Jump to content

Schrick 304 Camshaft Set Up Details


Recommended Posts

I am a new forum participant but have experience with the BMW M10 engine.  I purchased a billet camshaft from Ireland Engineering that is a copy of a Schrick 304.  Ireland is unable to supply a cam card which from other cam suppliers would detail all the set up data needed to install and time the cam.  I wonder if anyone has an original Schrick 304 cam card which shows the intake and exhaust lobe centers or high lift points with which to properly set the cam timing.

Link to comment
Share on other sites

No idea how exact a match it is for the Schrick, but here’s the basic Schrick cam specs and install Info.

 

I’d assume it does NOT require the notch/slot in the center journal ala the original.

 

FWIW, Schrick didn’t/doesn’t supply a cam card - but since your cam is from IE maybe they do for theirs? Or dial it in yourself with a degree wheel..

 

I bet one of our builders might have captured cam card-type detailed specs… ? … but I haven’t seen any.

 

Schrick M10 Cams Info.png

2009 Schrick-Cam InstallTech.pdf

Edited by visionaut
sPeLL
Link to comment
Share on other sites

Thanks, this is good info.  I will see how it corresponds to the usual cam card data supplied by the American cam suppliers.  The Ireland version of the 304 is supposed to be an exact copy of the Schrick item.  However, they supply only the basic data, not the info needed to set up allowing for production tolerances between different engines of the same type.

Link to comment
Share on other sites

I have all the cam cards in PDF for Schrick M10 cams. The base circle is cut deep on an over 300º standard journal cam, which means you'll probably need oversized eccentrics or lash caps. I'm sure the cam grinder IE uses knows what he is doing, but without a cam card from the grinder for the profile he's using, you're kind of going on faith.  

Here's the droid you're looking for...no guarantee it matches what you have exactly, sorry.

304 cam card.PDF

  • Thanks 1
Link to comment
Share on other sites

One more thing, you absolutely need an adjustable cam gear with a cam like the 304 in and engine that most likely has had the head surfaced. With a stock gear, assuming the cam was ground correctly, it will almost assuredly be late(retarded). Depending on your head thickness, you may need +2º or more just bring it to 0, which honestly isn't enough. The 304 isn't considered a full race profile, but very aggressive street/autocross/rally. You'll probably want at least +4º assuming the rest of the engine is built to a level to take advantage of this cam.

  • Like 1
Link to comment
Share on other sites

6 hours ago, uai said:

My 304 cam is set to 0° (same lift intake/exhaust at 0°) and it performs well

 

^

A couple of my Schrick 304 race engines are timed at 0°, and they perform well. -KB

 

 

 

Link to comment
Share on other sites

Thanks a bunch for all this great info.  I believe I will be able to get the timing correct with this data.  The head is a late model ('83) and was untouched as was the block ('70's), as far as I can tell.  I am modifying a stock camshaft sprocket for an aftermarket eccentric location 'button' on the mill.  It came with 5 buttons that represent all the advance or retard that I will need, hopefully.  

The Ireland 304 billet has a large base circle and doesn't require modifying the center journal in the head.  It does need the lash caps to adjust the valves, though.  I am used to this and they offer a larger surface for the eccentric.   When I compared the lash caps to the oversize eccentrics the geometry just seems better with the lash caps, at least in my mind.

BMW M10 Adjust. cam sprocket.JPG

Link to comment
Share on other sites

Excellent question.  Someone smarter than me engineered this adjustment.  The stock locating pin is 6mm.  The replacement pin goes through both the sprocket and the cam and has a step up section which is 6.25mm.  This goes inside the adjusting eccentric, therefore the new pin can't fall out of the back of the front cam flange and is held in place with a sheet metal tab which also serves to lock two of the cam bolts, same as stock. 

 

The detail of the pin is too small for my cell phone camera to capture.

Link to comment
Share on other sites

9 hours ago, uai said:

My 304 cam is set to 0° (same lift intake/exhaust at 0°) and it performs well

If “performs well” is what you settle for, you’ll never understand what “performs great” feels like. The back of the field is full of people that settle. Sorry. 

Link to comment
Share on other sites

Hi GT-3, 

While the head is off is the best time to verify TDC on the flywheel is correct. You can put valves in with shortened rocker arm springs so you can push them down with your finger. put cam in and put head on with an old gasket. Find lobe centers at a couple valve off seat positions, .1" down, .2" down, .3" down to know its the center. Measure both valve off seat distances at TDC at overlap to compare with lobe center 44 80 80 44 to see if they are the both equal. You need to slot your cam sprocket holes to use the eccentrics, get it centered to 0. Now you can rotate the motor and at about 30 degrees before TDC, exhaust valve closing push the exhaust valve down with your finger to check valve to piston clearance. Rotate a couple more degrees and check clearance until you find the angle where clearance is the least. You need to know this so you can advance the cam a couple degrees and check valve to piston clearance again and again to find where your maximum cam advance position is with safe valve to piston clearance is. I don't know whats safe for you but .08"-.1" or so. You may find you can't play with cam timing after its assembeled and running without cutting valve pockets in piston deeper. That will lower compression so you don't want to if you don't have to. It will probably run best somewhere between 0 to 6 degrees advanced. My guess anyway. Please let us know what numbers you find in your tests

 

Luke 

Link to comment
Share on other sites

3 hours ago, Furry Camel said:

If “performs well” is what you settle for, you’ll never understand what “performs great” feels like. The back of the field is full of people that settle. Sorry. 

I'd say 180hp is "well" for a carbed 2 Liter street engine with a 304 cam and no modern stuff. I found some torque since then with a different exhaust header and different intake trumpets but haven't been on the dyno again - these are the graphs for two different exhaust headers.

Screenshot (345).png

Edited by uai
Link to comment
Share on other sites

GT-3, 

If you use light valve springs for measuring valve timing you get better results. The regular valve springs are too stiff and valves closing cause the cam to rotate forward. You will notice the cam chain won't stay the same tension as you rotate the motor. You have to hold the cam gear with a wrench to keep it from advancing messing up your measurments. With light springs you can keep chain tension the same holding the gear with your hand. Of course when the motors running it won't be the same as static bench measurments but thats just how motor building works.

 

uai,

That looks like a good strong street or track motor. Can you tell us more what venturi size, intake length and exhaust dimensions to get that blue line? What is your cam timing?

 

Furry Camel,

He already said the bolt lock strips hold the pin. Got any more constructive info or do you just hire the work out and assume your motors better?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...