Issue with the latest version of the 123 ignition

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Neil Bardsley
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Re: Issue with the latest version of the 123 ignition

#61 Post by Neil Bardsley »

Cliff what are the advantages of running with the vacuum advance/retard feature? How does the curve look on load v advance?

Also it sounds like a rolling road would be needed to setup this extra dimension correctly?

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C J Murray
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Re: Issue with the latest version of the 123 ignition

#62 Post by C J Murray »

Hi Neil,
What you have are two separate curves, centrifugal and vacuum, that are totally independent but the results of each are added together to get the final advance total. Either curve could be programed to produce a negative advance; retard. The "centrifugal" advance in the 123 is very accurate because it is really controlled electronically. You can set any curve you wish and make any screwball curve you want based on the rpm of the engine and it will make that number for that rpm. You can't go up and down like that with a mechanical advance nor can you make the curve as concave or convex as with the 123. In reality most engines don't require anything too weird but some touchy engines can benefit. The vacuum advance uses a MAP sensor like a modern car to monitor the manifold vacuum and that reading is effected by everything, throttle position, wind resistance, incline, weight, acceleration rate, and more. At wide open throttle there is basically no vacuum and the engine runs the timing based on the centrifugal advance numbers and this curve should rise as quickly as possible without causing any pinging. Usually this is about 3* less than pinging so that fuel quality can vary a little without pinging. If you are racing or road driving with your foot in it all the time there is no need for vacuum advance. If however your car sits at idle or is driven at light throttle then there is a big advantage to advancing the timing while the engine is under light load. Idle and light throttle operation causes very slow burning of the mixture and the combustion is incomplete when the exhaust valve opens unless you fire the plug earlier than you do at WOT. Because the combustion is not complete the flame is wasted and the flame overheats the exhaust port and exhaust pipes. The engine runs hot and has poor fuel mileage.

I have been tuning with the 123 Tune for 2 years. Unfortunately I had some mixed results but not because of the distributor. I have 18K miles on the 2133cc engine with a US cross country trip and it worked ok but was too sensitive to fuel and heat and exhibited some pinging. Because the engine was always on the edge of detonation it did not respond well to timing changes. I have just removed some compression and it now responds normally to tuning changes and there is no pinging even with an aggressive ignition curve. Now I have been better able to utilize the vacuum feature.

So, the basic curve is determined exactly the way it is on a distributor without vacuum. You should tune this with the vacuum plugged. Once you have the basic curve set you hook up the vacuum. You make a vacuum curve with maybe 10* of advance at high vacuum and dropping to 0* at a very low vacuum. Then you find the point that just barely gives 10* advance at idle and that is the high point on the curve. The low point, zero degrees, is then placed around 1/2 the way to zero vacuum point. Then you see how the car runs at less or more degrees of vacuum advance. You never change the other curve.

Driving say 60 on a flat road with the throttle nearly closed you will have 35* plus 10* for a total of 45* but as soon as the throttle is pushed to accelerate the vacuum drops and the timing goes to 35*. You get a very positive response because the engine is running more powerfully at cruise with the extra 10* and then when it gets to WOT it removes the then unnecessary 10* of timing. Your engine will feel much more powerful in any situation at any speed where you go from light throttle to larger throttle openings.

It is not really that hard to tune the vacuum curve once you have experimented a little. You don't need a rolling road.

I am sorry about being so sloppy with my explanation but I have found it more difficult to explain than to actually do.
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Wes Bender
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Re: Issue with the latest version of the 123 ignition

#63 Post by Wes Bender »

Thanks CJ. That's about as clear as I've ever heard it explained.

Cheers,
Wes
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Re: Issue with the latest version of the 123 ignition

#64 Post by Bill Oldham »

I second Wes's approval of CJ's explanation. Now another silly question. If one gets into this making up their own advance curve it would be great to have a real knock detector, beyond what we usually use ... our ears. Frankly I do not trust my ears, lacking the kind of experience that seasoned mechanics have. Is there some kind of knock detector one can buy... they exist on modern engines especially with turbo, so the technology is there. But is there a manual detector/gauge tool that is available to help us tune compression/advance?
Bill

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Neil Bardsley
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Re: Issue with the latest version of the 123 ignition

#65 Post by Neil Bardsley »

Thank you Cliff

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C J Murray
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Re: Issue with the latest version of the 123 ignition

#66 Post by C J Murray »

Bill Oldham wrote: Is there some kind of knock detector one can buy...
I'm not aware of one.
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Re: Issue with the latest version of the 123 ignition

#67 Post by Ronald Sieber »

This has been quite a topic to cover, and I too would like to read of a knock sensor if one is ever developed. Gas quality is rather variable nationwide; you almost have to calibrate your car for where you drive.

