M130 distributor question

[bracurrie]

While I am committing the sin of modifying an original car, I am trying to stay as original as possible. But the 061 distributor on a 1970 M130 is designed to work with the ignition retardation installed on US import versions is for a very slight emissions reduction. If you remove the system you have to adjust the idle, but other than that the car seems to start hot or cold, run and perform quite well.
My question is would there be any advantage to locating a good 051 distributor like those found on the 68 and 69 versions of the M130 engine?
Thanks
Brad

[Cees Klumper]

For what it's worth, when I bought my 280 SL in 1998, we had trouble getting it to run properly and the final diagnosis was that, with the emissions equipment removed (it is a US model), it really needed the vacuum advance distributor to replace the retard one. That did seem to cure the issue we had at the time. I since replaced it with a 123 unit which most agree will be a good upgrade for all 113's.

[dirkbalter]

If you remove the emission reduction system and switch to a 051 distributor, you will also need a different (earlier) throttle body. The 123 unit may be a better way to go.
(I had the same issue on my 1970 280 SEL, M130 motor with a non-working emission reduction system)

[Tyler S]

Just a note on the 123 and later cars with emissions (70-71). If you are going down that road, spend the extra money and purchase the “123-Tune” with bluetooth. It has the ability to set an RPM trigger point to start the vacuum advance/cancel retard. You can set it anywhere you want such as where the existing system triggered at 2200rpm. It also has the ability to create your own timing map which is different than the older cars, hence why some have trouble with getting the older version of the 123 to work on emission cars with switchgear and the later throttle body.

[Benz Dr.]

Just a note on the 123 and later cars with emissions (70-71). If you are going down that road, spend the extra money and purchase the “123-Tune” with bluetooth. It has the ability to set an RPM trigger point to start the vacuum advance/cancel retard. You can set it anywhere you want such as where the existing system triggered at 2200rpm. It also has the ability to create your own timing map which is different than the older cars, hence why some have trouble with getting the older version of the 123 to work on emission cars with switchgear and the later throttle body.

I agree. You can use whatever system you like but all of the parts need to work together as a complete system. There are three different throttle bodies used on 113's and you must match your distributor to the throttle body. I would not, in any event, disconnect the vacuum line on the late 280SL system if it's still working and expect any sort of improvement. I'm not saying that anyone here is trying to do that but it seemed to be an idea very much in vogue in the 70's when emission systems started showing up. 

" Hey, let's take all of that crap out of there and make it run better! Yeah, that's the ticket! "    

[Shvegel]

Bracurrie
I did just what you are suggesting using an 051 with a Pertronix igniter.  If your car has the vacuum idle compensator you can tee in the vacuum line there.   Use initial timing specs from a 68 or 69 model.  save your 061 as they are SL only and quite valuable to those of us who had them removed at some point.

[Tyler S]

Dan, Yes I would leave a working switchgear system alone as it also controls timing advance when cold or over 200 degrees. It also controls the decel fuel cut solenoid. However, most of the components including the vacuum switching valve, speed, and changeover relays are NLA. The 123 Tune+ effectively has the speed relay and vacuum switching valve built into the distributor so you retain good drivability. Its a good option for a car with missing parts or defective components. However, you loose the high temp advance and the decel fuel cut so there are minor drawbacks. 

[bracurrie]

Thank you to everybody replying to my question.
Tyler,
I also agree with Dan that if the switchgear for vacuum retardation is working leave it alone. Unfortunately mine is not working properly so I am in this "rabbit hole". Its my understanding that the retard setting is cancelled when engine is below 13C and above 212F no matter the RPM. There is no further advance as the removal of retard allowing the distributor to fully advance mechanically as designed for nominal engine operation. I am lucky in that because I have a manual I do not have to rely on retardation to lower RPMs while in N.
I am curious, what is the difference between the throttle bodies that are paired with the 061 versus the 051?
Brad

[Tyler S]

Brad,  The throttle body on the earlier cars with the 051 distributor have a vacuum port just aft of the throttle plate. So that when the throttle is opened slightly, vacuum falls towards atmospheric pressure and in turn the actuator on the distributor looses vacuum and cancels the retard.
On the later style with 062/067 distributors, the vacuum port on the throttle body is further back and in essence is connected to manifold vacuum. The vacuum switching valve and speed relay control the vacuum to the distributor. There is no tip in retard cancel on this system.

