117 cam timing - PeachParts Mercedes-Benz Forum

pmckechnie · #1 09-15-2011, 11:41 AM

Has anyone expermented with cam timing on a 116/117 engine? The spec for my 500SEL is the #1 intake valve opens at 20 deg ATDC. For some reason this doesn't make much sence to me. I thought the intake opened around TDC just after or just before the exhaust valve closes. The range for the 116/117 engins is from 12 deg for the 450 to 27 deg for the 560. What I would like to do is move the torque ban down a little. For instance, my car really starts pulling at around 2500 RPM and continues until 5000+ rpm. At 70 MPH, the engine is right at 2500. I would like to lower the max torque by at least 1000 rpm to get 2500 within the max torque range. I really don't need a car that will run 140+MPH but instead run 70 to 80 and be a little more responsive. The engine is actually a Euro engine in a US car. It runs great but loves gas. The best MPG I ever got was a trip from NC to FL and was running with a group of 18 wheelers at 80 to 90+. That tank I got 22 mpg, and the car was as happy as it could be.
Anyone have any thoughts on the subject?

Paul

JayRash · #2 09-15-2011, 04:55 PM

U can buy the cam adj pins made for 4deg change and set the cams 4 deg advanced

Strife · #3 09-15-2011, 06:26 PM

I have been told by a very experienced MB shop owner than 3 degrees of advance is worth "performance you can feel" on a 380.

Actually, I will be seriously degree-wheeling and 3 degree advancing my spare 380SL engine. I suspect that there are very few running MB engines that are truly 0-0. This is definitely robbing some potential.

JayRash · #4 09-15-2011, 09:31 PM

4 deg advance will give u an almost 1000rpm lower shift in power band and increasing low down power

pmckechnie · #5 09-16-2011, 08:41 AM

Jay, Thank you very much for the info. That is exactly what I want. However when I look up offset keys on World Pack, they list the keys as 4 deg at CAM and 4 deg at the CRANK. Which do I need? I know cam timing is usually measured at the crank but in this case (and the way they are listed on WP) I wasn't sure which to get.

Thanks again

Paul

JayRash · #6 09-16-2011, 10:27 AM

Just get what they offer as 4deg adjustment. I ordered them once for
My m110 and it made a huge diff. Also order the 3deg in case u want a diff setting

pmckechnie · #7 09-24-2011, 06:08 PM

Just an update. Installed 4 deg cam keys which is 8 deg at the crank. Looking at some specs I found in Alldata, that makes the cam timing the same as the 420. Low end response is much better. 80 mph response is much better. Power down some after 4500 rpm but not much. I will report back with MPG after a few tanks.

Paul

crishmac · #8 10-01-2011, 01:11 AM

If the plate loosens up you'll go out of time. If the trigger cup/plate loosens up you'll probably just smash the pickup/sensor until it just doesn't work. Both scenarios are obvious on inspection. To manually adjust follow S&S instructions which are roughly get front piston to just before TDC, take out timing plug, rotate until TB/TD???? whatever is in center of hole, then turn on key and rotate timing plate until Thunderheart light goes on.

PanzerSD · #9 10-01-2011, 02:20 AM

Quote:

Originally Posted by pmckechnie

It runs great but loves gas. The best MPG I ever got was a trip from NC to FL and was running with a group of 18 wheelers at 80 to 90+. That tank I got 22 mpg, and the car was as happy as it could be.
Anyone have any thoughts on the subject?

Paul

22? That's pretty damn good...

PanzerSD · #10 10-01-2011, 02:26 AM

Quote:

Originally Posted by pmckechnie

Just an update. Installed 4 deg cam keys which is 8 deg at the crank. Looking at some specs I found in Alldata, that makes the cam timing the same as the 420. Low end response is much better. 80 mph response is much better. Power down some after 4500 rpm but not much. I will report back with MPG after a few tanks.

Paul

How is the idle after those changes? I'm doing the Cams in my 4.5 soon and also want to get my low-mid range power tweaked up a bit.. Mechanical cams ( yes I know the differences) from a 117.983 going into the 117.986. should add 20-25HP just by doing that, along with a new timing chain of course.

pmckechnie · #11 10-01-2011, 01:51 PM

PanzerSD,
I have only put about 50 miles on the new cam timing so far and can tell you, the car drives much better. Now I didn't say it had more power, just more response. Idle is smoother and quieter. I didn't even have to adjust mixture or ign timing. The torque comes on sooner making it feel like it has more power but WOT is about the same after 2500 rpm. Going on a little trip tomorrow and will let you know about mpg. I am hoping it will be better. My normal trip mileage is around 18 mpg at 70 to 75 mph. The 22 i got was at a much higher speed. I hope lowering the torque band will help get the engine in a more effecient rpm.
The only drawback so far is that the car does not like to go less than 40 mph. This is not because it idles to fast, just that the throttle is to touchy.

For drivability, I highly recommend the cam timing change.

Paul