bearings. Then put a new set in the freezer overnight to shrink them down while cold. Then they pressed in very easily. After the acclimated to the block. The cam slid in just fine.

My assumption was when you beat the bearing in the cam bore with a press fit the bearing swells up. It also scrapes hard across the oil hole and scuffs bearing material pushing the bearing ID out of shape at the oil hole.

Leon
Posted By: Mopar_Rich

Re: Cam bearing install issue - 02/16/12 03:01 AM

They make "bearing knives" just for this. Use no oil and the cam will scuff the bearing shell where it needs to be shaved.
Posted By: blue_stocker

Re: Cam bearing install issue - 02/16/12 03:34 AM

A few years ago (and probably still on his site) Mike Ware at Muscle Motors had a blurp about the cam bearings not fitting 'as-designed' as it has to do with Chrysler's tolerance/alignment problem in the cam tunnel and is quite common. What they do (and I've done as well) is hone the tunnel for proper fit/crush, then...no problem! If you don't want to go that route, get yourself a 3 corner scraper and some prussian blue and scrape them in or just trial fit the cam and scrape until it 'fits'.
Posted By: CompWedgeEngines

Re: Cam bearing install issue - 02/16/12 03:40 AM

Unfortunatelt we are blessed with horrible cam tunnels. As already discussed we have:

1) cam tunnel misalignment
2) bore sizing all over the place
3) thin bearing walls, which distort much easier than say a BBC. You rarely ever have to touch a BBC bearing, as the " cage" is much much more rigid. As mentioned, the thinner BBM bearing shells distort way easier.

Its often the number 4 bearing. Inexperienced installers often seem to crush the #1 and #5 bearings worse as well. If you use an expandable type installer instead of the solid untis, you need to keep the rubber sleeves good and snug so the installation ring isnt bouncing, with really adds to the bearing shell distortion.

Just more of the fun...
Posted By: HPMike

Re: Cam bearing install issue - 02/16/12 04:36 AM

Quote:

Unfortunatelt we are blessed with horrible cam tunnels. As already discussed we have:

1) cam tunnel misalignment
2) bore sizing all over the place
3) thin bearing walls, which distort much easier than say a BBC. You rarely ever have to touch a BBC bearing, as the " cage" is much much more rigid. As mentioned, the thinner BBM bearing shells distort way easier.

Its often the number 4 bearing. Inexperienced installers often seem to crush the #1 and #5 bearings worse as well. If you use an expandable type installer instead of the solid untis, you need to keep the rubber sleeves good and snug so the installation ring isnt bouncing, with really adds to the bearing shell distortion.

Just more of the fun...





I do a lot of small Fords too....Never had any problem with those as well...Just part of the deal.

MB
Posted By: Von

Re: Cam bearing install issue - 02/16/12 05:27 AM

I have a 72 RB that Ive had for over 20 years. This block has major issues with the cam bearings...

First time I pulled a cam out of it, one of the bearings was spun. Had a guy come to my house and put a new bearing in. Tried to put the cam in and had to hammer the cam back in. Didnt know (or care) any better and fired her up. She turned over really slow till it lit. I guess the bearing clearanced itself pretty quickly. Never had another issue with that cam.

Rebuilt that motor a few years later. Sort of forgot about the cam bearing problem... Short block all assembled, try to put cam in block. No fittie. Buddy who was helpin me hammered the cam in and ran a bolt down in the front of the cam. Chucked the bolt in a drill, trying to spin the cam. Worked for a few minutes till the bolt broke in cam. Ended up making a ream with a factory MW cam he had lying around. Reamed all of the bearings and hoped for the best. Never had an issue and the bearings all looked good a few years down the road.

Same block 10 years later. I paid a machine shop to "correct" the block. Machinist told me he had the proper tooling to correct the block. Pick up block and machinist scrapped the bearings to fit the cam. Still no issues, so whatever..

78 RB block in my car at the moment had 2 tight bearings. Reamed them also. No issues with it.

400 block that is going together at the moment has one bearing .001 tight. Gonna hit the cam journal a .001 and call it good.
Posted By: Performance Only

Re: Cam bearing install issue - 02/16/12 06:06 AM

i made a special tool holder that bores the center 3 cam bores in line with the front and rear cam bores one at a time. maybe i ought to mass produce it for what's left of the BB mopars out there. i can tell you that a lot of the problem is sharp edges on the front face of the bores catch the bearing back and gouges the bearings going in, consequently distorting them during installation. aside from that, the cutters in the bar seldom take more than a few tenths from the bores themselves, but it's enough so i seldom ever have to touch a bearing after installion and the cams spin freely with two fingers.
Posted By: B G Racing

Re: Cam bearing install issue - 02/17/12 01:21 AM

Quote:

i made a special tool holder that bores the center 3 cam bores in line with the front and rear cam bores one at a time. maybe i ought to mass produce it for what's left of the BB mopars out there. i can tell you that a lot of the problem is sharp edges on the front face of the bores catch the bearing back and gouges the bearings going in, consequently distorting them during installation. aside from that, the cutters in the bar seldom take more than a few tenths from the bores themselves, but it's enough so i seldom ever have to touch a bearing after installion and the cams spin freely with two fingers.



Dan,are you removing a few tenths from the block bores or the bearing in the bores itself or just the face of the block bores.Tenths seem to be alot, if you remove a few tenths from the block bores,how do you retain the bearing?Maybe I'am misunderstanding
Posted By: CHAPPER

Re: Cam bearing install issue - 02/17/12 01:26 AM

Bob, I'm thinking "tenths" as in .0007"...
Posted By: B G Racing

Re: Cam bearing install issue - 02/17/12 01:38 AM

Quote:

Bob, I'm thinking "tenths" as in .0007"...



Posted By: Performance Only

Re: Cam bearing install issue - 02/17/12 04:36 AM

Quote:

Bob, I'm thinking "tenths" as in .0007"...



exactly right. usually less than that, more like .0003-.0005. also, the sharp leading edge gets a slight chamfer. a lot of those cam bores are as sharp as a razor blade.
Posted By: B G Racing

Re: Cam bearing install issue - 02/17/12 05:16 AM

I agree this is a place for a lot of attention that is usually missed and always corrected at the bearing surface.But as Dan clarified take as little as possible from the block bores.Having a cam bearing spin and ruin a bore or come out and catch in the lifter area can be costly.If we don't think the fit feels snug enough we will put sleeve/retainer seal behind the bearing,especially on aluninium blocks.
Posted By: Performance Only

Re: Cam bearing install issue - 02/17/12 05:23 AM

Quote:

I agree this is a place for a lot of attention that is usually missed and always corrected at the bearing surface.But as Dan clarified take as little as possible from the block bores.Having a cam bearing spin and ruin a bore or come out and catch in the lifter area can be costly.If we don't think the fit feels snug enough we will put sleeve/retainer seal behind the bearing,especially on aluninium blocks.



as far as i'm concerned, all aluminum blocks get loc-tite on the cam bearings at the very least. on blown alky motors running the larger cam cores i normally pin the cam bearings in place as well since they often see 1400+ pound spring loads on a larger bearing surface that could potentially grab a bearing and spin it. it's just a lttle added insurance.
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