Points, setting of --

[TheEngineer]

I need help with setting the points: On a 0 231 116 051 distributor I am using a Micronta Dwell Meter. It has a three-position switch for: Dwell, Tachometer & Points. I’m reading on the 6- cyl. Scale. The meter is connected with the black wire to ground and the red wire to coil neg. (the green wire which goes to the distributor). I started out by setting the gap to .030 mm. The dwell angle read 36º. I decreased the point gap and the dwell angle now reads 38º. I left it at that. Car runs pretty good. But my meter, with the switch at the “points” setting, still shows the points not in the green range (marked “Good”) but about straight up, in the white range. The old points showed about the same, that’s why I replaced them. I’m doing this reading with the engine running. I have no instructions for this meter; I’m flying blind. With the switch at the “Tachometer” setting, the meter reading correlates satisfactorily with the on-board tachometer. Also, when I speed-up the engine the indicated dwell angle decreases substantially. How about some guidance, please.

1969 280SL,Signal Red,  Retired engineer, West- Seattle, WA

[A Dalton]

Point test on dwell meter is a Resistance test.
 You can not test point resistance with a running engine.
 It is tested as one would test any resistance circuit...ie- with points in full closed position.
 If dwell decreases alot, you have a worn dist.
 The dwell is set fine , so I think you mean you have the gap set at .3mm [calls for .3-.4]  - .030 would be approx .001"

[Tom]

Arthur,

I am trying to measure dwell on a 280sl (70) with transistorized ignition.  How do I get the tach pickup on this set-up?  Also, can you fill in some of the details on how to measure dwell to verify the initial manual settings?  thanks


1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
1970 280sl Deep Red (Project Car)

[TheEngineer]

Arthur:
Why is it that things go so much better with instructions? The engine must be not running, ignition must be on, points must be closed. It is better to pull the fuse for the fuel pump. And-----: It is better to remove that wrench with the 27 mm socket from the front of the engine: you know, the one I just used to turn the engine over to close the points? It is a really quick way to loosen that bolt.
And: You are right: Decimal point in the wrong place: Should read: .3 mm. A common engineering error.
1969 280SL,Signal Red,  Retired engineer, West- Seattle, WA

[A Dalton]

Eng,
 A little trick I use to check the condition of the points when using the POINTS setting on a dwell meter is :
  Set the meter up and then make sure the points are completely closed  [ the actuating block should be off the dist. cam, assuring points have  full closed spring tension.. this is easy if you just have the block perpedicular to a flat face of the cam].
 Now , you take your resistance reading at the meter ..Next, you take a little stiff copper wire and jumper across the two stainless arms that hold the point contacts.. this shorts out the points [ I just use the end of a  screwdriver blade] ... if the meter reads the same , you know you have good conductivity at the point surfaces... but, if the reading is higher when you remove the jumper, your points have resistance and have poor conductivity...time for  new ones..
 This same test can be done without turning on the key if you just use a simple ohm meter across the point feed wire and ground and make the same 2 comparisons...
 Get that socket off the crank and use that remote starter circuit you have installed....

[A Dalton]

Tom

 It has been years since I worked on transistor ign of the later 113s, but I do have that info here in my notes ..
 I do remember going through this exact question and having found a simple answer
 I will get to it and post finding.

[n/a]

I know that much of the enjoyment we get with these cars is the process of running little gauntlets like properly setting an old points system to perfection.  However, if you do happen to get tired of this exercise and would like to move on to bigger things you can buy an electronic/hall-effect system from Pertronix and never have to do it again.

I did mine about a month ago on two of exactly the same distributor you have and couldn't be happier. My 66 230 SL and 69 280 SE are now both running with a Pertronix instead of points. The Pertronix model for your distributor is 1864-LA. No points, no dwell, no condensor, completely reversable,joyously consistent and more powerful.  

While I was doing the Pertronix conversion I completely gutted the distributors, cleaned and oiled every piece and repainted them both. It was probably as much fun as you are having now

Mikey

[TheEngineer]

Mikey:
Obviously you can read my mind or,perhaps, GREAT MINDS think alike: I have just been investigating the Pertronixs Ignitor ignition and wanted to post an inquiry on the forum. Thank you for your input! When I measure dwell, I get 40º at idle (750RPM) and 34º at 3000 RPM. The book says it should not change more than 3º. A.Dalton says: It indicates wear of the distributor. After only 36 years? I'm twice as old and not worn out yet. Well - maybe I sleep in longer (and fall asleep on the couch)

[n/a]

I'm very pleased that you had the same idea about Pertronix, it's a good one. Although I keep all the old parts in the glovebox (just in case) I drive my 280 SE 100 miles each day with no problems.

It should be easy for you to address the worn bushings while you have the distributor removed to install the Pertronix. I just don't know what the part numbers are for the bushings or any other parts. Maybe someone on the forum can help.

Does anyone know of a Kit or a list of part numbers to fully rebuild the 051 distributor?

