BB Cam bearing bore honing

Has anyone tried this method that Mike a Muscle Motors uses?

http://www.hotrod.com/articles/mopp-0810-mopar-cam-journal-sizing/

Seems like the best idea instead of manually clearancing or scraping the bearings.

Any know how long it would take to hone a cam bearing bore .006 with the pictured Rigid Lisle 16000 hone with 180 grit stones?

>006 is too much I think the tolerance is .002 for machining on them.Did you have them measured?

My machinist would line bore the cam bearing bores in the block. If need be he locktited the cam bearing. When he was done you could spin the cam with one finger and it turned like you had roller bearings in it.Dave

Link to Clevite bearing catalog. Goto Page 69 for 440 engine bearing specs.

http://www.mahle-aftermarket.com/media/l...gs/eb-40-16.pdf

Not sure about using the front three /6 cam bearings, They are 0.0005 thinner, same cam bore size, and a bit more narrow?

I have honed literally thousands of cylinders with a brush like that and they don't remove more than .0001-.0002 if any.


If th cam line is out, you need to fix it with a line bore. Then you need to get oversized bearings.

I'm almost positive you can not align bore Mopar cam tunnels due to no way of holding both ends for the tool cutters for the different sizes
Every good shop I have had fix the bores uses a rigid hone like the one in the first picture, not a ball hone

QuickD100,
Did your machinist line bore the blocks on Big Block Chrysler's or other engines?? I was told by local machine shops and some who sponsor on this board that a BB Chrysler cant be line bored because the cam bearings ID/OD are stepped.

451Mopar,
Thanks for the link!

madscientist,
Are you also speaking of Line boring a BB Chrysler cam bearing bores? As I stated above other machine shops have stated this isnt possible.

I'm not a machinist and not saying anyone is right or wrong, but I attempted to have local machine shops perform this repair including Mopar specialized machine shops and everyone said they either cant do it because the bores are stepped and/or they dont have the proper equipment.

I did try to call and Email Muscle Motors last week but I haven't heard back from them yet. Hence, my reasoning to try and take on the project myself. The article makes it look rather simple as long as you take your time and "measure twice and cut once"

Thanks to all!

Cab_Burge,

Do you have anymore info that you can share with us regarding this process that previous machine shops have performed for you?

Like what grit of stones did they use?

Did they use honing oil?

Any tips would be appreciated.

Thanks!

The biggest issue is getting oversized bearings. I believe the shop I used to work at has purchased a line bore that will do the job. Just getting bearings. I have to go to town in a couple of weeks and I'll stop by and see. I know he has the tooling to do roller cam bearings. So I can't see why you couldn't line bore a BBM if you can find the bearings.

I can't help you on that , I never watch it done
I use a bearing knife and scrape off the high spots until they don't shine any more once the cam turns easily in that bearing. I install each bearing one at a time and stick the cam into each bearing for fitting before installing the next one

You can pin in the bearing so it will not move like on a rod cap.There are people that can do it boring the cam hole like roush racing but is it worth the trouble.

The issue I see with using a fixtured cam alignment hone, is it would take alot of time to setup the hone for each cam bore step, then knowing how much to hone without multiple tear-down/set-up of the fixture/hone tool to measure the bores?

According to Rick Ehrenberg the factory align-bored the cam bearings, that's why we have so much hassle with fit by simply driving them in and expecting the cam to fit.

It's one set up with however many different cam bores sizes there are.


The finish doesn't have to be honed if the tool is sharp, the speed and feed is correct and you don't crowd the machine.

The one shop that I trusted the most in SO CA( Hollins Auto Machine) told me the problem with the Mopar BB cam tunnels was they where usually undersized from the factory, once he honed them to the proper I.D. the bearings and cams fit fine

The machinist I'm talking about is the same one that came to the rescue on the Moparts Engine Masters entrée and bored and bushed the lifter bores. He's told me a couple different times that he's seen BB mopars that were .020 off the line bore on the cam bearings. And yes the bearings are different sizes but they can still line bored/honed.Dave

What is he using for cam bearings. Not saying you can't get them. Just don't recall ever seeing any of them.

I've seen this done and was done on one of my Mega blocks. At least 2 cam bores were about .0015" undersized IIRC. My machinist made mandrels that fit inside the cam bores that guided the boring bar. When a bore was fixed we had a mandrel made for that one and moved over to the next bore to be opened up.
To be honest the honing method looks scary at best and looks like it would just bell mouth the bore due to lack of control and guiding of the tooling.
AG.

I would never feel comfortable enlarging a bearing bore with an abrasive tool, too much possibility of grit being impregnated in the soft babbit.

I have made many main bearing spacers, both from cast iron and aluminum, and a couple from bearings.

With the aluminum or bearing you don't hone very much. Maybe .0002-.0003 max. Light pressure and a lot of oil.