[MikeSimon]

(I had the same issue on my 1970 280 SEL, M130 motor with a non-working emission reduction system)

Dirk: Would you mind checking the casting markings on your cylinder head and let me know what they are? I am still trying to find background for the original head on my 280SL, which says 280SEL/SL on it and has number 130 016 17 01 and has a 9.0 compression. It is not in the list of W113 heads in the Tech manual and nobody seems to know anything about it.
You can use my e-mail mike.simon70@yahoo.com to spare the community from this.

[dirkbalter]

Dirk: Would you mind checking the casting markings on your cylinder head and let me know what they are? I am still trying to find background for the original head on my 280SL, which says 280SEL/SL on it and has number 130 016 17 01 and has a 9.0 compression. It is not in the list of W113 heads in the Tech manual and nobody seems to know anything about it.
You can use my e-mail mike.simon70@yahoo.com to spare the community from this.

Sure, check your mail.
Dirk

[bracurrie]

Bracurrie
I did just what you are suggesting using an 051 with a Pertronix igniter.  If your car has the vacuum idle compensator you can tee in the vacuum line there.   Use initial timing specs from a 68 or 69 model.  save your 061 as they are SL only and quite valuable to those of us who had them removed at some point.

I believe you mean the 062. The 061 is sedan use. According to the service manual.

[bracurrie]

Just a note on the 123 and later cars with emissions (70-71). If you are going down that road, spend the extra money and purchase the “123-Tune” with bluetooth. It has the ability to set an RPM trigger point to start the vacuum advance/cancel retard. You can set it anywhere you want such as where the existing system triggered at 2200rpm. It also has the ability to create your own timing map which is different than the older cars, hence why some have trouble with getting the older version of the 123 to work on emission cars with switchgear and the later throttle body.

Given that in my case the retardation is only for emissions my thought is that since no retardation is needed no trigger at 2200 RPM is needed. While technically not part of the distributor, I wonder should the emissions control measure of injection pump fuel shutoff (activates when throttle is at idle and transmission is in 3rd or 4th gear with clutch engaged) which doesn't impact drivability or performance should be preserved. Brad

[Tyler S]

Brad, you would still need to set a trigger point in the 123 software so that timing advances when you are off of idle. Since the throttle body does not have ported vacuum like other cars, advance would always occur without the trigger point. I would probably set it at no less than 1500 rpm in order to maintain a smooth transition back to idle while in gear.
As far as the fuel cut solenoid. I was told by another member that has worked on these pumps that the fuel cut actuations put extra stress on the internal linkages of the pump and there is the potential of these linkages failing over time.

[bracurrie]

Brad, you would still need to set a trigger point in the 123 software so that timing advances when you are off of idle. Since the throttle body does not have ported vacuum like other cars, advance would always occur without the trigger point. I would probably set it at no less than 1500 rpm in order to maintain a smooth transition back to idle while in gear.

Tyler, Thanks for your reply. In my 1970 US version the vacuum regulates retardation. Its primarily used for emissions, but I understand its also used to regulate idle for automatics. Since mine is a manual that isn't a concern. for a 123 distributor I believe I would use the mechanical curve right out of the service manual that mimics the 051 or 061 dizzy.  The only concern here would be what idle speed would be ideal given that there won't be a retard cancellation in use for cold or hot starts. I would go through the iterative idle setting procedure because without the retardation she idles too high. I was thinking 700-900 RPM.  Brad

[Tyler S]

Yes you could get away with no vacuum connection but you would want to add in what is lost on top of the original curve. So technically you would build a curve that starts at whatever advance btdc number from zero. Then create your curve to end at the full advance spec.
Also the 123 tune+ has a provision for adding advance during cranking @500 rpm. The curves for my 250sl are below.  I had created a curve for another members late 280sl. Ill see if I can find the post.
EDIT: Here is the post. https://www.sl113.org/forums/index.php?topic=23210.msg214545#msg214545

[bracurrie]

Yes you could get away with no vacuum connection but you would want to add in what is lost on top of the original curve.

