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Old 12-27-2012, 03:02 PM   #46
RGregor OP
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Measurement results

Measured the cams today.

The bad news first: my 336 is exactly like MS reported.

Measurement setup/procedure was:
Cam was fixed in a lathe on the sprocket side.
A gauge (resolution 1/100 mm) was fixed on the carriage and oriented towards the top of the lobes.
Prior to measurement the top of the lobe was determined and the gauge set to zero.
For each lobe measurement started from the back side (oil pump side) and measured height difference between back and front edge of the lobe. Positive numbers meaning height is increasing.

Measurement were performed starting with the back lobe (right intake) and ended with the front lobe (left exhaust).

We measured three different cams: the 336, the Andrews cam I bought recently and a worn Schleicher Ro 340.10 (330).

The data gathered are (all in mm):
(Measurement was performed from right to left)

Cam
left ex
right ex
left in
right in
Andrews
-5/100
+5/100
-5/100
+5/100
336
-12/100
0
-12/100
0
330
-13/100
+10/100
-9/100
+11/100



Sad to say the measurement proved the results I got with the vernier (but did not trust completely). Simply by measuring lobe height at both edges of a lobe you can say if the lobe is tapered (heights differ) or not.

I'll give the cam back. As long as I still have it: any suggestions what to measure or how to document that stuff welcome.

RGregor screwed with this post 12-27-2012 at 04:01 PM Reason: put data in a table; corrected "-" signs for 336 and Andrews cam
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Old 12-27-2012, 03:33 PM   #47
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Great heads up. It's easy enough to measure. Even the best of cam manufactures produce bad cams. That's why most all give verifiable specs with their cams as far as checking the timing of the grind. No specs about the lobe's taper though! I am still hoping that was not made in China. The markings are almost identical to my German made 336 although Germans have never been known to make a bad batch of anything!

Now the real test is take it back and order another one and see if it is the same! I wonder if Moorespeed's was a points cam too?

I got two bad crank roller bearings in a row a few years ago.
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Old 12-27-2012, 03:59 PM   #48
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Quote:
Originally Posted by supershaft View Post
Great heads up. It's easy enough to measure. Even the best of cam manufactures produce bad cams. That's why most all give verifiable specs with their cams as far as checking the timing of the grind. No specs about the lobe's taper though! I am still hoping that was not made in China. The markings are almost identical to my German made 336 although Germans have never been known to make a bad batch of anything!

Now the real test is take it back and order another one and see if it is the same! I wonder if Moorespeed's was a points cam too?

I got two bad crank roller bearings in a row a few years ago.
I'd prefer that it had been produced in China ...

My cam is not a points cam but the latest/later style.

I'm not sure how to argument to give it back and order another one.
And to be sure not to get the same one back.
Can't believe it will make sense to discuss taper with the guy at the desc ...
I'll think of it.
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Old 12-27-2012, 04:25 PM   #49
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Quote:
Originally Posted by RGregor View Post
I'd prefer that it had been produced in China ...

My cam is not a points cam but the latest/later style.

I'm not sure how to argument to give it back and order another one.
And to be sure not to get the same one back.
Can't believe it will make sense to discuss taper with the guy at the desc ...
I'll think of it.
Why would you prefer it manufactured in China? Do you really think a batch of mis-ground cams have never come out of Germany?

Your cam isn't a points cam? The points cam that you posted a picture of? Oops! That wasn't your post.

The cam is covered under warranty for the mis-grind. Talk to the parts manager and show him with a caliper. I have warrantied tons of stuff thusly. Like I said, I recently had to order a part a couple of times in a row to get a good one. I got a good one the third time.
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Old 12-27-2012, 05:21 PM   #50
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Quote:
Originally Posted by RGregor View Post
Can't believe it will make sense to discuss taper with the guy at the desc ...
I'll think of it.
Thanks for relating your efforts and posting the results of your inspection.
Regardless of where the cam was made, it is unfortunate the discrepancy was not caught by some form of quality control prior to release.

regarding the 'guy at the desk'... showing your charted data may be helpful.
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Old 12-28-2012, 01:25 AM   #51
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Quote:
Originally Posted by supershaft View Post
Why would you prefer it manufactured in China? Do you really think a batch of mis-ground cams have never come out of Germany?
I just forgot the smily.
Wherever that cam was made it's scrap :-(

RGregor screwed with this post 12-28-2012 at 01:50 AM
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Old 12-28-2012, 02:05 AM   #52
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Quote:
Originally Posted by BOETJE View Post
Have you taken the run out of the camshaft in the lathe into consideration ?
Don't understand what you mean with "run out".

Quote:
Originally Posted by BOETJE View Post
and also : I think you have to screw a flat plate on the dial gauge pointer so it doesn't matter if the cariage rides up or down a bit : if you have a point contact it follows the contour of the cam lobe too easy when you move the cariage around. Not sure if I explain myself good enough here..or maybe you already did this...
No, I did not. The gauge has a relatively small ball at its tip.
But I doubt there was a problem. Measurements could be reproduced several times with changing cams in between.
Measurement of the other cams was done to check if there was a systematic problem with the measurement setup.

Checking contact area with prussian blue may be a good idea.
But I'm definitely not the expert to interpret the results here.

