Bosch distributor 009 ?

[merrill]

so, still trying to dial in my 66 230 sl auto.  

I have a bosch 009 vacuum retard at idle distro.
When setting the timing per the book this distro should be at +/- 2 btdc  deg at 850 rpm.

so, I set my timing at about 2 deg btdc at idle.
Per the book the timing should go to 30 deg atdc at 3000 rpm.
my timing NEVER gets to 30 deg.  I get to 27 or so.

The vacuum retard system on my distro does not leak. checked with mity vac tester.  (all lines etc are good )

I recall the vacuum retard system is adjustable.  
would I be able to adjust the vacuum retard to (I gues ) increase the range?
I need to have 2 deg btdc at idle and 30 atdc at 3000 rpm  currently
I am at        2 deg btdc at idle and 27 atdc at 3000 rpm

thoughts?

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[Longtooth]

Matt, my BBB Job No. 00-7 Ignition timing, Revised Apr '67 says ignition timing must be done (strobed) with vacuum line disconnected from the distributor.

Sounds like you may be getting the 3k rpm value (27 degr ATDC) with vacuum control attached instead of without it attached as per spec for 3k (and all other rpm's) ... 30 degr ATDC.  I assume you've set dwell angle at 38 degr (+3 degr / - 1 degr) before you measured dynamic timing at rpm's).

I don't see an ... Bosch ...009 distributor in the book though (for any version of the 230SL or 250SL), so I may be misunderstanding your dilemna.  The one's listed in the distributor timing tables are VJUR 6BR 49T, IFUR 6 0-231-116-046... 047... 050... and 051.   The ...49T and all the other IFUR distributors are listed for the 230SL's engine... the 250SL lists only the ...047 & ...051 distributors.

The stobe timing values for various rpm are listed without vacuum... and the idle is at 800 rpm (table listed idle value) which should have no vacuum being applied at that rpm.  All other timing values are without vacuum.

The timing differs depending on whether it's statically timed (basic set-up conditions), or dynamically (strobe) timed.

For basic set-up the static timing light check is 2 degr BTDC for the ...49T distr... 6 degr BTDC for the ..046 & ..050, 3 deg BTDC for the ..047, and 6 degr BTDC for the ..051.   I used to time my VW's and friends Porsches only statically... a timing light (continuity light), feeler gauge, and a screwdriver, and a 19mm Socket to turn the engine back and forth.  I may have used a dwell meter later when I got more "sophisticated"... and even later I used a strobe... really "high tech" (for me in those days).  I'd test my totally static setting under no load at idle and over a range of rpm's by listening to the engine, then follow-up with a road test under load.  I got so that I could find the "perfect" timing for each car after a couple of trials.  Later, when I began using a dwell meter and eventually a strobe, I could tweek it in less time, but the timing was the same whether I did it totaly static or used the dwell meter and strobe.  Of course these were 4 cylinder, very forgiving engines --- even the Porsche's (356's).  I found the most important part of a tune-up was making sure the valve clearances were right before anything else. Parenthetically, I learned how to time VW's and Porsches statically from an authorized VW / Porsche engine mechanic who was totally blind!!!! I mean couldn't see nothing at all.  It was all be feel and sound (and smell... he used his nose to check exhaust gases for fuel/air mixture checks).  His timing light was actually a buzzer instead of a light.  I'm not lying.  He could tear-down and rebuild a VW engine as well or better than the mechanics that could see... a little slower, but he never had to take anything back apart to correct a mistake.... so his net time wasn't any different than the others.    

Back to the W113's ---
For set-up strobe check at starter cranking speed, the values increase by 2 degr for all distr. versions.... i.e. the 6 degr BTDC value becomes 8 degr BTDC (with spark plugs installed) at starter cranking speed, etc.  The corresponding dwell angle, at idle speed (800 rpm) is 38 degr (+3 degr/- 1 degr) for all distributor versions on the W113's.

For dynamic strobe timing, under no load at engine speeds the values are:
800 rpm:
  4-7 deg BTDC ... 49T distr.
  8 degr BTDC ... 046 & ..050 distr.
  2 degr +2 deg/-0 ATDC (2 - 4 degr ATDC... for all other distr. versions.  

