Cam durations for all S38/M88's?

[BDK]

Does anyone have the Lift/Duration numbers for the

M88B35
S38B35
S38B36
S38B38

???
Just wanting to update my info please...

[Rich Euro M5]

Does anyone have the Lift/Duration numbers for the

M88B35
S38B35
S38B36
S38B38

???
Just wanting to update my info please...

Brad,

Off the top of my head I can tell you the duration numbers for everything but the 3.8liter engine.


M88/3 264 degree
S38B35 248 degree
S38B36 264 degree different base circle than the M88 cams

If I run across any additional info I'll post it.

Rich

[BDK]

Thanks Rich!

[Devinder]

I just finished measuring my new Schrick 280:

b35 248 duration, 10.3 mm lift
b36 264 duration, 10.7 mm lift
Schrick 280, 11.0 mm lift (it's actually 272 duration when compared at the same lift as stock cams )

dont have a b38 or m88 to measure

[rcbmw]

RE: S38B38: 264°/108°, lift 10.7 mm

Best,
RCBMW

[Steve Haygood]

so does the S38 b36 have the same lift and duration as the M88 ?

[Devinder]

Steve,

According to rcbmw the b38 is the exact same cam as a b36 but used with 108 sprockets instead of 110. The M88 has a 1mm smaller base circle so it wont use the same cam as a S38b36 but it may have the same effective numbers.

If someone can send me an M88 cam and sprocket -- I can get all the numbers.

Devinder

[Steve Haygood]

My experince and understanding is that :

An M88 cam does not fit in an S38 E28
The S38 E34 cam will work in an S38 E28

If the cam sprockets have a different number of teeth, then I've learned something as I have installed S38 sprockets in an M88 engine before and have not noticed that.

Corrections ?

[Boru]

No matter what, the cam sprocket has to have twice the teeth of the crank sprocket on a 4 cycle engine.
I assume the "108" and "110" are part numbers.

[Rich Euro M5]

My experince and understanding is that :

An M88 cam does not fit in an S38 E28
The S38 E34 cam will work in an S38 E28

If the cam sprockets have a different number of teeth, then I've learned something as I have installed S38 sprockets in an M88 engine before and have not noticed that.

Corrections ?

Steve,

The M88/3 cams are the odd animals with the smaller base circle. You can use the M88 cames in an S38, but they require the use of caps on the valve stems to take up the extra 1mm of clearance. The opposite is not doable though as the larger basecircle of the S38 cams prevents them from fitting inside the cambox of the M88 engine. Actually, it's the narrower shim puck diameter in the M88 engine that causes this limitation.

All the cam gears have the same number of teeth, the difference is in the placement of the dowel pin which changes the timing of the cam.

HTH

Rich

[Devinder]

All the cam sprockets have 36 teeth because the crank hub has 18. The numbers I used refer to the installed lobe centerline which controls, among other things, the overlap. All sprockets except the early S14, S38b35 and m88 are marked with the installed centerline. I have a bunch of sprokets that I've meaured to figure out what the b35 setting is. Turns out the b35 (and early S14) with the unmarked sprockets are set at 105 degrees. The s14 evo that is used as an exhaust "retard" for the s38b35 says 100 on it. The b36 sprockets are labelled 110, and the b38 sprockets are labelled 108.

This is probably more information that Brad wanted but I thought I'd get it out there since I'm in the middle of choosing the cam timing specs for my new engine. I think I'm going to go with Schick 280 cams and 110 sprockets.

Devinder

[klrskies]

It's been a while since this active, but I'd be intrested to know how that cam gear/ cam combination performed. are you useing a header?

regards,
Ken

[Rich Euro M5]

It's been a while since this active, but I'd be intrested to know how that cam gear/ cam combination performed. are you useing a header?

regards,
Ken

Ken,

Devinder doesn't spend much time on the forums any longer. It would probably be best if you PM or email him for the information.

Rich

[derrith]

It's been a while since this active, but I'd be intrested to know how that cam gear/ cam combination performed. are you useing a header?

regards,
Ken

I spent some time with Devinder and a warsteiner or two yesterday. We took a look at my m5 and found it has a s14 Evo exhaust gear. Devinder explained that there are
two ways to install it. One way advances by 5 degrees, leading to a peakier engine but sacrificing low end. This is what dinan did. The other way retards by 15 degrees, gaining much more midrange power and torque but leading to an engine that peeters at high revs.

To answer your other questions, Devinder's engine is still in pieces at his shop.

[paul burke]

Devinder explained that there are
two ways to install it. One way advances by 5 degrees, leading to a peakier engine but sacrificing low end. This is what dinan did. The other way retards by 15 degrees, gaining much more midrange power and torque but leading to an engine that peeters at high revs.
.

I usually don't react to post like this but holy crap how could one possibly arrive at this conclusion. Please elaborate.

