a case where i should have just left it alone

[merrill]

66' 230 sl, auto, manual steering, 051 disti, red coil, white ballast...

the other week i ended up re torqueing the head, adjusted the valves and installed new plugs.

car ran fine, started fine, drove fine.

then i decided i'd throw in a new set of points....   
the old ones were very old (10 + years) and the dwell was at 36.1.  when i removed them they were pitted

anyway so after much trial and error i got the new points installed, dwell at 38.5 timing was just about perfect
and then the car died...

and wouldn't start... period

so i started messing around and found if i added a lot of timing it would start.   I am talking 20deg,  i could then
back off the timing and get it to about zero deg at idle then it would die.
wouldn't start again.

so started looking around,
1. Of all things the motor ground strap that goes from the front left corner of the block to the chassis near the ballast had broken...   luckily i had some new unused starter cable wire and with the help of my neighbor we installed a big lug , soldered and crimped it and then heat shrink wrapped the terminal.

new wire installed,  still no start.   but oh if i did the advance the timing thing the motor would start, i could back of the timing, it would idle then die.  then hard to start again.

so, i pulled the disti cap, checked the vacuum advance worked (from end to end) so there were no leaks, then
i found 2 things problems.   
First there is a little ground strap that goes from the point locking screw to the body of the disty , that had swung around and was close or was touching the rotor shaft  (first photo)
second the connector for the points was only secured by one prong, the other was sticking out , not sure if it was touching the disti body or not. 

anyway, corrected those 2 things

I also noticed that inside the disti was this black section with what looked like a soldering bubble under it. not sure if that is correct.  (second photo)

now the motor will only start if it pump the gas pedal while trying to start it, once its running
dwell is 38.7,   rpm 920 (its high) with vacuum connected  timing is at about  atdc 4 at idle and 27 btdc at 2800 rpm  ( think i am stating the atdc / btdc correctly)

I think i have resolved the electrical connection issues now i need to review the linkage tour and the starting aide tour as when i did the split linkage test the rpms went up from 920 to about 1270 - 1300.  ( need to back off the inj pump)

frustrating since the car actually ran fine before i swapped out the points.....

[merrill]

so, i definitely have a no spark issue.

with the timing light hooked up and cranking the car i do not have steady strobe, i might see a strobe but now none.

i swapped out my coil,  same symptom
checked my ballast  and its fine, though it does have a chip in it (photo)
added a jumper from the - coil to the connection on the disti no change.

i cleaned the both contacts at the ballast resistor, and both +/- on the coil.
even tried swapping out the high tension line from the coil to the distributor.

i am missing something,  I still have dwell at 38 pretty sure the points are secure and not floating.

new rotor, disti cap is in place securely.
even looked at the fuses, they all seemed ok
new condenser when i installed the points.

[Pinder]

the Bubble thing is a spring under it is a tiny ball bearing. It is part of the vacuum advance mechanism. It holds the vacum advance plate under slight pressure. the plate rotates. I took my distrub a part to clean this  plate and oil it up as it was sticking due to 50 years of crap in it. My timing was jumping around sometimes and that why I cleaned and oiled it up.

[ja17]

The condenser on the distributor must be grounded, make sure it is tight in its holder or you will have problems. Next, the threaded bolt going through the distributor body which the points wire and the distributor wire connect, must not touch grounded metal. Normally a small insulating sleeve covers and insulates the threaded bolt as it passes through the distributor housing. After all these years this insulating sleeve is often disintegrated or missing.

[merrill]

hi Joe,
well you are correct there was no insulator on the bolt where it passes thru the disti.  (photo 11)
 
i made a spacer out of some plastic i had laying around,   heat shrink tubing may have also worked. (photo 12)

one thing i did notice is the brown fiber washer looks like it should fit in the recess shown in the picture and center the bolt so it does not short out?

anyway,
the condenser clamp was not tight so i snugged it down tight 
reinstalled with the insulator i made, and that seems to have made a difference.
i now have steady strobe and the car did start and run, though its not entirely happy.
it started once again then it didn't want to start.
I noticed the strobe was not lighting and then it kicked on and the car finally started.

i was able to set the timing at 4 atdc at idle 790 rpm (turning the air screw) and 38.1 degrees of dwell.

car still does not want to start right up,  now i wonder if i have fouled the new plugs messing with this.

tomorrow i will pull the plugs and see how they look. 

thanks for the feedback and help

[merrill]

pulled the plugs and boy were they fouled,   hopefully i can clean them up since they were new.

i installed a new set of NGK's since i had them.

I also verified the points were not shorting to ground
removed the coil and condenser connection,  opened the points gap and using an ohm meter.
then verified the condenser was firmly secured in its holder and the ground was good using an ohm meter.

hopefully the car will start up this am.

not sure if its worth using a strobe at tdc to set the disti since i have marked the body and clamp so i have a good starting point

[teahead]

adjust the points again.

Happens all the time when points are too wide or too narrow

[merrill]

Joe
hi again,
i reached out to Ed Fall at vintage works distributor restoration,

he provided the history lesson below

"in the early to mid-'50's, Bosch employed a center bushing to keep that machine bolt centered in the hole in addition to the larger phenolic discs which fit into the recess in the distributor housing. Later, they discontinued the centering bushings and relied solely on the phenolic discs to keep the bolt centered which they did pretty well. As the discs warp from use and overtightening, they can get to a point where they no longer remain centered and shorting of the electrical impulse to the coil can result. The solution is either to install a bushing like you have or to refresh the phenolic discs."

thanks again
matt

[merrill]

well back to square 1.

i cant get a sold dwell reading anymore, i have tried to reset the gap (probably a mistake)

what happens is i get a spark (and strobe) the motor starts for a second or 2 then dies. 
while cranking / running the dwell drops and then comes back up.

i am not sure if i have a bad condenser, points or some other issue.

at this point i am about to pull the disti and send it to the repair shop to check it out.

attached is the current set up.

