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Old 09-28-2013, 07:49 PM   #1
blaine.hale OP
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cam shaft check

1974 r90 cam saft. There's a little knick where one of the followers goes. There's approximately 100k mile on this cam. Still think it's usable? I'm looking to throw it in my r90 with 64k miles as the tip on my cam sheered and the drill/tap of a bolt isn't as centered as I'd like it to be.

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Old 09-28-2013, 09:44 PM   #2
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Quote:
Originally Posted by blaine.hale View Post
1974 r90 cam saft. There's a little knick where one of the followers goes. There's approximately 100k mile on this cam. Still think it's usable? I'm looking to throw it in my r90 with 64k miles as the tip on my cam sheered and the drill/tap of a bolt isn't as centered as I'd like it to be.
Looks like erosion on the top of the lobe. It's toast.

Wanna buy a cam?
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Old 09-28-2013, 10:01 PM   #3
motu
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By the wear marks the follower isn't running on that part of the cam. If it was my bike, that nick wouldn't be there, and the cam would be in my engine.
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Old 09-29-2013, 01:48 AM   #4
disston
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Judging from that photo I'd agree with Motu and run that cam. A couple more photos would be nice tho if you could get a little different angle. Or better focus (I have the same problem making these Macro photos. Do we have a thread here somewhere about taking photos?)
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Old 09-29-2013, 03:43 AM   #5
chasbmw
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There has be a reason why that cam was removed from its engine and I think that you are looking at it. Have you seen the follower that ran on that lobe?

Your choices are:
Put back to your old cam, you could leave it as it is and go to an electronic ignition, Boyer on the cam or an alternator mounted ignition.

You could fit the 320 degree small seal cam available new from Motoren Israel

Buy another secondhand small seal 308 degree camshaft
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Old 09-29-2013, 04:01 AM   #6
JonnyCash
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That's what the camshaft of my 75/5 project bike looks like. I deliberated on using it, or even TIG welding some silicon bronze into the crater, but Pokie is sending me a good one. On my bike the lifters were beat, each one of them.
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Old 09-29-2013, 04:09 AM   #7
JonnyCash
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Looking at it some more, it really does look like the lifter doesn't even bear on it there. What about filing or grinding the chip smooth with a dremel, and stay out of the contact area? That would help prevent further chipping, and make it easier on the lifter if it does contact.

Or just come up with another camshaft.
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Old 09-29-2013, 07:01 AM   #8
blaine.hale OP
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Quote:
Originally Posted by chasbmw View Post
There has be a reason why that cam was removed from its engine and I think that you are looking at it. Have you seen the follower that ran on that lobe?

Your choices are:
Put back to your old cam, you could leave it as it is and go to an electronic ignition, Boyer on the cam or an alternator mounted ignition.

You could fit the 320 degree small seal cam available new from Motoren Israel

Buy another secondhand small seal 308 degree camshaft
The cam was removed by me ;) I'm already on a boyer, my option is a crank mounted expensive ignition and still have an unbalanced cam, possibly causing issues...or replace the cam and be worry free.
I might try to find a 336 cam or better stock replacement at this point. Anyone have any price gauges on a 336 and a location to buy? I've checked out MI...woo, spensive! I also like the idea of a 324 cam.
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blaine.hale screwed with this post 09-29-2013 at 07:08 AM
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Old 09-29-2013, 07:32 AM   #9
blaine.hale OP
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This one matches the part number of the one I pulled out of the spare block but I heard something about bmw using a larger front seal on the cam after 75? Did the part number remain the same?

http://www.ebay.com/itm/1976-BMW-R90...ad3ab2&vxp=mtr
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Old 09-29-2013, 10:06 AM   #10
disston
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Hey Blaine,

Only thought of this today. It may work. We have talked about it but nobody I know of has tried it yet.



The tip of the camshaft is called the quill and it is removable. You need a press to do this. You have one original camshaft with damaged tip, broken threads, of the quill. And a replacement camshaft with damaged lifter lobe?

My only reservation is about the fit of the quill in the bore of the camshaft. This would have to be checked. It may need matching or they may already match. I don't know.

As far as changing from one size seal to the other I think there's a difference in the cover?
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Old 09-29-2013, 11:15 AM   #11
Stan_R80/7
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Quote:
Originally Posted by blaine.hale View Post
1974 r90 cam saft. There's a little knick where one of the followers goes. There's approximately 100k mile on this cam. Still think it's usable? I'm looking to throw it in my r90 with 64k miles as the tip on my cam sheered and the drill/tap of a bolt isn't as centered as I'd like it to be.
With the r90 camshaft out of the engine, it can be placed in a lathe and the hole bored true and then tapped for a M7x0.75 or M8x1 thread. The final solution may require a custom threaded stud with a M7x0.75 threads on the cam end and M6x1 threads for the advance.

Honing around the nick area helps but it looks like there is another issue on the lobe with that cam: but that may be from the photography. Good luck!
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Old 09-29-2013, 01:40 PM   #12
chasbmw
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Quote:
Originally Posted by blaine.hale View Post
This one matches the part number of the one I pulled out of the spare block but I heard something about bmw using a larger front seal on the cam after 75? Did the part number remain the same?

http://www.ebay.com/itm/1976-BMW-R90...ad3ab2&vxp=mtr
My June 75 is a Small seal cam......I don't think that the Boyer will be much Bovvered by the securing bolt being slightly off centre. I would run the original cam and check the Boyer timing with a strobe. I think that you will find it works OK
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Old 09-29-2013, 05:13 PM   #13
blaine.hale OP
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It does work just fine. Timing has been checked many times. Really I'm being paranoid but I think things that aren't perfectly centered and balances will cause issues in the long run. Plus, if I could get a 336 for under $200, I'd be extremely pleased. I'd love to extract the quill and press it into my existing can but I have no idea how to begin with that. Buying a full replacement might be much easier. 336 hunting time! I'm in no rush BTW. I've got the r75 where I want it :)
I'm pulling the heads and pistons on the r90 tomorrow and soda blasting the stupid amounts of carbon Then balancing the con rods.
Fred, I'll be asking to borrow your fancy scale soon :)
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Old 09-29-2013, 06:41 PM   #14
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Originally Posted by disston View Post
Hey Blaine,

Only thought of this today. It may work. We have talked about it but nobody I know of has tried it yet.



The tip of the camshaft is called the quill and it is removable. You need a press to do this. You have one original camshaft with damaged tip, broken threads, of the quill. And a replacement camshaft with damaged lifter lobe?

My only reservation is about the fit of the quill in the bore of the camshaft. This would have to be checked. It may need matching or they may already match. I don't know.

As far as changing from one size seal to the other I think there's a difference in the cover?
I'm posting this in hope of keeping any one from being injured. I have removed the quill from a cam by heating the front journal of the camshaft. I expected to have to ease the quill out with a plier. Instead, the quill shot out of the cam and into a 25 foot ceiling. I shudder to think what might have happened were I not so lucky.
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Old 09-29-2013, 06:44 PM   #15
JonnyCash
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I've got a few junk camshafts, and now I know what I'll do with them. This is gonna be fun!
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