electronic ignition-some help needed

[n/a]

The beautiful weather here in Ohio this weekend lured me outside to pamper my 71 280sl.  I had been waiting all winter to install a Pertronix electronic ignition to replace the points in the distributor.  I also purchased the recommended ignition coil from Pertronix, the 40,000 volt, 3.0 ohm, high performance "Flame Thrower."  The installation was amazingly simple.  I could hardly hold back my excitement with anticipation of never having to mess with distributor points again.
The car started up fine and seemed to idle beautifully.  However, when I reved the engine, to my horror, it sounded like the ending to a fireworks display on the Forth of July, kinda like someone was shootin' at me with a machine gun.  I adjusted the ignition timing to 8 degrees ATDC as indicated in the Big Blue Service manual.  Nothing helped.
 
The ignition on my car is a little different from earlier 113's.  I have what is known as the "transistorized ignition," consisting of 2 series resistances ( a 0.4 ohm and a 0.6 ohm), a switchgear, and a Bosch blue colour coil.  (See page 15-20 in the Big Blue Service Book).  My distributor is the Bosch #0231 116 062.  This distributor was not on the Pertronix on-line chart, but the sales person felt that the Pertronix 1863 was the one for me.
 
When I installed the Pertronix, I connected the black wire from the ignitor to the negative terminal on the new "flame thrower" coil, and the red wire to the positive terminal.  I wired the positive terminal directly to the ignition switch wire, as recommended in the installation guide.
 
Anyone with experience in this area, please offer your thoughts!
 
Thanks,
Don
1971 280sl
"If you're not the lead dog, the view never changes."

[George Davis]

Don,

two WAGs:

On the 051 distributor, the bracket for the vacuum control rod has to be modified slightly to clear the Pertronix unit.  Don't know if the 062 is the same, but maybe the vacuum control is hanging up on the unit?

Second, there is an rpm-controlled relay that affects ignition timing (vacuum advance/retard) on your car.  If the Pertronix wiring eliminated the rpm signal to the relay, timing will be affected, although I'm not sure exactly which way.

Good luck!

George Davis
'69 280 SL Euro manual

[Tom]

I have the Pertronix with the 062 distributor.  Best I can recall, you have to attach the green wire (that once was connected to the transitor module) to the negative side of the coil to enable the RPM relay to pick-up the rpm signal.

Also, you likely know that you do not need the balast resistors with Pertronix.  If you are running your power source through the resitors, that will be a problem.

Oh, one more thing...you will need a hotter coil than the standard coil.  If you need a reference on the coil I have, let me know.

Best,

Tom

____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[jeffc280sl]

I have the 010 aluminum distributor with the Crane ignition system.  Picking up on what the other guys said there should be a wire connecting pin 4 of the speed relay to pin one on the coil. I believe the wire is green/black in color. The speed relay receives rpm data from the coil and at 2400 rpms it energizes the two way valve which provides atmospheric pressure to the distributor which I think eliminates the retard.  At 2200 rpms the speed relay removes power from the two way valve and vacuum is again applied to the distributor.

With the Crane unit pin one on the coil also gets an input from their ignition module and pin 15 on the coil gets an input from the .6 ohm resistor.

Jeff C.
1970 280SL 4-speed

[n/a]

I saw the on-line information that Randy Durrance put together on the Pertronix.  I had anticipated that I would need to modify the interior bracket.  However, I discovered that this was not necessary for my distributor.  I hadn't thought about the speed relay.
Thanks!

On the 051 distributor, the bracket for the vacuum control rod has to be modified slightly to clear the Pertronix unit.  Don't know if the 062 is the same, but maybe the vacuum control is hanging up on the unit?

Second, there is an rpm-controlled relay that affects ignition timing (vacuum advance/retard) on your car.  If the Pertronix wiring eliminated the rpm signal to the relay, timing will be affected, although I'm not sure exactly which way.

Good luck!

George Davis
'69 280 SL Euro manual
[/quote]

[n/a]

Many thanks to Tom (and others!) who are helping with this issue.
I looked for info on the speed relay, and, sure enough, as Jeff described, on page 00-78/3 of the service manual it shows wire going from pin 4 on the speed relay to terminal 1 on the coil.  I don't recall seeing that wiring for my car.
Tom,
Please describe in more detail what you are saying about a green wire that was once connected a "transitor module."  What is the transistor module that you are referring to.  I think you are onto my problem.  I need to find that wire.
Thanks,
Don

quote:Originally posted by Tom

I have the Pertronix with the 062 distributor.  Best I can recall, you have to attach the green wire (that once was connected to the transitor module) to the negative side of the coil to enable the RPM relay to pick-up the rpm signal.

Also, you likely know that you do not need the balast resistors with Pertronix.  If you are running your power source through the resitors, that will be a problem.

Oh, one more thing...you will need a hotter coil than the standard coil.  If you need a reference on the coil I have, let me know.