1500 rpm (without vacuum control):
  15 - 19 degr  ... 49T distr.
  10 - 12 degr  ... 046 & ..50 distr.
  13 - 20 degr  ... 047 distr.
  12 - 19 degr  ... 051 distr.
 
3000 & 4500 rpm (without vacuum control):
  30 degr (all W113 Bosch distributor versions)
 
Following is directly from the BBB:

The start of vacuum control should occur above 800 and before 1000 rpm under no load.

Measurement of the automatic vacuum control is done with no load, throttle valve completely closed, only at idling speed with control rod disengaged from the control shaft to the reversing lever on the intake manifold.  Ignition setting should be retarded (2 degr, +2 degr/ - 0 degr)ATDC.  To adjust the vacuum control range, the total adjustment range can be increased by backing off the stop nut on the pull rod that connects the diaphragm in the vacuum box with the distributor plate, and the range can be decreased by screwing the stop nut in.

Longtooth
67 250SL US #113-043-10-002163
The 6% Club - Best of the Best
'02 SL500 Sport

[merrill]

longtooth,
thanks for the reply

the 009 is the replacement for the 051.  vacuum retard at idle.

after about 1000 rpm there is no vacuum at the throttle body so I have just been setting the idue with the vacuum connected.

I guess I will set the timing to 30 deg atec at 3000 with vacuum connected and see what happens.

thanks
matt

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[Naj ✝︎]

quote:I guess I will set the timing to 30 deg atec at 3000 with vacuum connected and see what happens.

Try 30 degrees btdc @ 3000 rpm

naj

68 280SL

[merrill]

Naj,
oops, thanks for the ATDC VS BTDC correction

I just returned from doing some testing

The timing setting per mb should be  
idle (850) rpm  2 deg ATDC +/- 2 with vacuum attached
1500 rpm 12 - 19 deg btdc
3000 rpm 30 deg btdc
 
I tested the unit today with the following restults
idle   2 deg Atdc at 850 rpm  with  vac,  8 deg BTDC with out vac
1500  11 deg Btdc  with vacuum ,   9 deg BTDC with out vac
I reached 30 deg BTCD at 2300 - 2400 rpm not 3000 rpm.
 
It seems like the distro is reaching 30 deg Btdc too soon and the vacuum retard is too short.
I think it is supposed to have a range of 14 deg +/- 3 deg and I have about 10 deg range.
I have a slight pinging under acceleration.
I checked the vacuum line from the throttle body with a mighty vac.  I did not have any leaks.

thoughts?


Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[Longtooth]

Merrill, you said in your most recent post "I have a slight pinging under acceleration."

And in your other post you stated at idle 850 rpm "8 deg BTDC with out vac
1500 11 deg Btdc with vacuum , 9 deg BTDC with out vac. I reached 30 deg BTCD at 2300 - 2400 rpm not 3000 rpm."

All the following is discussed based on without vacuum timing.
 
Your data makes more sense IF your stated 8 degr BTDC at idle (850 rpm) were in fact 8 degr ATDC. Are you sure you're reading it right?  The difference between idle (850 rpm) and 1500 rpm by your measures is only 1 degree, whereas the spec's without vacuum should have a 14-15 degr. difference.  IF your idle value were in fact 8 degr ATDC then the difference between idle and 1500 rpm is 17 degr.  Furthermore, your pinging condition would also make sense since the pinging occurs when the sparks too far advanced.  If your idle timing is actually 8 degr BTDC, then both your idle and 1500 rpm timing are too advanced ... by 6 -7 degr.   This is also to say that your point gap is opening 6-7 degr too soon.  

Rotating the distributor in the direction which retards the spark --- so that the 1500 rpm timing is at 12 - 19 deg BTDC will also / should also shift your idle (850 rpm) spark to 1-2 degr ATDC.

If indeed your idle timing is at 8 degr BTDC and 1500 rpm's at 9 degr BTDC, then something's really wrong since the rate of change of points opening with increasing RPM is far too little... only 1 degr change over an increase in rpm of ~750. The points spring determine rate at which the points can close, which determines how fast the points can close when the distributor cam lobe lets them. The rate of closure times the static point gap distance determines the time it takes to close the points.  The time it takes to close the points at any given rpm will increase when the point gap is larger, and time it takes will decrease if the point gap is reduced.  

