Cam durations for all S38/M88's?

[Rich Euro M5]

Thanks Phil.
Always willing to learn something new.

I'm like Rich I have done the US V-8's.
BTW- Rich I have turned my engine backwards as long as the timing chain tensioner is installed. It could skip a link without it.
This is where i have noticed some "play" in the system but figured that it only runs one way so all the slack is pretty much gone.
Can't say it's hurt anything unless it caused these stupid leaks.

I was wondering if the tensioner kept enough slack out of the timing chain to spin the engine backwards. I was thinking about fabricating some sort of attachment for the tensioner body, using all thread to manually keep the tensioner tight against the chain.

Rich

[M5BB]

Hey Rich.
We're just all over the place today.

Please let me clarify that i did not "spin" the engine backwards only turned it some with the crank nut checking for a possible skipped link in the chain. I doubt i ever went all the way around backwards.
Another point is that i am using the updated tensioner from the M3 engine.
It is spring loaded all the time so if you had one you can just screw it in and have tension. None of that waiting for the diaphram to get oil or what ever it was supposed to do.
If you want more info there I can find a link to a write up about it.

[Rich Euro M5]

I should clarify, I don't mean to literally spin the engine backwards. I mean to turn it backwards by hand using the crank nut.

Rich

[M5BB]

Good, I'm glad we understand each other.

[klrskies]

I have a homemade adjustable piston stop that goes in the sparkplug hole to determine Crank TDC on OHC engines.
Ken

[mooseheadm5]

The tools for the M50 series engines include a mechanical tensioner for use when setting the cam timing. If you can use an S50 tensioner in an S38 (you can) then you can use this tool.

[scottiesharpe]

[Devinder]

Are we talking exhaust side here and if we are why would anyone want the exhaust center at 90degrees?

Paul

Like I said, lots of confusion about the meaning of retard vs advance when you talk to people about this. I'll just post my measurements of the sprockets. Based on these measurements, the stock (unmarked) b35 sprockets are both about 105 lobe center.



In this CAD drawing I've shown the location of the dowel relative to the nearest sprocket tooth. The drawing is a view looking at the front of the engine. All measurements were made on a rotary table and should be accurate to about 0.1 degrees. The markings (A, E, A100, etc) are just as they appear on the sprockets. Note that I'm showing 5 different sprockets on the drawing.

The sprockets have 36 teeth so every tooth represents 10 cam degrees or 20 crank degrees. This is important when discussing cam timing because duration numbers and event timings are typically specified in crank degrees, but lobe center spacing is specified in cam degrees.

The S38b38 sprockets are marked E108 and A108 but I've never measured them.

[Devinder]

Devinder, I was also interested in you method of measuring m30 profiles (m10, m20 also). Are you incorporating lash into these measurements and how did you arrive at the 272 number for your 280 Schrick? Most cam manufacturers generate advertised numbers at the trailing (opening) and leading (closing) edges of the clearance ramps (I believe Schrick uses .012 as a checking height), if you go outside those numbers depending on clearance ramp rate the duration numbers will be out of proportion and not a true indicator of the camshafts potential.

Can you post the opening and closing numbers of your 280 Schrick intake lobe and the checking height or heights (@zero lash) you used?

Paul

Paul,

All measurements were done according to SAE J604. I can send you that standard if you don't have it.

All measurements were done with zero lash so I could map the clearance ramps. On the M30, I adjusted the eccentric until the valve was off the seat (and the rocker was on the base circle). The dial indicator was on the retainer and followed the valve movement directly. On the S38, I used a pair of v-blocks on a granite plate to spin the cam. I have a custom tip for the dial indicator made out of a valve shim so the wipe area is the same. I think I posed pictures on this forum at one time; or maybe I sent them to someone. I'll see if I can find the setup pictures.

I agree that the after-market manufacturers use the clearance ramps for specifying duration. I measured duration at the SAE J604 standard height. I forget what it is right now, but it turns out that those duration numbers are very close to BMW's advertised numbers so I think BMW uses the SAE standard. I think the SAE standard height gets you off the ramps. The American after-market cam makers do the same thing by specifying duration at 0.050" lift so you can compare different cams.

Your question about the S38 duration: I would just read it off the chart for whatever checking height you want. I think I've drawn both SAE and American checking heights on the chart.



Keep in mind that the SAE standard calculates the checking height as a function of the manufacturer's lash setting so it will vary for different cams.

Devinder

[paul burke]

The sprockets have 36 teeth so every tooth represents 10 cam degrees or 20 crank degrees. This is important when discussing cam timing because duration numbers and event timings are typically specified in crank degrees, but lobe center spacing is specified in cam degrees.

Devinder, all camshaft timing numbers are measured in crank degrees. When measuring to find duration at a given checking height you WILL find the split of the lobe. This is NOT the install centerline number but simply half the the total offseat time.
Lets say we used .020 as a checking height and found that the opening is 20 degrees before top dead center (BTDC) and the closing is 40 degrees after bottom dead center (ABDC) this intake lobe would have a measured duration of 240 degrees of crankshaft rotation and as measured has an intake lobe center of 100 degrees.