That tool posted in the first post doesn't remove metal so I have no idea how MM is doing what they claim with that tool.

Anything is possible. All Mike is doing with that hone is going in and opening up each individual cam bore to the proper size......that's easy. If the bore is not round or small, you hone it, not a big deal. Since cams have been in these motors before, you know the tunnel is relatively close and it's just an individual bearing that tight or out of round. This is NOTHING like line honing or line boring the entire cam tunnel. You do one of these two options to straighten or open up and entire cam tunnel. Doesn't matter that the bores are different size because when you line hone or line bore a cam tunnel, you open ALL the bores to a common size and have a custom cam ground. A common size is 50mm. That's big block Ford and bearings are common.

I have a Lisle precision cylinder hone like that hone, Sunnen makes one and I'm sure other good tool company make them and sell them also. I have removed over .0015 taper from more than one block with a torque plate mounted on them Their is a knob on the top of the hone to put pressure on the stones, the more pressure the quicker the cutting. Lisle and Sunnen offer different grit stones also
I quit using mine long ago due to the time involved to get the job done compared to paying a good machine shop to do it on a commercial honing machine

Guess I should have been more clear. I can't see the pic very well in the first post. I clicked on the link and looked at the hone in that link.


The hone they are showing in THAT picture is a monofilament BRUSH hone and will not remove much more than .0002 and you have to lean on it to make it do it.

I realize you can get roller cores with different bearings, but again, in the article, looks like they are using a FT cam. Didn't know you can get a core with different bearings for that.

I have acquired a RIGID Lisle hone like the one I displayed in my original post.

As Cab Burge noted there is an adjustable nut to apply more force/pressure to the cutting stones.

The stones are 180 grit.

So far I have measured the #1 cam bearing bore in the block and it's .006 too small/under chrysler spec.

Can anyone give me a estimated time it would take to open this bore .006? 5 mins, 1 hour, 1 day of the drill motor turning the hone??

IS the block material softer than the cylinder bore material?

If you decide to hone the block make sure and use a spray on lubricant to help flush the metal out and keep the stones clean I use a garden sprayer and a mix of diesel fuel(1 gallon) and 5W 20WT motor oil or 1 quart of ATF as the lube
As far as how long on each cam journal it will depend on how much pressure and RPM your using on each journal Make sure and use a good quality 1/2 inch electric drill motor, not a cheapo 3/8 size EDITED Make sure and stroke it front to back equally so you don't wear a groove into the stones, it would be easier if you had a way to control the stroke length and center the shaft to the hone so it doesn't wobble around a lot while honing
Take your time on the first one, cut a little at a time and the measure again until you get it within .0005 on the small size and go from there
I'm thinking it will not go fast so be patient and take your time, good luck

How many guys use an old cam and cut slots in the bearing journal and run it through and spin it to remove material in the cam bearing?

ME... I do all my stock type bearings that way..
use oil and I spin it with my impact wrench...
the cam only turns 1/2 the engine rpm so mine
only turns 4100 cam rpms... I freshen the engine
but the cam bearings stay.. they look fine

The block is cast, cured and machined as one piece, correct?
You will need to learn on how much preload to use on your hone by hands on testing the preload to make sure it is removing material and not polishing it If it is not slowing the drill motor down under the load compared to unloaded it is probably polishing it instead of removing material
Another thing to check before you continue is the cam to make sure it is NOT bent
Been there, done that Cast iron cores and steel billet cams can get bent, both can be straighten also by a good shop
Don't we love trouble shooting

Me.

I have honed bb mopar cam housing bores before using a hone similar to the one pictured.

The biggest challenge in taking out as much as .006 will be preventing taper or bellmouthing the bore.

It won't take very much honing to do it. Exactly how long will depend on how much tension you put on the stones, rpm, and lube used.

Hone a little.... Check size and taper.... Hone some more, etc.

My understanding of how the factory did it was that there was a 5-step reamer used on the bearings themselves that did all 5 at one time, in place.
So it didn't matter if the factory cam tunnel bores were all that round or perfectly in line with each other....... Being sized in place, all at the same time made it less critical for that part of the block to be really "right".

I've actually gotten sort of burned by a screwed up cam tunnel on these motors before.
You have the block all done, then you go to install the cam bearings only to discover there is some issue with the cam tunnel.
Now, after the block comes out of the cleaner, it's the first thing I check.

Lots of shops use "cutter cams" because it's quick, easy and usually works just fine. But to actually "fix" the issue......honing is the right way to do it.

As fast says, it will likely cut way faster than you think it will. Go slow, check it often

The grooved cam trick has worked great for me.

Most of the tight ones I've found didn't need much. Only ever came across one that you almost couldn't push the cam into the bearings.

on a tight cam bearing you are suppose to put the cam in the freezer and then install it. Just kidding.

The only CORRECT way to do it.