DIY - 123 Distributor Ignition Timing with Carburetors

I'm embarking into new territory regarding the potential of the 123 distributor that I think is being overlooked. I am no engine expert but from my research on the web (dangerous I know), that old school tuners used to set initial timing with a vacuum gauge and/or a "highest idle" procedure. From what I have determined, engines typically like more initial or static advance than the owner's manual suggests (for emissions and/or erring on conservative), all you have to do is twist your distributor counter clockwise and see for yourself just how much. This indicates a more efficient fuel burn at idle. Free power. The racer discussions are in favor of setting the idle advance as high as the engine likes, until adding more no longer results in a higher vacuum or idle rpm, then back off a little to compensate for fuel quality etc. Especially if you have a bigger cam like I do. The issue that always comes up is that if you do that, then total advance (when you add in the mechanical advance spec'd in the distributor) you'll have too much all-in and your engine will ping at best or grenade at worst. However this argument is moot with the 123 because you can control the "mechanical" portion with a computer or iphone.

I have said before that one of the great things about the 123 with Weber sidedrafts is that you can adjust the throttle plates to the perfect position in regards to the first progression hole (a critical adjustment for off-idle performance) by compensating either up or down with the static timing to achieve proper idle rpm. This was not possible back in the day so people compensated by opening up the throttle at idle or putting in less than ideal jetting. I have proven this to myself too many times. So this has led me to the next step down the rabbit hole in that now I am experimanting with an even higher static advance because recently, just for kicks I bumped my initial timing up to where the idle responded to the max which turned out to be about 25 degrees btdc. Every engine is different based on age, compression ratio, cam etc and it will tell you when you've gone too far when the idle or vacuum drops off. I then programmed the distributor curve for 11 more degrees from idle to all in 3000 rpm so total advance is still 36 btdc which is in line with spec. No vacuum advance. The only way to do this with a traditional distributor is to have it physically rebuilt, it can be done any number of times and configurations on the 123 in 5 minutes and of course is reversible. So why not said the curious cat.

The "snap" off idle and initial acceleration took me by surprise, it's amazing. One race builder site says this is how they build their engines - a lot of initial advance and only a little mechanical. I've read that Webers "like" a lot of advance. As does a bigger cam. However my Webers at 25 btdc required the throttles to be closed quite a bit in order to keep the idle at or below 1000rpm and so was hard to get the right smooth idle mixture. So my goal is to see what the point is where I can maximize static advace and still keep the throttle plates in an optimal posiiton for idle quality/AFR and will post my findings here for any others interested (if any :p ).

In the meantime I'd appreciate any opinions or other precautions by heading in this direction. The off-the-line acceleration is most defintiely better than my stock timing specs. Here is the curve I'll be tweaking, I suspect it will end up somewhere between 25 and the 15 initial advance I am using now:

Screen Shot 2019-12-20 at 1.09.11 PM.png
 
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shanon

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Yes, great write up/thread and inputs. Thx guys.

Going down the triple rabbit hole and got her 'running' and idling at 1000rpm.

Now looking at the dizzy....i think it is an older vacuum unit (two lines, top and bottom) and wondering if I should plumb lines (to where?)

Or if I should just ditch old dizzy and blue coil and go 123 bluetooth and new coil units.

The 123 eliminates the vacuum lines correct?
Which coil works best, blue or red?

Thx...learning alot
 

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Stevehose

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Webers don't need vacuum advance but if you have vacuum ports on your model webers you can use it with your 123. It's manifold sourced vacuum so it won't work with a traditional distributor. The bluetooth model 123 has a vacuum advance simulator which I use to add 8 degrees of advance for highway cruise using my vacuum ports. The red coil is better for this application than a blue coil which is internally resisted. The 123 is far superior to the old school distributor when using triple webers for reasons I have outlined in this thread.

