Author Topic: cam sprockets (Read 4678 times)

zav3n · « **on:** May 24, 2007, 04:08:57 PM »

r3vlimtied.com says that our cam sprockets are adjustable on the m42(http://r3vlimited.com/Tech/318is.htm) is this true? All my friends are all m20 and s14 guys and say that it isnt right, id really liek to prove them wrong!... has anyone done this or know if it is true. and/or how to do it...

thanks

-Zav

cecotto · « **Reply #1 on:** May 24, 2007, 05:01:37 PM »

They are adjustable standard. No need for any axtra stuff.

gearheadE30 · « **Reply #2 on:** May 24, 2007, 07:22:15 PM »

Yes, they are adjustible, and i guess the best setup is to advance the intake cam 5 degrees and leave the exhaust alone.

Alpine003 · « **Reply #3 on:** May 24, 2007, 11:35:34 PM »

They are adjustable but a bit worthless considering they have no markings or engravings. You'll need to buy additional tools if you want to get the settings to the exact degree. This is my pet peeve on these M42 sprockets. :rolleyes:

mikko · « **Reply #4 on:** May 25, 2007, 02:46:50 AM »

i�ve tried many cam setups and intake 5 deg advance is�nt setup for me! it gives nice low end but "no" top end after 5000rpm...

intake 5deg advance exhaust 1.5 retard gives very unstable idle and you have to be careful with accelarator pedal cause it has sharpened a lot

it was funny setup but very hard to drive daily

now running:
intake 3deg adv exhaust 3deg retard, nice low end and top end, and it idles nice

and yes, i did use measuring tool

Alpine003 · « **Reply #5 on:** May 26, 2007, 12:51:07 AM »

Quote from: mikko;26533

i�ve tried many cam setups and intake 5 deg advance is�nt setup for me! it gives nice low end but "no" top end after 5000rpm...

intake 5deg advance exhaust 1.5 retard gives very unstable idle and you have to be careful with accelarator pedal cause it has sharpened a lot
it was funny setup but very hard to drive daily

now running:
intake 3deg adv exhaust 3deg retard, nice low end and top end, and it idles nice

How can you tell 1.5degree of retard without any markers on the sprockets. Did you use the measuring tool?

Frankie · « **Reply #6 on:** May 26, 2007, 12:24:01 PM »

What kind of measuring tool, link info?

christophbmw · « **Reply #7 on:** May 26, 2007, 01:01:56 PM »

there is a hole in the bell housing (under the starter), and a hole in the flywheel. the idea is to line both holes up and insert BMW's locking tool.

on the back side of the cams there is a sqaure piece molded to the cam. BMW also makes another tool you use which lines up both cams to the factory setting. if you want to adjust it a 22mm wrench fits fine onto the sqaure moldings and you just "eyball" it (im sure there are better ways). also, make sure you do not get slack in the timing chain on the tension side.

ps. the factory setting is the best setting. i have both retarded intake timing and advanced it. both times trying 2, 3 and 5 degrees. my advise is to leave it stock, sure youll have killer top end, but low end sucks.....and visa versa. also, adjusting the exaust cam wont do a damn thing. just my two cents.

Alpine003 · « **Reply #8 on:** May 26, 2007, 04:15:07 PM »

Quote from: christophbmw;26628

ps. the factory setting is the best setting. i have both retarded intake timing and advanced it. both times trying 2, 3 and 5 degrees. my advise is to leave it stock, sure youll have killer top end, but low end sucks.....and visa versa. also, adjusting the exaust cam wont do a damn thing. just my two cents.

The factory settings are only good assuming you haven't had any headwork done. Shaved heads require different settings which I'm going to start exploring soon.

cecotto · « **Reply #9 on:** May 26, 2007, 07:39:21 PM »

Quote from: Alpine003;26640

The factory settings are only good assuming you haven't had any headwork done. Shaved heads require different settings which I'm going to start exploring soon.

I think thats wrong.

With the factory adjustable sprockets you will get the correct settings regardless of shaved heads.

When timing your engine, the bottom end gets locked into place. And the cams are fixed through a special fixing device. And then the sprockets are tightened up. This way you WILL get the correct timing of the engine.

Had they not been adjustable, you would have been correct.

Alpine003 · « **Reply #10 on:** May 27, 2007, 02:11:21 AM »

Quote from: cecotto;26644

I think thats wrong.

With the factory adjustable sprockets you will get the correct settings regardless of shaved heads.

When timing your engine, the bottom end gets locked into place. And the cams are fixed through a special fixing device. And then the sprockets are tightened up. This way you WILL get the correct timing of the engine.

Had they not been adjustable, you would have been correct.

Yes in theory this would be correct but I'm not sure if the factory timing is optimized to be used with a shaved head. This is the reason why I think this; I recently changed the timing components to a t and double checked everything and worked very carefully and meticulously locking both top and bottom end and also making sure I had the correct number of dowel pin spacings between the arrow markers on the sprockets.

After the changeover, my powerband didn't feel the same as before. Just to make sure I didn't have any bent valves, I did a compression check and checked out fine at 210 across the board. I'm going to play with my timing to see if I can restore the powerband to where it was before. I guess this will either prove or disprove my theory.

kowalski · « **Reply #11 on:** May 27, 2007, 07:29:45 AM »

let us know what you happens as i have a shaved head as well.

christophbmw · « **Reply #12 on:** June 02, 2007, 12:36:30 PM »

if your compresion changes to a higher compresion (from shaved heads) you would want an advanced intake cam right?

Alpine003 · « **Reply #13 on:** June 04, 2007, 10:53:27 PM »

Quote from: christophbmw;26992

if your compresion changes to a higher compresion (from shaved heads) you would want an advanced intake cam right?

Yes, you would want to increase your intake cam timing because the loss in metal of the shaved head reduces the length from your crank to your cams, generally retarding your timing. Now this will only be noticeable if the head has been shaven quite a bit. I'm not sure at this point if it will be noticeable in anything under a .010" shave however.

Just want to clarify with anyone that has done it that advancing the intake cam would involve turning the cam gear clockwise to advance it. Damn history of working on Honda's with reverse motor really confuses me at times.