20+40+180=240 degrees

To find the center you first split the measured duration, 240 divided in half=120 (this is not the install center relative to crank position it is simply half the measured duration of the
lobe) to find the true install center 240 in half =120 - opening of 20 =100 intake center. If you count 120degrees (half the measured lobe) from the opening number (in this case) 20degrees BTDC you will land at 100 degrees ATDC in crankshaft rotation. If you count the opposite direction from closing 120 (half the measured dur.) which our test lobe is 40ABDC you will again land at a install center of 100 degrees.

Paul

[M5BB]

So Paul i can see in the chart that the 264 cam begins
it's opening right at the base yellow line.
Is this where the thought comes from about the shims for this cam possibly rocking in the bucket?
So an A100 gear is how many degrees of exhaust cam retard? 5 degrees?
If i am running the CP pistons at 10:5-11-1 is there a way to know if there is valve clearance for the A100 gear and would there be any benefit to this with both the 264 cams with euro headers?
I should have measured the clearance before i installed the head permanently. My bad............

[Devinder]

Devinder, all camshaft timing numbers are measured in crank degrees. ........

Paul,

Here's a perfect example of what I meant. Look at the Hartge cam sheet Charles got. The duration is in crank degrees and the lobe separation is in cam degrees.

Devinder

http://www.mye28.com/viewtopic.php?t=76932

[paul burke]

Devinder, all camshaft timing numbers are measured in crank degrees. ........

Paul,

Here's a perfect example of what I meant. Look at the Hartge cam sheet Charles got. The duration is in crank degrees and the lobe separation is in cam degrees.

Devinder

http://www.mye28.com/viewtopic.php?t=76932

I don't get what your looking at? 108 is the position of the crankshaft in rotation ATDC when the intake lobe is at its measured centerline or max lift center, and if the camshaft is installed by splitting centers (which is the lobe center separation number indicated as 108, this is not a Hartge cam card BTW.) the exhaust center will also be at 108. If your thinking that half the duration ,this lobe being 108.5 is the center thats not the case and is what I tried to explain in my earlier post.

I don't know if this will help or not but here is what the timing on a 217degree @ .050lift intake lobe would look like being install @ 108 center and 7.5 degrees advanced to a 100.5 center

open .5 degrees BTDC
close 36.5 degrees ABDC This would be the install timing for a 108 center

open 8 degrees BTDC
close 29 degrees ABDC This would be timing with a 100.5 center

If Jerry would fill out a cam card completely he would have put these numbers in their respective places.

Paul

[paul burke]

So Paul i can see in the chart that the 264 cam begins
it's opening right at the base yellow line.
Is this where the thought comes from about the shims for this cam possibly rocking in the bucket?
So an A100 gear is how many degrees of exhaust cam retard? 5 degrees?
If i am running the CP pistons at 10:5-11-1 is there a way to know if there is valve clearance for the A100 gear and would there be any benefit to this with both the 264 cams with euro headers?
I should have measured the clearance before i installed the head permanently. My bad............

Gary, Phil is working on a very detailed description of install technique, hopefully all the misunderstanding thats gone on for years about camshafts in the BMW world will be somewhat cleared up. The answers you are seeking should get addressed in the posts.

Paul

[Karl Grau]

If Jerry would fill out a cam card completely he would have put these numbers in their respective places.

Paul

Paul,

In Jerry's defense, I just walked in off the street asking for basic lift and duration numbers. Jerry was kind enough to take time from his paying customers to help me out at no charge. I will have a "complete" card for the cam.

Chas.

[paul burke]

If Jerry would fill out a cam card completely he would have put these numbers in their respective places.

Paul

Paul,

In Jerry's defense, I just walked in off the street asking for basic lift and duration numbers. Jerry was kind enough to take time from his paying customers to help me out at no charge. I will have a "complete" card for the cam.

Chas.

Jerry is a good guy, no bashing meant by that statement. He most likely won't fill it out completely unless you ask him . Not many people take the time to check/degree in their cams and most don't know what the numbers mean anyway.

Paul

[Philo]

I have the write-up completed.., pictures and all.... waiting on Paul to give it his blessing.

[paul burke]

I have the write-up completed.., pictures and all.... waiting on Paul to give it his blessing.

Sorry Phil, I will try to get to it this weekend.

Paul

[Karl Grau]

If Jerry would fill out a cam card completely he would have put these numbers in their respective places.

As promised, here's the complete card.

[Philo]

Paul.., PMed you... Give me a call when you get a chance..

Thanks.

[fewofm]

Are we talking exhaust side here and if we are why would anyone want the exhaust center at 90degrees?