As the distributor cam rotating velocity increases, there's an increasing lag in time (based on the mass of the points and the point spring rate) between the point in time the cam lobe lets the points close and the time it takes for them to actually close... hence the closure occurs relatively later with increasing rpm.  The rate of change of point gap closure with increasing rpm from 800 to 1500 should be ~+2 to +2.6 degr per 100 rpm increase in engine speed. Your indicated point gap closure rate with increasing rpm is only 0.15 degr/100 increase in rpm!

On the other hand, IF your idle timing is actually at 8 degr ATDC (instead of 8 degr BTDC as you've stated) then the rate of closure with increasing rpm is +2.6 degr per 100 rpm.... basically right at the upper end of the spec. If the point gap were reduced a tad, the rate of change of closure timing with increasing rpm would decrease.

There are 2 possibilities I can think of...

1) If the actual timing at 850 rpm is as I've conjectured... 8 degr ATDC instead of 8 degr BTDC as you're stating... then your timing is too advanced by ~6 - 7 degrees at idle. If so, you need to rotate the distributor body until you're getting 2-4 degr ATDC at idle... (subtract 1 degree for every 50 rpm your idle is over 800 rpm... so at 850 rpm your setting should be 1-3 degrees ATDC).  

2) If the actual timing at idle (850 rpm) is as you've stated, then the points are closing far too fast at idle relative to their closure at 1500 rpm. If this is the case, then either your distributor body is rotating when you increase rpm to 1500 rpm after setting timing at 850 rpm, OR your point gap's far to small when you set them statically.  Use a dwell meter (use the 6 cyl. engine markings for dwell) to set your point gap so that the dwell is 38 (+3, -1 degr.) at engine cranking speed.  The static point gap (at TDC .... moveable point cam on top of distributor shaft cam lobe)should be in the range 0.3 - 0.4 mm (12 - 15 mils ==> 0.012 - 0.015 inches).  

For the time being, forget about the vacuum advance magnitudes.... get
1) point gap set right,
2) dwell angle set right at idle (800 rpm) without vacuum.
3) timing right at idle without vacuum (2- 4 deg ATDC at 800 rpm or 1-3 degr at 850 rpm).

When the above are correct, then check 1500 and 3k rpm timing ... all the above using a strobe. They should all be within the spec'ed allowances since they're without vacuum... before moving to the vacuum checks.  If the timing values aren't correct at 1500, 3k and 4.5k, then we'll need to work on what's wrong before moving on. By the way, there are no spec's for the timing values with vacuum applied.  

The BBB instructions for changing the vacuum range is described below.
From the BBB:
To adjust the vacuum control range, the total adjustment range can be increased by backing off the stop nut on the pull rod that connects the diaphragm in the vacuum box with the distributor plate, and the range can be decreased by screwing the stop nut in.

Here's the chart that shows spec'ed timing vs rpm, and 2 versions of your timing values... one with the values you reported, and one denoted "Merrill ?" where I've plotted the timing assuming your 850 rpm idle timing is actually at 8 degr ATDC instead of 8 degr BTDC as you reported it.



Longtooth
67 250SL US #113-043-10-002163
The 6% Club - Best of the Best
'02 SL500 Sport

[merrill]

longtooth

For the time being, forget about the vacuum advance magnitudes.... get
1) point gap set right - pint gap = 38 deg.which is about dead on.
2) dwell angle set right at idle (800 rpm) without vacuum. - not sure what this is
3) timing right at idle without vacuum (2- 4 deg ATDC at 800 rpm or 1-3 degr at 850 rpm). - AT idle without vacuum is 8 deg BTDC.

my  bbb has the 230 sl timing at idle at 2 deg Atdc +/- 2.  I assume this is with vacuum.

I suspect my distro is not working correctly.  I have send Dan a note to see if he can test / rebuild my distro.

thanks
matt

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[Longtooth]

Matt,
The point gap is a physical measure of distance between the point contacts with movable contact cam on the high point of the distributor shaft cam.  The high point of the distributor cam should be at #1 at TDC... i.e. with the pointer on the distributor pointing to the mark on the distributor body.  

Dwell (angle) is the rotation angle of the distributor between points opening.... i.e. degrees of rotation of the distributor shaft while points are closed.

"Dwell angle is a measure of the duration of time that the primary circuit of the ignition system is closed to energize the primary windings of the coil. It expressed (and measured) in degrees of rotation of the distributor rotor, hence the use of the term "angle".