Paul

[derrith]

Devinder explained that there are
two ways to install it. One way advances by 5 degrees, leading to a peakier engine but sacrificing low end. This is what dinan did. The other way retards by 15 degrees, gaining much more midrange power and torque but leading to an engine that peeters out at high revs.
.

I usually don't react to post like this but holy crap how could one possibly arrive at this conclusion. Please elaborate.

Paul

Sorry Paul,

I'm just reiterating what I remember Devinder telling me yesterday. It was over a few beers so my memory may be foggy. What's the issue with what I said?

[Devinder]

I've seen the A100 cam sprocket installed both ways. There might be some confusion over terminology. I'm using "advance" to mean cam events occurring earlier in the crank cycle.

Stock cam sprockets are 105 lobe center spacing. If you install the A100 sprocket properly, it will advance the exhaust by 5 degrees relative to the stock setting.

People advertise this cam sprocket as an "exhaust retard" gear and the only way to do that is by skipping a chain link and installing it so that it retards the cam by 15 degrees. (Because you get 20 degrees per tooth)

Here's one example -- Korman shows an A100 sprocket and says it retards cam timing: http://www.kormanfastbmw.com/m5m6eng.htm

[paul burke]

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

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

[fewofm]

Just when I thought I was getting a handle on all of this!

[Philo]

Lol.. , I understand this perfectly.. Actually, Paul has been helping me behind the scenes with my S38 build. I **was** going to install a custom intake cam as per the grinder's recommendations.., but Paul insisted I check the cam center and it's a good thing I did. My intake was off by 7 degrees.., so we then checked the exhaust it was off by about 12 degrees. The intake cam gear got slotted last week.., and now the exhaust gear will be slotted as well.

I'm now wondering how the cams on my daily driver engine is timed. Great.., one more thing to stress over at night !

Thanks Paul !

[Rich Euro M5]

Lol.. , I understand this perfectly.. Actually, Paul has been helping me behind the scenes with my S38 build. I **was** going to install a custom intake cam as per the grinder's recommendations.., but Paul insisted I check the cam center and it's a good thing I did. My intake was off by 7 degrees.., so we then checked the exhaust it was off by about 12 degrees. The intake cam gear got slotted last week.., and now the exhaust gear will be slotted as well.

I'm now wondering how the cams on my daily driver engine is timed. Great.., one more thing to stress over at night !

Thanks Paul !

So your saying with stock S38B36 cams and sprockets, the cams are not on exact specified centerlines for the gear used ?

If so, I'll need to get in contact with Paul for the test procedure. I've never degreed cams on a DOHC engine, only OHV pushrod V-8s.

Rich

[klrskies]

Do all the cams being discussed have symetrical lobes, opening side to closeing side?

regards,
Ken

[Philo]

Rich.., long time, how are ya.

Note.., this is on my custom engine. Paul explained that custom cams ALWAYS need to be checked for proper lobe center. In my situation.., I have a custom intake cam, pistons, crank.., and a new head gasket that is slightly thicker then the one that the factory put on the engine. I checked the intake cam and it was way off.., so I checked the exhaust and it was worse. Paul commented that if I installed the cams as-is the engine would be dead on the bottom end. Not good for a street car. Definitely get with Paul about the test procedure.

Hey.., if you still need that SLS module PM me. I finally found it.. It's only been 2 years

[M5BB]

I want to hear more............

[fewofm]

+2 on hearing more.

[Philo]

Paul.... time for a little Cam Timing 101.

[Philo]

Talked to Paul today.., he's swamped with engine work and can't take the time for a cam tutorial.. He asked that I post some pictures of my project and what I had to do to check the cam timing. As soon as I get my exhaust cam back from being slotted I'll take some pics and post.

Paul assures that he'll join in with some color commentary.

[Rich Euro M5]

Philo,

As I mentioned earlier, I know how to degree a cam in an pushrod V-8. One question I have is how to properly determine TDC and set the degree wheel on a OHC engine. Typically I would mount the degree wheel and then use a piston stop on the No1 piston, with the heads off, to determine the true zero degree point of the crank. A problem I see using the piston stop method, a pushrod V-8 can be turned backwards without issue. Is it OK to turn a BMW OHC engine backwards? I think not, but maybe I'm wrong. If we cannot turn the engine over backwards there has to be another method for finding the true 0 degree point of the crank. Another major difference, when I degreed cams in pushrod V-8s, I only installed the No 1 piston and the camshaft. This was mainly to reduce drag and make it easy to turn the engine over by hand. And as I mentioned already, no heads, since you take the lift readings off the lifters. Can't do this on a OHC engine, since you need the head in place, along with the head gasket, and the whole mess has to be properly torqued down for accurate readings.

I'm very interested in seeing how this is done.

Rich

[Philo]

Should have the cam gear back in the engine this weekend.., will post the technique Paul showed me as soon as I can.

[M5BB]

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.