Setting the timing on an M20B23

[bloodsnot]

Hello all,

This is my first post here and I'd like to send you all a "hello" from the colonies. I've found myself a sleek euro e30 in an old man's garage and have been renewing things here and there over the last year or so. Seeing as the 323i e30 was never sold in the states, I've found myself frequenting your forums for advice specific to my car.

I am usually pretty proficient with the search tool but this issue has caused me to finally make my own post. I'm struggling to find information about adjusting the timing on my '85 323i with L-Jetronic pulsed injection. The previous owner mentioned that he had retarded the timing a bit so as to run regular grade fuel (87 octane here in the US) without pinging. This brings a couple of questions to my mind:

1. Aside from loss of power, what other effects could this have on my M20?
2. What are the OEM timing specs? I've scoured the 'net up and down and can't seem to find them anywhere. The part number for my distributor is 12111706459.

I've never set the timing on any vehicle before but I'm assuming that there isn't much to it that I can't glean from writeups about different cars. Any tips on anything e30-specific about the process would be much appreciated.

Thanks all, any input is welcomed! Cheers

[Brianmoooore]

I have the timing specs. here for a 323. It varies with distributor, but the numbers I have for the type are completely different to yours.
According to my data, the distributor number should be 023730****, with **** being 2038 for 82-83, 2040 for 83-84 and 4025 for 85-86.
Timing for the first one (leaded petrol, and vacuum disconnected) is 19 degrees at 3000 RPM, and the last two are 16 degrees at 5000 RPM.

[bloodsnot]

Thanks for the input!

I have the timing specs. here for a 323. It varies with distributor, but the numbers I have for the type are completely different to yours.
According to my data, the distributor number should be 023730****, with **** being 2038 for 82-83, 2040 for 83-84 and 4025 for 85-86.

I got that part number from RealOEM for the whole distributor assembly (#2 in this diagram). Digging around a bit further leads me to believe that perhaps your numbers refer to the distributor cap itself (#1 in this diagram).

While the cap's part number (12111289519) doesn't match, I did find a clue buried the garbled text in the description column:

"Typ Nr.0 237 304 025/033 = 12 11 1 706 182 - 12 11 1 706 459"

That seems to have both of our numbers in there, doesn't it?

Timing for the first one (leaded petrol, and vacuum disconnected) is 19 degrees at 3000 RPM, and the last two are 16 degrees at 5000 RPM.

Thanks very much - I believe those are the right numbers.. but we've only got unleaded fuel here in the states. A quick Google search leads me to believe leaded petrol's pretty hard to come by in the UK as well - do you just use it for timing procedures?

[daimlerman]

Be aware that the distributor is driven off the same jack shaft as the oil pump.This,in turn, is driven by the cam belt.On these early engine's there is an extra timing mark on the jackshaft pulley that lines up with a mark on the lower belt cover,this is very easy to miss when doing a cambelt swap and then the ign timing is re-set by turning the distributor body until the engine will run....

The old fashioned way of timing up an engine involved setting number one piston at TDC on the firing stroke(both valves closed)with the rotor arm pointing to the correct HT lead and then fiddling from there to get the best engine running possible.

[bloodsnot]

Thanks for responding!

On these early engine's there is an extra timing mark on the jackshaft pulley that lines up with a mark on the lower belt cover,this is very easy to miss when doing a cambelt swap and then the ign timing is re-set by turning the distributor body until the engine will run....

Bear with me here as I'm not quite clear on this. Do you mean that if you mistakenly forget to line up this extra timing mark then rotating the distributor to compensate isn't good practice? Why, exactly? Apologies if that's a stupid question..

The old fashioned way of timing up an engine involved setting number one piston at TDC on the firing stroke(both valves closed)with the rotor arm pointing to the correct HT lead and then fiddling from there to get the best engine running possible.

Spoken like a true sage of internal combustion

[daimlerman]

Rotating the dizzy to compansate is a whole lot easier than draining the cooling system and re-fitting the belt!

I wanted you to be aware that there is a 'proper' way of setting the thing and to watch out for this practice when you get around to doing a cambelt swap!
If you cannot see these marks line up when the cam and crank are on their marks,I would create a new mark,before removing the old belt,then at least I would have a starting point.

And yes,I admit to being a touch older than most zoners....

[bloodsnot]

Rotating the dizzy to compansate is a whole lot easier than draining the cooling system and re-fitting the belt!

I wanted you to be aware that there is a 'proper' way of setting the thing and to watch out for this practice when you get around to doing a cambelt swap!
If you cannot see these marks line up when the cam and crank are on their marks,I would create a new mark,before removing the old belt,then at least I would have a starting point.

Much appreciated. Luckily the car came with documentation of the belt being done ~2k miles before I purchased her, so I've got some time yet. Sounds like I can save myself a bit of work by doing this right when the time comes.

And yes,I admit to being a touch older than most zoners....

Well, your location does say "Grumpy Old Man" on your posts...

Thanks again!

[GooneriC]

The old fashioned way of timing up an engine involved setting number one piston at TDC on the firing stroke(both valves closed)with the rotor arm pointing to the correct HT lead and then fiddling from there to get the best engine running possible.

My dad did this for me on my Jetronic 320i , with very good results!

[bloodsnot]

My dad did this for me on my Jetronic 320i , with very good results!

Well ship him over!

I am curious - does anyone know if leaded fuel is helpful for timing adjustments?

I could see it preventing pinging if you were swinging the adjustment around wildly or something but don't know why it would be called out in Brian's data:

Timing for the first one (leaded petrol, and vacuum disconnected) is 19 degrees at 3000 RPM, and the last two are 16 degrees at 5000 RPM.

[daimlerman]

At three degrees,the difference is less than 1%,so pretty marginal IMO.
If the engine is running fine,I would suggest that you leave well alone.Retarding the ignition slightly should improve running on lower octane fuel,this is something that may be worth experimenting with.
In the UK,we can buy fuel additives to boost octane ratings,these were widely available when unleaded fuel was first introduced,but are now much harder to find.
BMW do use an alloy head with hardened valve seats,so the effect of unleaded fuel is marginal as far as valve seat damage is concerned.

Looks to me like the figures that Brian quoted at the top of the page are for use with a strobe light,back in the olden days when I used to own such a gadget I found that marking the timing marks with Tippex would make them stand out in a gloomy engine bay.

[bloodsnot]

Yet again you bring the wisdom, kind sir. And Brian - thanks for the specs! I'll get around to fiddling with it some day but I've got vacuum lines to replace in the meantime while I save up to have some Tippex shipped over

Thanks again, gents!