Wrong size bearings
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From: Williamsburg, VA
Wrong size bearings 
I had a bad cam bearing in the #1 position and decided to replace it with a new one. The motor is still in the car and I do have a cam bearing tool with a short handle to do this with. I went ahead and ordered a set of Dura-bond cam bearings from one of our sponsors. PN: CH-10.
I grabbed the #1 bearing and tried to install it..... no avail, It wasn't going in. I thought it was because of how cold it was around here and the block had contracted a smidge. I tried #5 bearing and the same thing.
I got out my calipers and checked the I.D. and O.D. of the old bearing and each of the new ones. Here is what I discovered:
Old - I.D. 2.175" O.D. 2.327"
New #1 - I.D. "" O.D. 2.334"
#2 - I.D. "" O.D. 2.325"
#3 - I.D. "" O.D. 2.317"
#4 - I.D. "" O.D. 2.324"
#5 - I.D. "" O.D. 2.336"
The Dura-bonds I received are a bit too big (.008" - .010"). Not even pounding the **** out of them will work.....
Has any one else had a quality control issue with bearing manufacturers?
Car info:
2000 Z28, stock bottom end, new top. (so early block with smaller journals 1st Housing Bore: 2.3260 5th Housing Bore: 2.3280)
Call me crazy but the #5 bearing should go being its .001" smaller than what you removed according to your measurements. Maybe you could use a small propane torch and heat the block around the outside of the bearing area to expand it enough to get it in. I would also put the #5 bearing in the freezer for an hour or so right before installing it. This should be all you need to make the #5 bearing fit. How did you remove the bad one?
Call me crazy but the #5 bearing should go being its .001" smaller than what you removed according to your measurements. Maybe you could use a small propane torch and heat the block around the outside of the bearing area to expand it enough to get it in. I would also put the #5 bearing in the freezer for an hour or so right before installing it. This should be all you need to make the #5 bearing fit. How did you remove the bad one?
. My bad. Last edited by JRENIGAR; Mar 8, 2014 at 11:37 PM.
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Are the new bearings perfectly round? I've had problems trying to measure the OD of loose cam bearings, as they tend to be slightly out-of-round.
I would get some fine-grit sandpaper and remove some material from the OD of the new bearing, that should get you to where you need to be.
I would get some fine-grit sandpaper and remove some material from the OD of the new bearing, that should get you to where you need to be.
Before you call someone out on wrong math, you double and triple check your own, at work all night or not.
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From: Williamsburg, VA
Are the new bearings perfectly round? I've had problems trying to measure the OD of loose cam bearings, as they tend to be slightly out-of-round.
I would get some fine-grit sandpaper and remove some material from the OD of the new bearing, that should get you to where you need to be.
I would get some fine-grit sandpaper and remove some material from the OD of the new bearing, that should get you to where you need to be.
I will try working with the vendor first as this seems to be a QC issue from the manufacturer. If that yields the same results then I may try the emory cloth. I'm a little Leary of that though....
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Instead of measuring your old bearing, look up the specs for what the bearing should measure.
The CH-10 bearings are three different sizes which is why the OD's seem to be in .010" increments. The housing bores are the same way.
Are you doing this with the engine in the car?
Cam installation tools have a cone which ensures the bearing goes in straight and not crooked or cocked. If you're doing this in your car and you're swapping the front bearing, how are you making sure the bearing goes in square?
The CH-10 bearings are three different sizes which is why the OD's seem to be in .010" increments. The housing bores are the same way.
Are you doing this with the engine in the car?
Cam installation tools have a cone which ensures the bearing goes in straight and not crooked or cocked. If you're doing this in your car and you're swapping the front bearing, how are you making sure the bearing goes in square?
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From: Williamsburg, VA
Instead of measuring your old bearing, look up the specs for what the bearing should measure.
The CH-10 bearings are three different sizes which is why the OD's seem to be in .010" increments. The housing bores are the same way.
Are you doing this with the engine in the car?
Cam installation tools have a cone which ensures the bearing goes in straight and not crooked or cocked. If you're doing this in your car and you're swapping the front bearing, how are you making sure the bearing goes in square?
The CH-10 bearings are three different sizes which is why the OD's seem to be in .010" increments. The housing bores are the same way.
Are you doing this with the engine in the car?
Cam installation tools have a cone which ensures the bearing goes in straight and not crooked or cocked. If you're doing this in your car and you're swapping the front bearing, how are you making sure the bearing goes in square?
There should be more than .001" press fit. I put .003-.005" press fit in a valve seat insert. Sometimes it takes some good whacks to get the cam bearings in with the block on a stand so I don't think theres anything wrong besides the fact that the block is still in the car. I think "not ideal" might be an understatement.
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There should be more than .001" press fit. I put .003-.005" press fit in a valve seat insert. Sometimes it takes some good whacks to get the cam bearings in with the block on a stand so I don't think theres anything wrong besides the fact that the block is still in the car. I think "not ideal" might be an understatement.
Yeah it does suck that the motor is in the car....... I have to deal with it and there is no way around that. If I had a new bearing with an O.D. of 2.328 - 2.332" I would be golden & on my way to putting this thing back together. I just couldn't risk leaving a bearing this beat up in the motor and causing any catastrophic issues down the road.
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Wow..... So I called the tech line at Dura-Bond and spoke with Allen. He said the measurements I have are correct and that the "GM guys" told them to leave that much in there. I asked him why, and he could not answer that.
.008" seems like a lot of extra material to me..... I can not beat that bearing hard enough to make that fit.
I guess I have to go with another company if that's how they operate.
.008" seems like a lot of extra material to me..... I can not beat that bearing hard enough to make that fit.
I guess I have to go with another company if that's how they operate.
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.008 press fit is insane, It obvious someone doesn't know what they doing. Anything over .003 is TOO FARKING MUCH!
I would make a jig and turn them to size OR try to find the proper sizes. If you press in a cam bearing .005 interference fit the cam journal fit is going to too tight.
I would make a jig and turn them to size OR try to find the proper sizes. If you press in a cam bearing .005 interference fit the cam journal fit is going to too tight.
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I'm kinda curious about all this because I've read about it before. It seems GM has wrong info on these bearings. The is no such thing as a .010 press fit bearing, it just isn't possible. Gotta be some other explanation.
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Indeed... .008 sounds really out there, unless they want a mess. It's a zero tolerance press, but that shouldn't mean you're cramming 10 lb of dirt into a 5 lb sack... I have no problem with Dura-Bond, but used Clevite for so long, I generally consider those right off and I'd think you could get a set today from NAPA. Maybe not... I quit building engines many moons ago.