I had talked to some people with a lot of experience and all said: without taper the cam will fail.
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Old 12-28-2012, 04:41 AM   #53
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Quote:
Originally Posted by RGregor View Post
Don't understand what you mean with "run out".
run-out = the part wobbles in the lathe when turned.
the aternate of running true.

I believe the two zeros in your table are enough to rule out run-out
meaning to say, for those two zeros to be present with the other numbers, the part would necessarily run true when turned.

anyway, the results confirmed the story told by the vernier earlier.
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Old 12-28-2012, 05:11 AM   #54
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Quote:
Originally Posted by Renner View Post
run-out = the part wobbles in the lathe when turned.
the aternate of running true.

I believe the two zeros in your table are enough to rule out run-out
meaning to say, for those two zeros to be present with the other numbers, the part would necessarily run true when turned.

anyway, the results confirmed the story told by the vernier earlier.
Ah, I see. Thanks for explaining.
I don't think that was an issue here.
The cam was tensioned in the lathe and stabilized with the tailstock.
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Old 12-28-2012, 06:01 AM   #55
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So now you know the problem is just as richie said it was what's the way forward with it? BMW will obviously keep selling these cams until they're all sold which means there's going to be a lot if air headers that are going to get there fingers burnt. I would imagine that any cams returned will simply be sold onto the next unsuspecting customer. The obvious thing to me is to find some way of letting them know that it's common knowledge that they're selling duff cams.
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Old 12-28-2012, 06:57 AM   #56
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Perhaps I am misunderstanding the problem, but it seems to me there are two options:

1. Put the cam back in the lathe, align the cam, and carefully grind a taper on the four lobes using a tool post grinder.

2. Return the cam to the BMW shop and tell them there is no taper on the lobes. If they give the typical 'blank stare', take a moment to point out that the cam uses flat tappets and the lobes must be tapered.

Getting another cam will involve taking the same measurements. If you can't find a cam with the tapered lobes, then you will need to grind the taper (if you want to use that cam). If grinding the cam seems beyond your comfort level, there may be a cam shop you can talk with to grind the lobes for you. But, of course, that adds expense and time to an "Official BMW' part which should not need extra work. Good luck!
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Old 12-28-2012, 07:09 AM   #57
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if/when I buy a cam across the counter I'll certainly bring a straight-edge and calipers.

from what I've read here, both can be used to verify the requisite rake in the cam profile.
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Old 12-28-2012, 08:13 AM   #58
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Yellow Bag Cam Update

The 'Yellow Bag' cam I posted pics of earlier looks like it is OK. 0.3mm difference on each lobe. Measurements were done by hand with a caliper, so take the number for what it is worth. P/N 11311258053, Small Seal. I ordered it from Chicago BMW in Feb 2009. It was not in stock in North America and took about 4 weeks to arrive from Germany.


Pictures below are of P/N 11311263412, Large Seal 336 degree cam. This was ordered in Oct 2011 from BMW of Countryside, IL. Not in stock in North America and took about 4 weeks to arrive from Germany. The right side lobes have no taper. The Left Ex 0.3mm difference, Left In 0.2mm difference. Again, measurements done by hand with a caliper.


When I intially ordered the large seal cam, the parts guy unintentionally ordered the small seal version. When it arrived, it was pacakged the same (yellow bag) as the small seal received in 2009.






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Old 12-28-2012, 11:16 AM   #59
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Quote:
Originally Posted by CraigC View Post
The 'Yellow Bag' cam I posted pics of earlier looks like it is OK. 0.3mm difference on each lobe. Measurements were done by hand with a caliper, so take the number for what it is worth. P/N 11311258053, Small Seal. I ordered it from Chicago BMW in Feb 2009. It was not in stock in North America and took about 4 weeks to arrive from Germany.


Pictures below are of P/N 11311263412, Large Seal 336 degree cam. This was ordered in Oct 2011 from BMW of Countryside, IL. Not in stock in North America and took about 4 weeks to arrive from Germany. The right side lobes have no taper. The Left Ex 0.3mm difference, Left In 0.2mm difference. Again, measurements done by hand with a caliper.


When I intially ordered the large seal cam, the parts guy unintentionally ordered the small seal version. When it arrived, it was pacakged the same (yellow bag) as the small seal received in 2009.









Great input CC! We are getting further down the road. Good cams come in yellow bags too just as I would suspect and not all newer 336's are mis-ground. Parts have been coming in bags like that for decades if I remember right. The markings and the cam itself looks just like the German made ones. I am still hoping they are made in Germany since I think they will be overall a better product versus made in China.

supershaft screwed with this post 12-28-2012 at 11:34 AM
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Old 12-28-2012, 11:23 AM   #60
supershaft
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Originally Posted by Rob Farmer View Post
So now you know the problem is just as richie said it was what's the way forward with it? BMW will obviously keep selling these cams until they're all sold which means there's going to be a lot if air headers that are going to get there fingers burnt. I would imagine that any cams returned will simply be sold onto the next unsuspecting customer. The obvious thing to me is to find some way of letting them know that it's common knowledge that they're selling duff cams.
I don't think BMW resells there warrantied parts. Half the time they never request them back. I think BMW has sat on and absorbed many a bad run of parts once they figure out what is going on which may be never but not always.
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