[Norm]

Hi Matt,

I have a 051 distributor ready to use sitting in a drawer if you want to try it.  I have a 123 set up but have used the 051 to confirm some tuning procedures and it worked fine.

Send me a PM if your interested.

Norm

[merrill]

Norm
hi,
thanks for the offer.

It worked fine until i installed the new points and condenser.

along those lines i just re installed the old points and condenser to see what happens.

according to Ed 
"The problem might be in the points themselves. If you have your old points, put them back in and see if you get fluctuation in dwell. If not, then I'd suspect the points. Sometimes if they don't fit snugly over the brass post on the contact plate there can be some wobble which causes a fluctuating spark signal accompanied by drift in dwell"

we will see tomorrow

[Pawel66]

Sorry to ruin the story, but there were voices some time ago about some lot of Bosch points being sold with faults. Couple of years ago. I heard it from several people. I did not follow as i decided to switch to 123.

[merrill]

Pawel
hi
lets hope the old points fix the problem then i can toss the "new" ones and order a replacement set.

thank you matt

[Benz Dr.]

hi Joe,
well you are correct there was no insulator on the bolt where it passes thru the disti.  (photo 11)
 
i made a spacer out of some plastic i had laying around,   heat shrink tubing may have also worked. (photo 12)

one thing i did notice is the brown fiber washer looks like it should fit in the recess shown in the picture and center the bolt so it does not short out?

anyway,
the condenser clamp was not tight so i snugged it down tight 
reinstalled with the insulator i made, and that seems to have made a difference.
i now have steady strobe and the car did start and run, though its not entirely happy.
it started once again then it didn't want to start.
I noticed the strobe was not lighting and then it kicked on and the car finally started.

I was able to set the timing at 4 atdc at idle 790 rpm (turning the air screw) and 38.1 degrees of dwell.

the car still does not want to start right up,  now I wonder if I have fouled the new plugs messing with this.

tomorrow I will pull the plugs and see how they look. 

thanks for the feedback and help

Why are you running 4 degrees ATDC when you should be running  8 degrees BTDC at idle? Could be all of your problem.

[merrill]

hi Dan

the car ran at 4 atdc at idle and 30 btdc at 3000 rpm (with vacuum hooked up)

i can try more advance.

[merrill]

just curious,  what is the purpose of the small screw circled in yellow in the attached pic.


the main adjustment point is circled in red

[merrill]

update
after re installing the old points and condenser ,

i had set the points using .305 mm feeler gauge,   when i went out this am there was no dwell.

i went ahead and re set using .33 mm feeler gauge 

first attempt the dwell was 10 and the motor started right up
reset points trying to close the gap just a bit
second attempt the dwell was 18 the car started right up

tried to reset again and must have messed up, no solid dwell reading and the motor would not start....

the 123 distributor is starting to sound better and better

will give it a go again later,   

[merrill]

Getting there

i finally am on the right track, i started using the small eccentric screw to make fine tune adjustments

anyway,   ended up with the following dwell readings, car started right up each time then i overshot the adjustment.
i have forgotten how much work it can be to set the points.

19.1, 22, 23, 26, 34.8  then 42

i think the last time i changed the points was 16 years ago.   a little out of practice

[Benz Dr.]

hi Dan

the car ran at 4 atdc at idle and 30 btdc at 3000 rpm (with vacuum hooked up)

i can try more advance.

I run 38 - 40 degrees of dwell and 38 degrees full advance with everything connected.

[merrill]

hi Dan and everyone

thanks for the replies.

i finally got it,   38.1 dwell, idle timing 2 - 4 atdc and at 3K rpm 30 btdc.  (vac connected)
 just glad its running at this point,  I think my mistake was not realizing that the "drag" on the feeler gauge was more than i remember.


I'll try a little more timing and see how it runs.

i see a 123 distributor in my future,

thank you again

[Pawel66]

I am by all means not an expert on that, and I switched to 123 quickly, but I remember from my youth that I figured to leave the gauge leaf between the points while tightening the screws. Sometimes a gauge one size thicker. I usually then got a gap I wanted.

[JN]

The small screw circled in yellow is for fine adjustment
But leaving the feeler gauge in while adjusting as per pawel66 suggested, is a a great trick

JN

[Benz Dr.]

hi Dan and everyone

thanks for the replies.

i finally got it,   38.1 dwell, idle timing 2 - 4 atdc and at 3K rpm 30 btdc.  (vac connected)
 just glad its running at this point,  I think my mistake was not realizing that the "drag" on the feeler gauge was more than i remember.


I'll try a little more timing and see how it runs.

Not even close to enough advance.  8 degrees at idle and 38 at 3,000 RPM.  What kind of spark plug wires are you running?

[merrill]

hi Dan
yup, i increased the timing to 8 deg btdc at idle and 38 btdc at 3K rpm.

i was running the bosch w7dc but substituted new 7333 ngk's since the bosh were fouled.

thanks for all the replies

[thelews]

Not even close to enough advance.  8 degrees at idle and 38 at 3,000 RPM.  What kind of spark plug wires are you running?

My 250 SL spec is 30 degrees advance at 3K rpm, doesn't specify vacuum or not, but there is no vacuum at 3K rpm.  It calls for 8 degrees at idle w/no vacuum.

The car starts, turns off and runs beautifully.