Tyler, Thank you. I thought there was nothing lost "on top" as the retard is always canceled above 2400 RPM.
I really should learn more about engine performance tuning. In other words learn about how advance helps starting but not idle.
Is the 051 curve the most desirable?
Brad

[Tyler S]

I dont think there is any one curve that is best. But the 051 distributor and early throttle body is the easiest to work with. One vacuum line from the throttle body to the distributor and thats it. Remember that these are antiquated mechanical systems. The curves are linear sloping and are not really curves at all. Changing the curve on the original distributors is time consuming and requires special tools. Each engine has its own characteristics so some experimentation to see what works best is needed. Yes the retard is cancelled at 2400 rpm so in effect the timing is “advancing”. Having some advance above 0 BTDC does produce a smoother idle. One of the main reasons to retard the timing during decel was to ensure complete combustion and lower combustion chamber temps which lowers NOx emissions. The 051 system only did this when the throttle was closed. The fuel cut solenoid also accomplished this but some cars (late 250, early 280) had both retard when throttle closed and fuel cut systems during the transition to the late 280 system.

[jeffc280sl]

my post below was from a related topic.  it describes the emissions subsystems.  the ignition changeover concerns distributor and i thought it might be appropriate to add here

i believe the ignition changeover subsystem reduces emissions when the engine is cold, less than 17C or when very warm, over 100C by adjusting timing.    the second subsystem is basically an on/off switch for the fuel shutoff solenoid.  it gets inputs from engine sensors to include rpm and transmission pressure to indicate a deceleration mode and charges the solenoid.  fuel cutoff reduces the release of unspent fuel during this mode. a failure mode in this subsystem will be evident in an intermittent, on or off state of the fuel cutoff.  the operation of the subsystem can be eliminated by disconnecting the solenoid.

the ignition changeover subsystem can be checked using the procedure below.  you can compare the wiring diagram below and the one in my last post to see these two operations

[bracurrie]

Its enlightening to learn that with the 123 it’s possible to improve performance AND drivability on an engine where other mods are either difficult or expensive or both.

[jeffc280sl]

Very true.  Years ago I played in this area and bought an after market rpm switch.  See pic below.  Didn't really help as I recall and you can see what it looks like.  Ended up with 123 ignition and all has been good.  Looks better as far as mods go also

[Shvegel]

bracurrie,
You are correct.  062 is SL  and 061 is sedan.  Only difference is weights and springs and about $300 in the price tag of a used one.

[bracurrie]

bracurrie,
You are correct.  062 is SL  and 061 is sedan.  Only difference is weights and springs and about $300 in the price tag of a used one.

Yet the BBB Service Manual advance graphs lump the 061, 066 and 062 together has being identical.

[bracurrie]

Just an update after getting my vintage advisor and tech to check and set distributor timing. We were floored to find that at idle WO vacuum the car was set at 5 degrees AFTER TDC. Moving it to 8 degrees BEFORE TDC increased idle to over 1000 RPM and made the car run MUCH better. We also confirmed that above 2500 RPM the advance was just over 30 degrees.  I am leaving the retard system disconnected for now and as soon as the fuel supply problem is corrected I will reset idle to 700 RPM.
Some might ask how the timing got set to 5 degrees AFTER TDC. I had an oil service done by a shop that has some vintage experiance.  They commented that idle was too high so they corrected that by changing the timing. Argh!!!
No going back there.

[Benz Dr.]

You can change idle speed by changing ignition timing on these older cars. While some of that is unavoidable, it's best done by triangulating timing, fuel, and air until you get the desired idle speed. Using only one of those three inputs isn't as good and may be why they did it that way. It was the easiest way to do it.