Paul

Like I said, lots of confusion about the meaning of retard vs advance when you talk to people about this. I'll just post my measurements of the sprockets. Based on these measurements, the stock (unmarked) b35 sprockets are both about 105 lobe center.



In this CAD drawing I've shown the location of the dowel relative to the nearest sprocket tooth. The drawing is a view looking at the front of the engine. All measurements were made on a rotary table and should be accurate to about 0.1 degrees. The markings (A, E, A100, etc) are just as they appear on the sprockets. Note that I'm showing 5 different sprockets on the drawing.

The sprockets have 36 teeth so every tooth represents 10 cam degrees or 20 crank degrees. This is important when discussing cam timing because duration numbers and event timings are typically specified in crank degrees, but lobe center spacing is specified in cam degrees.

The S38b38 sprockets are marked E108 and A108 but I've never measured them.

I thought that Devinder's graph explained all of this timing stuff but upon revisiting I have a question that perhaps someone can help me with - I realize Devinder isn't out here much:
Why would the A110 and E110 gears measure up differently? Doesn't seem to make sense unless the intake and exhaust cams are timed/ground differently. On this same note, the E gear and A110 gear, even though consensus is that they apparently 5 (or 4) degrees apart, are the same on the graph.

[Devinder]

Jeff,

The A (exhaust) and E (intake) sprockets for the same engine are different (different dowel location) even though the cams are the same because all of that is determined by the pitch of the chain. One way to think about this is if you made the A and E sprockets the same, then you could only set the timing between the crank, E-cam, and A-cam in very coarse increments. The sprocket placement is determined by the chain pitch but you need to set the cams to better than 10 degrees. This is why the dowel locations vary relative to the nearest sprocket tooth. Maybe someone else has a better way to explain this.

As far as the A sprocket and the E110 sprocket. All I am showing on my drawing is the location of the dowel relative to the nearest sprocket tooth. It is just coincidence that the location is the same on both of those sprockets. It has no other meaning beyond that. In fact if I remember correctly, the A and E sprockets are not interchangeable for other reasons having to do with the distributor drive.

Devinder

[fewofm]

Jeff,

The A (exhaust) and E (intake) sprockets for the same engine are different (different dowel location) even though the cams are the same because all of that is determined by the pitch of the chain. One way to think about this is if you made the A and E sprockets the same, then you could only set the timing between the crank, E-cam, and A-cam in very coarse increments. The sprocket placement is determined by the chain pitch but you need to set the cams to better than 10 degrees. This is why the dowel locations vary relative to the nearest sprocket tooth. Maybe someone else has a better way to explain this.

As far as the A sprocket and the E110 sprocket. All I am showing on my drawing is the location of the dowel relative to the nearest sprocket tooth. It is just coincidence that the location is the same on both of those sprockets. It has no other meaning beyond that. In fact if I remember correctly, the A and E sprockets are not interchangeable for other reasons having to do with the distributor drive.

Devinder

What do you mean "pitch of chain"?

[Devinder]

sorry, chain pitch means the distance between the centers of the pins. You can think of it as the length of the chain segments.

[ronin]

Bringing this one back from the grave. There is some good info here. I don't know if philo or Paul are still on here much, but does someone know if the write up and pictures was ever published somewhere?

Thanks,

Eric

[Pavel]

Curious about the write-up as well.

[M5BB]

Bringing this one back from the grave. There is some good info here. I don't know if philo or Paul are still on here much, but does someone know if the write up and pictures was ever published somewhere?

Thanks,

Eric

Best I remember Paul had done the write up but somehow compromised (lost) the file and was so frustrated that he wouldn't re write it.
Phil wrote something about it but I don't think he ever published it because he was not sure of the accuracy of the facts.
I know I wanted the article as well as all of you.
Paul has had a lot of health issues and is not on here much if at all.

[7krpm]

M5BB, I saw that in another post you mentioned B36 cams and Volvo shims may not be the best combination. Any updates to that issue? I noticed that earlier in this thread, it seems like the B36 cams have not only a larger lift, but also a longer duration, which will place the lobe's initial contact point close to the edge of the shim. What do the e34 M5 guys do for shims? Thanks.

[M5BB]

Sorry, really busy and this slipped by me.

I found my problem many years later when I discovered a valve guide was sticking.
My machinist (not known to me) set the clearance for the exhaust guides the same as the intake. Does not work well. 1.5 for Intakes and 1.9 or 2.0 for exhaust.

The problem shim was a BMW shim so no correlation to the Volvo shims.

I really don't see any reason not to use the Volvo shims.
If you're really worried then you could use a find grinding wheel and camphor the edges of the Volvo shims so they would look and feel more like the BMW shims.

Lots of miss information out there about this subject but I have never had a problem with a Volvo shim.

HTH
GAry

[7krpm]

Thanks Gary. That is helpful. I guess this question fits in this thread…do you run both intake and exhaust b36 cams in your engine? That's a clean engine by the way in your sig.