Best,

Tom

____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[n/a]

Tom,
One more thing.  What specs did you use for the ignition timing?  According to the way I interpret the chart for 1970 and 71 280sl, it should be set at 8 degrees ATDC (to the left of the zero when viewing the car from the front) at 800 rpm (idle speed).

I did purchase the high performance coil recommended by Pertronix.

Thanks again,
Don

[Tom]

Don,

This is from memory, but the wiring harness has several connections to a bakelite electrical terminal block that is located in close proximity to the transistorized unit, which is attached to the underneath of the battery tray.

Note the green wire in the attached pictures of that same bakelite terminal block as well as the green wire coming from the harness.

For ignition timing, focus on setting the timing at appx 30 degrees BTDC at 3000 rpm, with the car warm, vacuum line attached to the distributor vacuum box, and the rpm feed (green wire) attached to the negative terminal of the coil.  You will note that if the RPM relay is picking up the rpm feed that the two way switch will kick in at about 2400 rpm and release the retard and advance your timing.  If you don't see a sudden advance in timing around 2400 rpm, something is not working correctly.  Of course, in setting timing, ensure your linkages are adjusted, fresh plugs, etc. before setting timing.  Timing at idle should be at about 0-5 degrees before TDC once the timing at 3000 rpm is set correctly.

Best,

Tom



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____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[n/a]

Thanks Tom.  It looks like this is the terminal where the condenser wire attaches.  Sound right?
Really appreciate the help.
Best regards,
Don


This is from memory, but the wiring harness has several connections to a bakelite electrical terminal block that is located in close proximity to the transistorized unit, which is attached to the underneath of the battery tray.

[n/a]

Tom,
The Pertronix part they sent me was 1863.  Is this the same part number that you have for your 062 distributor?
I would like to be certain that I am working with the correct unit for my car.  Also, have you ever measured the dwell after installing the pertronix.  I believe it should be 29-31 degrees.  
Thanks,
Don

[Tom]

Don,

Don't recall the model number of Pertronix that I have.  Is this on the Ignitor?  I will check tomorrow.

My dwell is 38 degrees and never changes.

My Pertronix was installed by Randy Durrance at the same time he re-built my distributor, and I recall he had to grind down the bracket to get it to fit the distributor.

Did you re-install the small screw on the side of the distributor that use to hold the condenser?  If you did, remove it, as without the space taken by the condenser bracket, the screw will make contact with movement inside the distributor and possibly damage the springs.

Don't give up on the Pertronix unit-it works great once you get it right.

Best,

Tom


____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[Benz Dr.]

Not quite. The car has to be in gear and at road speed before it will switch over at 2400 RPM. So many people make that mistake and think the distributor switch gear isn't working. I believe there's also an oil temp and coolant temp input that can affect the switch over. A simple test is to undo the plug on the two way valve and drive the car and see how it runs ( which won't be impressive)and then plug it back in and compare. It should pull well up to higher RPM 's in all gears.

Dan c

Daniel G Caron

[Tom]

With a timing light, with my head under the hood and the car *in park*, I can actually observe my retard going away and advance kicking in at 2400 rpm.  The car (at least my car) does not have to be in gear and on the road.  And I have an automatic, which could  make a difference.

Otherwise, how would one set the timing other than at idle?  Also, the book gives a spec for timing at 3000 rpm and doesn't indicate in the book that it has to be done on a dyno or at speed.

Best,

Tom

____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[Naj ✝︎]

Hi Tom (and others with Pertronics)
There have been some comments that there is a misfire (flat spot??) around 4000/4500 rpm with the Pertronix system installed. I certainly had quite a bit of trouble with my original unit, which was then replaced but it is still there but to a lesser degree.
Anybody else notice this??

naj

65 230SL
68 280SL

[Tom]

Naj,

I have not noted the flat spot you mentioned.  I think the Pertronix works pretty well, and I actually had a Crane system in that I switched out for the Pertronix.  Crane worked well, but I just wanted to tinker (running out of projects) so I put the Pertronix in.

Best,

Tom

____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[n/a]

Hey Tom,
Any time you feel the urge to tinker, and you'd like to visit Cleveland--be my guest.  I got this benzino in the garage that just loves to be tinkered with.  


  Crane worked well, but I just wanted to tinker (running out of projects) so I put the Pertronix in.

[Benz Dr.]

I'm going to look at this again but I was under the impression that an oil pressure switch on the auto trans needs to be on for the switch gear to work. Normally I put a test light on the switch over valve and tape it to the windshield. I've not been able to make them switch anyother way other than during driving.

You could be right though.

Dan c

Daniel G Caron

[hands_aus]

Hey Tom or anybody with the knowledge,

With the Pertronix unit, is it important to have the correct Dwell angle?

I ask because I have just installed a Pertronix unit (1864LA for 051 distributor) in my car BUT the Dwell angle shows at 33.5 degrees not 38 degrees as per specs.
I am having trouble getting the timing correct in my 250 SL, is it possible that is the cause?

