123 distributor fail - now success

[merrill]

hello
installed the 123 today, 

followed the instructions, car started and idled, went to adjust the timing with my timing light.
car died.

went back, re did the installation, car still will not run.   every once in a while i get a pop

0 231 116 051 old disti, used a timing curve of "8", re using bosch red coil.

e mailed 123 for technical assistance

[mdsalemi]

Wow, that's frustrating!
Keep us posted...

[Cees Klumper]

I always get confused with TDC - especially in the sense that there are two TDC's, one on compression stroke (that's the one we want to set ignition timing) and one on 'the other' stroke. It's very basic, and I always figure it out in the end, but I always have to be busy with it for a while, every time I need to 'time' an engine or ignition. So if it seems like you're on TDC, you may not be on the compression stroke and you have to rotate the engine again to what looks like the same point, but it's not, it's 'the other TDC'.

[VikDasor]

Hi Matt,

I had installed the 123 ignition while ago and I also remember I had to change the Ballast resistor too. May be look into that too.

Hope this helps.

[mdsalemi]

I always get confused with TDC...compression stroke

Found this to be useful: https://www.yourmechanic.com/article/how-to-find-an-engine-s-top-dead-center-by-ed-ruelas
For timing, the #1 piston at TDC on the compression stroke is the ONLY thing that matters. Note in the simple instructions on the link above, one of the first things they are having you do is ensure you are on the compression stroke.

If you are on the exhaust stroke (or "other") I don't think you'd see the marks line up on the balancer as it would be 180 degrees out...right?

When using a timing light after the fact--engine running and all that--you may find that the numbers and timing are hard to read. With the engine stopped and in near TDC position, best to clean the markings area and maybe highlight with white crayon or similar so you can better see with the strobe...

[merrill]

hello
thanks for the replies.

i went out before work on a very humid morning and found that the disti had popped out of the drive gear.
this is using the 123 clamp which is thicker than the oem.

will swap back to the mb clamp and try again.

now i am wondering if there is a memory in the 123 that needs to be cleared since it did work for a few minutes.

[merrill]

well,
ran home at lunch to mess with this.

after aligning the crank to "0" and the cam notch it seemed the rotor was 180 off.

ok, so rotated rotor, went to crank the car and the disti popped up out of gear.

decided to take a break and walk away for a while. but it i cant get it working i may just return the 123 and go back to setting points.

[Paul & Dolly]

It is unfortunately possible to fit the 123 distributor 180 degrees out.The drive lug is only very slightly offset so it is relatively easy to fit the 123 180 Deg out.

Paul

[merrill]

ok,
so got it to work.

thinking about the disti popping out of the gear i ended up rotating the rotor 180 degrees until i felt the disti lock in.

re did everything per the instructions and it started on the first try.

i have the timing set at 6 -7 btdc and at high rpm its about 37

now to drive it and enjoy.

[Cees Klumper]

Those 180 degrees get us every time!

Glad to hear you got it to go, I am sure you will not regret having installed this upgrade.

[Paul & Dolly]

Glad it's sorted now

Paul

[mdsalemi]

so got it to work…ended up rotating the rotor 180 degrees until i felt the disti lock in…redid everything per the instructions and it started on the first try.

Fantastic!!!

[dirkbalter]

Glad to hear you got it to go, I am sure you will not regret having installed this upgrade.

I agree.

(Don't blame the hammer if the nail doesn't go in) 

[wwheeler]

I believe the vibration damper is also just slightly offset like the distributor drive so you "can't" install it 180* off. Not quite enough offset and you can "make" it fit. Not sure why, but seems MB should have made the offset just a tad more.

[merrill]

lots of good replies,

it would have been nice if MB had the cogs more offset so it was more obvious how to install the disti.

It had been a long time since i had to R/R the disti, kinda caused my own issue..  lol

[MartinK]

Don't you think 37 advance is not a bit too much?  How did you proceed with the idle vacuum retard?

[Jordan]

I always get confused with TDC - especially in the sense that there are two TDC's, one on compression stroke (that's the one we want to set ignition timing) and one on 'the other' stroke. It's very basic, and I always figure it out in the end, but I always have to be busy with it for a while, every time I need to 'time' an engine or ignition. So if it seems like you're on TDC, you may not be on the compression stroke and you have to rotate the engine again to what looks like the same point, but it's not, it's 'the other TDC'.

Is it not possible to tell the difference between TDC on the compression stroke and the "other" (exhaust stroke) by looking at what direction the rotor is pointing?

[MartinK]

The most secure way is to have a look into the oil filler hole. There you can see the lobes of the camshaft cylinder 1. If the engine is TDC in compression stroke, the lobes are positioned upwards. If the engine is is in TDC gas exchange, the lobes are positioned downwards. There is no possibility to make a mistake.

[mdsalemi]

The most secure way is to have a look into the oil filler hole. There you can see the lobes of the camshaft cylinder 1. If the engine is TDC in compression stroke, the lobes are positioned upwards. If the engine is is in TDC gas exchange, the lobes are positioned downwards. There is no possibility to make a mistake.

GREAT INFORMATION!

[Benz Dr.]

Don't you think 37 advance is not a bit too much?  How did you proceed with the idle vacuum retard?

No. 37 degrees is pretty close to where you want to have full advance. I often run 38 - 40 degrees depending on application.