If you want to keep your existing distributor just cap the advance and retard ports on the distributor and cap any vacuum ports you may have on your webers.
 

m5bb

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Webers don't need vacuum advance but if you have vacuum ports on your model webers you can use it with your 123. It's manifold sourced vacuum so it won't work with a traditional distributor. The bluetooth model 123 has a vacuum advance simulator which I use to add 8 degrees of advance for highway cruise using my vacuum ports. The red coil is better for this application than a blue coil which is internally resisted. The 123 is far superior to the old school distributor when using triple webers for reasons I have outlined in this thread.

If you want to keep your existing distributor just cap the advance and retard ports on the distributor and cap any vacuum ports you may have on your webers.
What Steve said, although on my much modded engine I am not using any vacuum advance.
One thing I will mention.
The 123 dist is really cool and great for adjustment.
One problem is the way they are made for the BMW M30 motor has some design problems.
Oil is drawn up the drive shaft with the gear at the bottom and eventually the oil destroys the module in the dist housing and it quits working.
I've already replaced mine once ($450) after 6000 miles and now with an engine that runs 60psi oil pressure at 3000 RPM it may be happening again.
Spoke to the US Dist (John) about this and they say it the BMW engine that causes this and basically nothing they can do.
I call BS and know that the shaft could be sealed with an O-ring to prevent the oil from coming up the shaft.
Tomorrow I am going to take my 123 out and try the stock dist and see if my engine miss at 2000-2500 rpm goes away.
It has been getting progressively worse the last few weeks as I have been driving the car a lot more.
If it seems to be the 123 then I will take it apart and see if I can see oil in the main chamber where the electronic module it located.
Then I may take the shaft out and see about putting in an O-ring.
I'll update this when I know more.
Gary
 

HB Chris

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Webers don't need vacuum advance but if you have vacuum ports on your model webers you can use it with your 123. It's manifold sourced vacuum so it won't work with a traditional distributor. The bluetooth model 123 has a vacuum advance simulator which I use to add 8 degrees of advance for highway cruise using my vacuum ports. The red coil is better for this application than a blue coil which is internally resisted. The 123 is far superior to the old school distributor when using triple webers for reasons I have outlined in this thread.

If you want to keep your existing distributor just cap the advance and retard ports on the distributor and cap any vacuum ports you may have on your webers.
No need to cap at the dizzy, just at the carbs.
 

shanon

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Thanks guys.

Here's a pic of what we're dealing with....

Stoked ;)
 

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Drew Gregg

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Thanks guys.

Here's a pic of what we're dealing with....

Stoked ;)
Shanon--Where is your valve cover vent hose going? I want to replace the K&N filter I have on my cover as it drops oil under it. Thanks, Drew
 

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shanon

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Hi Drew,

I have the valve cover vent hose going to a catch can. See pic. Yes, my bay has been 'manipulated'. Battery relocated to trunk.

Hth!
 

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JFENG

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I want to replace the K&N filter I have on my cover as it drops oil under it. Thanks, Drew
In 1983 I did a fresh 3.2L swap with DCOE’s into my E3. I had exactly the same K&N on my breather neck and it dropped like yours. A very wise man from NJ told me to get a long piece of hose plus an elbow joint and and run the breather down between the carbs where it vented toward the ground.

Alternatively, you can route it to a catch can.
 

Drew Gregg

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Yes indeed. I see your 5MPH bumper is now a set of Super Oscars. Now that's some manipulation....!! What is the bottle next to the catch can?
 

Drew Gregg

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In 1983 I did a fresh 3.2L swap with DCOE’s into my E3. I had exactly the same K&N on my breather neck and it dropped like yours. A very wise man from NJ told me to get a long piece of hose plus an elbow joint and and run the breather down between the carbs where it vented toward the ground.

Alternatively, you can route it to a catch can.
John-- Your idea was also given to me by Carl Bennett at Korman Autoworks. Now I need to find a 90 degree fitting for the valve cover. Carl told me to attach the K&N to that long hose.---Drew
 

shanon

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2nd little is a catch can for the water. Not allowed to drop any fluids on track.

I had the hose previously routed to under the car. It ultimately just made the underside of car messy but engine bay stayed clean... ;)
 
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