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Can you ID a cam w/o engine tear down?

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As I tear down my car I'm finding indications of performance upgrades here and there.

BMWCCA sticker on the rear window.  Upgraded carb.  Headers.

 

Is is possible to tell what cam is in the engine without pulling the engine apart?

 

Zach

 

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The stock cams have the number 2 stamped on the rim of the flange.

Aftermarket cams often have information on the nose of the cam, under the sprocket.

I made a wooden block to fit under the sprocket and on top of the upper chain cover, so the sprocket/chain could be slid forward without losing tension on the chain.  I did not find much information on the front of my (non stock) cam.  Just the number 5.  I can probably dig up the post I made, showing the block in use, if that would be helpful.  To make the block, I basically set the edge of a piece of paper on the top of the chain cove and pressed the paper on the oily face of the sprocket.  This made a black print of the sprocket, which I transferred onto a piece of wood, so I could cut out the shape.

 

Another way to tell would be to measure the smallest and longest dimensions of a lobe, to calculate total lift and compare that number to stock.  Mine is apparently more than stock, but less than a 292.  I want a more accurate answer, so I will revisit it at some point.

 

hth

Tom

 

Edit:  Found it:

and a couple of additional photos, just for fun

033.JPG025.JPG

Edited by '76Mintgrun'02

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The various regrinds from the various vendors is another conversation all together.. Schneider, Ireland, etc.  They all had/have their own ID methods, usually on the face of the cam.  

 

 

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I just added "no.5 on flange" to Andrew's search and found my  answer.

 

 The stock camshaft 264 degree is a #2. The exception to this rule is the #5 cam, which has the number stamped on the front "face" of the cam where the timing gear mounts. There is a lot of uncertainty about the #5 CAM, ALTHOUGH i HAVE HEARD IT IS A SLIGHTLY HOTTER GRIND THAN THE #2. Perhaps someone on the board has a definitive answer.

 

Thanks for steering me in the right direction.

Tom

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Back in the day, when we were racing ITB, I heard rumors of 76 MY cars having a different profile...anyone?

George Thielen

74 2002

73 2002tii

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The quote I just posted in blue was referring to '76 (49 state) cars only.

This may be the rumor you are referring to...

 

I also just found a quote from c.d. which made me smile:

" By 1976, BMW had cured all the gremlins, in the 2002, so they stopped making it "

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All you need to get the important info on the cam--lift, duration, lobe separation, symmetry--is a dial indicator with stand and a degree wheel. You might need to remove a few things to fit the degree wheel (water pump, etc), but it can be done in-car and you don't need to pull the camshaft. I'd take measurements at the valve and divide by the rocker ratio (1.3) to get the cam profile data. While this won't give you the cam manufacturer and grind number, it will give you enough info to make a good guess as to what you have by comparing to published cam specs. See post linked below for discussion of this.--Fred

 

 

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Good stuff Fred, thank you.

I made a degree wheel with a 360* protractor, a chunk of dowel and a magnet and stuck it to the sprocket.

040.JPG055.JPG051.JPG

The pointer is made from the stainless 'spring insert' from a wiper blade.

066.JPG

I have the measurements around here somewhere, I think.  I may need to do it again.

Tom

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I understood the 'lift' to be the valve lift, not the cam lobe size.

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38 minutes ago, jimk said:

I understood the 'lift' to be the valve lift, not the cam lobe size.

It can be either. Though if not specified lift usually refers to lift at the valve. 

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I got a cylinder head in a box of parts I bought and I think it was set up to measure valve lift.  The rocker shafts had been cut down short, to hold just two rockers and there were only two valves, with very weak springs on them.  (There were also two fresh reground cams in the box).  

 

It would be easy to measure valve lift in that way, but with the cam still in the engine, how would you measure that, as opposed to getting the lobe dimensions?  I agree that these are two different ways to measure the cam, but don't they answer the ID question, albeit using different dimensions?

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57 minutes ago, '76Mintgrun'02 said:

I got a cylinder head in a box of parts I bought and I think it was set up to measure valve lift.  The rocker shafts had been cut down short, to hold just two rockers and there were only two valves, with very weak springs on them.  (There were also two fresh reground cams in the box).  

 

It would be easy to measure valve lift in that way, but with the cam still in the engine, how would you measure that, as opposed to getting the lobe dimensions?  I agree that these are two different ways to measure the cam, but don't they answer the ID question, albeit using different dimensions?

The way you do it on a 914 is to put the dial indicator on the valve spring retainer and measure how far the valve travels, and then to math to take out the rocker ratio. I would imagine you could do something similar here. 

Zach

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Thanks.  I was wondering whether the indicator could be placed on the 'washer' at the top of the spring and measure its movement.  (I do not want to beat the topic to death...)

 

Does your cam have a number 2 on the edge of the cam?

What year is your minty car?

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Yep,

measure how far the spring retainer travels.  Make sure you're perpendicular to it.

Most aftermarket cams are measured "at zero lash" so that the vagaries of how the

rocker moves are factored out- and so they gain a few thou of 'advertised lift'

 

Thingy is, unless you know who made/ground your bumpstick, it just gives you raw numbers.

Which tell you what the valve's doing, but not what the cam is.  Well, other than 'it's a cam that makes the valves do this'

which is what matters if you are comparing a lot of cams to get the best <whatever you're looking for>

 

A schrick, for example, can then be easily identified.

A delta regrind, however, may not be, even if you know it's a delta since they won't rat out those of us

who give them numbers and then ask that they don't sell the numbers.  If you don't ask that, they will... if you know how to ask,

and are willing to drive to Tacoma. 

 

t

 

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