In actual operation, as the distributor mechanism rotates, the points (or electronic module in electronic ignition systems) are closed for a certain number of degrees of rotation, and open between these points. Simply as a matter of interest, this means that the total number of degrees during which the points are closed, plus the total number of degrees that they are open, will equal 360 degrees."

If dwell angle is right then the point gap should also be correct.  I always set the point gap first, then measure dwell and make fine tune adjustment if necessary to the point gap to get dwell angle "right on".

Your idle (850 rpm) measure with a strobe light is way off as you've reported it... 8 degr BTDC when it should be 2-4 degr ATDC without vacuum.  What I don't understand however is why or what is preventing the distributor body from being rotated enough to move timing to 2-4 degr. ATDC (at 800 rpm... 1-3 degr ATDC at 850 rpm)  from your current 8 degr BTDC at idle... I'm also asking whether you're absolutely sure the idle (800 or 850 rpm) measure of timing is indeed 8 degr BTDC?... as opposed to ATDC.

You should be able to adjust the timing by rotating the distributor body to almost any desired magnitude of ATDC or BTDC at idle within a range where the engine doesn't start back-firing or coughing/sputtering and dying.

I get the impression (and please pardon my impression if it's wrong) that you're not rotating the distributor body to adjust the idle timing to the specified 2-4 degr ATDC.  My impression is based soley on the fact that you haven't mentioned any problems encountered by adjusting the timing (distributor body rotation) to a value other than the one you're reporting as consistantly being 8 degr BTDC.  What happens that you can't adjust it (rotating distributor body)  to 2-4 degr ATDC at 800 rpm (or 1-3 degr at 850 rpm)?... ALL without Vacuum control.

As shown in the chart I plotted for the spec'ed and your reported timing values, the slope of the line for your reported timing values (timing vs rpm) from idle to 1500 rpm is way, way, way out of line, far to little change in timing from idle to 1500, but the slope from 1500 to 2400 or so is approx. within the range of expectations.

However, as I also conjectured in the chart, if I exchange your timing value at 8 degr at idle from BTDC to ATDC then the slope of your distributor's timing is very nearly identical with the specified slopes (change in timing vs change in rpm).  This is why I ask whether you're absolutely sure your idle timing at 850 rpm is actuall BTDC rather than ATDC.  

If my conjecture is correct, then the problem is that you haven't rotated the distributor body to move the entire curve for your timing to the left (actually to move the curve down...i.e.  to get it to overlay the spec'ed timing range (timing vs rpm)).

Please, please pardon the following description of ignition timing procedure if you're already doing it. Rotating the distributor body a few degrees one way or the other simply changes the point in time when the points open relative to cyl. #1 TDC.... rotating the body doesn't rotate the shaft, rather it rotates the points... dwell (point gap) doesn't change since that's always set / measured with the movable point contact cam sitting on the distributor shaft cam's high point.... regardless of where that high point is in the rotation... but normally the way the distributor is designed, it's going to be with cyl. #1 at TDC.  There's a nut that clamps the distributor body to the block... so it can't rotate during operation.  Loosen the clamp nut slightly, rotate the distributor body slightly one direction (or the other) while engine's at idle with your strobe light checking the timing marks at the counterweight.  When you think it's rotated so that timing is where it's supposed to be (2-4 degr ATDC at 800 rpm... 1-3 degr ATDC at 850 rpm, without vacuum), tightend the clamp nut and check again (to make sure the distributor body didn't move while you tightened the clamping nut. Then go on and check the timing at 1500 and 3000 rpm and some higher rpm (up t 4500 no-load, without vacuum).. the 3k and up to 4.5k rpm timing should be the same (not changing) and should be 30 degr BTDC.

Regards your BBB vs mine, for the 230SL my BBB is updated thru March '67 spec's on the pages of tables related to timing for each Bosch distr. type and 230SL and 250SL versions.... and yes, the idle timing is without vacuum... which is stated in the table as well as emphasized in bold type in the section related to ignition timing (also updated to March '67). For the ...051 distributor the timing at idle without vacuum spec's are 2 degr ATDC (+2 degr, -0 degr)... for spec's as of March '67.


Longtooth
67 250SL US #113-043-10-002163
The 6% Club - Best of the Best
'02 SL500 Sport