Mikey

[TheEngineer]

Mikey:
Let's talk about the "bushings": Have you pulled the shaft in the distributor and verified that there are bushings? Do I have to press out the pin in the bottom of the shaft which holds the drive dog? If I were to design a cheap distributor, I'd go to an aluminum housing and would run the steel shaft in the aluminum and not need bushings. That would save 50¢. So, are there bushings in the 009 distributor? I called Bosch and they do not supply rebuild kits other than points, condenser, cap & rotor. I can get OilLite bushings, but maybe not metric ones to fit. I also found a website about tweaking distributors:<http://members.aol.com/dvandrews/timing.htm>
I called my friendly supplier: My 009 distributor takes a 1867 Ignitor module or a 91867 Ignitor II module which is also used in Porsche 911 & 911S I found that the 009 distributor doesn't have enough vacuum retard + centrifugal advance to get me 3ºATDC to 30ºBTDC. On the 051 distributor I could lenghten the vacuum retard to get me there, but on the 009 I can't. I'd have to bend the stops for the centrifugal advance. Has anybody been down that road :?:

[Cees Klumper]

Dan Caron (Dr. Benz) can supply a complete rebuild kit (including the bushings - I'm not sure whether they are in the alumninum body distributors).

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[n/a]

quote:Originally posted by theengineer

Mikey:
Let's talk about the "bushings": Have you pulled the shaft in the distributor and verified that there are bushings? Do I have to press out the pin in the bottom of the shaft which holds the drive dog? If I were to design a cheap distributor, I'd go to an aluminum housing and would run the steel shaft in the aluminum and not need bushings. That would save 50¢. So, are there bushings in the 009 distributor? I called Bosch and they do not supply rebuild kits other than points, condenser, cap & rotor. I can get OilLite bushings, but maybe not metric ones to fit. I also found a website about tweaking distributors:<http://members.aol.com/dvandrews/timing.htm>
I called my friendly supplier: My 009 distributor takes a 1867 Ignitor module or a 91867 Ignitor II module which is also used in Porsche 911 & 911S I found that the 009 distributor doesn't have enough vacuum retard + centrifugal advance to get me 3ºATDC to 30ºBTDC. On the 051 distributor I could lenghten the vacuum retard to get me there, but on the 009 I can't. I'd have to bend the stops for the centrifugal advance. Has anybody been down that road :?:

Mikey

[n/a]

Yes, there absolutely were bushings in the shafts of both of my 051 distributors and yes you do have to press out the pin at the bottom of the shaft to get a look. Both of my units also had a felt-like material adjacent to the bushing, I assume to block the engine oil from coming up or to wick the oil down from the oil service port that is on the side of the distributor body.

I don't know anything about the 009's but I bet Dr Benz can help you there.

quote:Originally posted by Mikey

quote:Originally posted by theengineer

Mikey:
Let's talk about the "bushings": Have you pulled the shaft in the distributor and verified that there are bushings? Do I have to press out the pin in the bottom of the shaft which holds the drive dog? If I were to design a cheap distributor, I'd go to an aluminum housing and would run the steel shaft in the aluminum and not need bushings. That would save 50¢. So, are there bushings in the 009 distributor? I called Bosch and they do not supply rebuild kits other than points, condenser, cap & rotor. I can get OilLite bushings, but maybe not metric ones to fit. I also found a website about tweaking distributors:<http://members.aol.com/dvandrews/timing.htm>
I called my friendly supplier: My 009 distributor takes a 1867 Ignitor module or a 91867 Ignitor II module which is also used in Porsche 911 & 911S I found that the 009 distributor doesn't have enough vacuum retard + centrifugal advance to get me 3ºATDC to 30ºBTDC. On the 051 distributor I could lenghten the vacuum retard to get me there, but on the 009 I can't. I'd have to bend the stops for the centrifugal advance. Has anybody been down that road :?:

Mikey

Mikey

[Benz Dr.]

You guys want me to tell you ALL of my secrets? You won't need me any more after I do ~)

 The pin on the bottom of the shaft can be hard to remove as it's pressed in and all the parts are hardened steel. I always mark the shaft and drive collar before removal so I get it back on in the right position.
The bushings are made out of a self lubricating material but the originals are steel or some sort of alloy. I believe all distributors have bushings installed. There is a felt wick inside of the housing which doesn't come with a rebuild kit. You have to remove this wick material BEFORE you drive out the bushings if they need replacement. If the bushings are tight I leave them installed as new ones won't make any real difference. I look at the top of the shaft which should be smooth and have little or no scoring - this where a lot of radial play happens. I also look at the radial play between the shaft and the points cam. If this area received little or no lubrication it will wear out and can be quite loose. The points cam must be replaced if it's loose.
There are also a number of small shims which need to be installed and they're installed in a certain way. Too tight or too loose will cause operating problems.
The mechanical advance can be changed as far as how quickly it responds and at what RPM it starts at but this is fairly limited. The actual advance curve is determined by the size of the flyweights which can be changed for a customized operation.
The total amount of mechanical advance is limited and can't be changed very much without radical grinding.

Daniel G Caron

[TheEngineer]

Thank you, Dr. Benz: I was just wondering when you'd come on board. On this 051 distributor, which I got from the junk yard, I had to turn the drive dog 180° to get the same rotor position as the 009 distributor which came with the car. To do that, I had to remove the pin. But I didn't look at the bushings, because I didn't pull the shaft out. Now that distributor is in the car and it is easier to ask you, instead to removing it again. But as you can tell from the wandering dwell angle, the cam is doing an "orbit". I know that you prefer points, but it may be interesting to install a Crane unit, just to see if it makes any difference. It appears that the installation is reversible. From what I can find out, the crane is sort of "universal"; and I could install it in the 009 distributor as well. Also, it appears to be less sensitive to play in the distributor shaft. With Pertronix I'd have to buy two different modules. And thank you, for your observation, that the felt wick still needs oiling. With no points there, one may not look at the distributor again ever. And, yes, I'd like to know all your secrets, please. And we'd still need you! I did the Pertronix thing; please read about it under "Comments please on PERTRONIX IGNITOR"