Bob (Brisbane,Australia)
early 250 SL, RHD

[Naj ✝︎]

Bob,
You cannot adjust the dwell angle in an electronic system. The processor does that??
Should be able to time correctly though.I had to file a notch in the mounting plate (where there is a little bent over tang - on the lower plate to keep upper plate in place) to get the sensor to mount properly.
I believe the 1864LA is the correct mounting plate for the 051.
Please let me know if you get smooth operation thru the rev range once the timing is correctly set.
naj

65 230SL
68 280SL

[Tom]

Bob,

Puzzling to me why you can't get 38 degrees dwell-should get that out of the box.

Dan, I have another 71 280sl that is an automatic and fairly original.  I will put a timing light on it as well and see if I get the same advance at 2400 rpm as I do on my driver.

Best,

Tom


____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[Cees Klumper]

I have an electronic ignition unit made in the UK (by Newtronic) that has performed flawlessly from the get-go. No flat spots etc. I must say I have not measured the dwell angle, but here's the point: on my unit, there is an optical pick-up that is triggered by a plastic disc that is rotating in the distributor (slips onto the shaft) and it has six slits in it. I have always assumed that the width of these slits determines the dwell angle (that is, I have also assumed that dwell angle means the length of time / number of degrees that the signal is transmitted). Point being that the dwell angle, if I am correct, on my unit is 'mechanical' rather than 'electronic/programmed'. Am I wrong? And do Pertronix units work differently?

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[hands_aus]

Naj,
Given that there is no adjustment for dwell on the 1864la unit, I figured it should be set for the correct dwell angle of 38 degrees.
I will keep you informed of my progress.

Tom, I thought it should be 38 degrees out of the Box too.
Pertronix do not recommend removing the resistors on all systems. They say to keep it if it is in the circuit all the time like for my 250SL. This is different from the 280SL with two resistors.

Don, there is a Freqently Asked Questions page on the Pertronix site worth reading.
It tells you how to work out if your voltage and resistance are correct. Yours should be spot on with the new coil.

My understanding is that the MB electronic unit REDUCES the current through the Points which extends their life.

So I have another question,

Does the Pertronix unit REPLACE the MB electronic unit in the 280 SLs OR does the MB unit provide other features too?

Maybe Don can remove/disconnect the MB electronic unit.

Bob (Brisbane,Australia)
early 250 SL, RHD

[Tom]

Bob,

The Pertronix unit obsoletes the transistorized ignition module that is under your battery tray.  You can remove it if you like.  

Best,

Tom


____________________________________

1971 280sl Tunis Beige Metallic
1971 280sl Tobacco Brown
1994 E320 Cabriolet, Smoke Silver
1999 E320 Wagon 4 matic, Brilliant Silver
____________________________________

[n/a]

Thanks to everyone who tried to help with the Pertronix setup on my 71 280sl.  However, it seems that the results have gone from bad to worse.  The initial symptoms were that the car started and idled fine, but backfired violently when the engine was reved.  Later on, it started idling very rough, and it was difficult to keep it from stalling out.  Now, I can't get it to start up at all.  I am getting some spark (according to my timing light).  However, it cranks and cranks, with an intermittent putter.  Plugs become wet with petrol.  I needed to recharge the battery 3 times due to energy loss from cranking.  
I don't know if the source of the problems is related to the tinkering around, a faulty Pertronix unit, or an incorrect Pertronix unit.  As mentioned before, my Bosch distributor 062 is not listed on the Pertronix on-line list.  The sales person recommended Pertronix part #1863 for my car.  I also installed the recommended Pertronix high performance coil.  I wired the coil directly from the ignition switch, as recommended in the literature.  I by-passed the MB "transistorized" ignition parts.
At this point, I'm pretty close to giving up with Pertronix.  I'll check their on-line FAQS to see if I can learn anything new.  I plan on calling Pertronix to see if I can try another unit, since I have heard reports of faulty units.
If none of this works, I guess I'm left with exploring Crane or going back to (aaargh) those mechanical points.
Best regards,
Don

[n/a]

I also just installed the electronic unit in a 64’ 230sl with the later 250 motor in it for a friend of mine. It was a little tricky at first but I found the problem and now it runs GREAT!!! When I first installed the small little ring on the distributor shaft I did not notice that it was hitting the small bracket for the vacuum advance. This interference was very minimal and only caused the ring to sit slightly higher on the shaft. The car would run like this but I could not get the timing straight. It would pop and miss differently each time I ran the motor. After grinding the little bracket on the vacuum advance and getting the ring to fit properly the motor ran like a champ. I did however have to make a large adjustment to the ignition timing but that was it. This is a great little unit and a wonderful upgrade on our ignition systems. (No flat spots in the RPM curve and much better throttle response.)
 I don’t know if this is going to help you but it dose sound like your symptoms are the same.


Jerry P.