The whole topic modern timing solutions would make for a great technical bulletin. Thanks to all, especially Cliff, for taking this ball and running with it.

=rds

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Re: Issue with the latest version of the 123 ignition

#68 Post by Dave Erickson »

CJ, nice summary of vacuum advance! I think to complete the picture we should talk about where to pick up the manifold vacuum. Solex 40PII split shaft carburetors have a vacuum port that appears to be ideal, i.e. it is well below the throttle plate, exposed to full manifold vacuum. Porsche also provided aluminum blocks that were installed below 40PII's, that had vacuum ports in them. Were these ever used with vacuum advance distributors on the 912, or were they just for mechanics to use to measure manifold vacuum?

I have never seen a 40PII with a "ported vacuum" connection (i.e. above the throttle plate), so where did the later 912 vacuum retard distributors pick up their vacuum?

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Re: Issue with the latest version of the 123 ignition

#69 Post by C J Murray »

Hi Dave,
Only yesterday did I notice a picture of a Solex with vacuum ports at the very bottom that I had not seen before. I have seen the carb mount spacers though. Emissions control back then was pretty crude and did the engine no favors. I'm not well versed on how they worked but when I worked at the foreign car shop in the early 1970s we had difficulty getting them to run well and saw some premature engine failures. I don't think the vacuum retard could be too many degrees or the engine would run really hot, don't know. I do remember cars with various valves controlling the flow of vacuum based on temperature. What about the air pump system? The whole mess was anti-sporting. The chemists among us can maybe explain how doing everything wrong results in fewer toxic emissions.
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Vic Skirmants
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Re: Issue with the latest version of the 123 ignition

#70 Post by Vic Skirmants »

Those spacers were steel, and one on each side had a vacuum port. They were part of the emissions control.

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Re: Issue with the latest version of the 123 ignition

#71 Post by Sam M. Shiver »

Gents, I'm very interested in replacing my Bosch 022 with a 123 distributor on my stock '64C engine, but after reading all the posts to this topic, I'm confused as to the correct model 123 distributor, installation procedure, and curve setting. I'll be the first to admit that I'm as far from being an electrical engineer as a human can get...
Is there more recent experience and clear guidance since Feb 2015? Thanks
Sam Shiver
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Marshall, North Carolina

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Matthew Devereux
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Re: Issue with the latest version of the 123 ignition

#72 Post by Matthew Devereux »

Just call Ed and he will help you pick the right one. The manual is online which tells you how to install it and select the curves.
http://123ignitionusa.com/
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Dave Wildrick
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Re: Issue with the latest version of the 123 ignition

#73 Post by Dave Wildrick »

Sam M. Shiver wrote:Gents, I'm very interested in replacing my Bosch 022 with a 123 distributor on my stock '64C engine, but after reading all the posts to this topic, I'm confused as to the correct model 123 distributor, installation procedure, and curve setting. I'll be the first to admit that I'm as far from being an electrical engineer as a human can get...
Is there more recent experience and clear guidance since Feb 2015? Thanks
Both of my C coupes are using the 123 VW\R (no vacuum) with the curve set to "D."
I set both to 5 degrees of static advance, using the built-in green LED (in the plate beneath the rotor), as directed by the manual.
You set your old distributor to #1 at top dead center (TDC), remove it, and put in the 123 ignition.
When you go to set the static timing to 5 degrees before TDC, make sure you rotate the 123's body counter-clockwise to bring up the green LED, which appears through a small square window.
If you rotate the body clockwise, the light appears through a different window, and if you clamp the distributor in place at that point, the car will not start. I figured this out by trial and error, and there is no mention of this being an issue in the manual.
Other than that, installation/setup is pretty straightforward.
Dave Wildrick
Houston, TX
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65C coupe

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Joris Koning
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Re: Issue with the latest version of the 123 ignition

#74 Post by Joris Koning »

These 123's are pretty trick. A friend has developed a 4-cam version. I will be in the US soon and Adrian is going to see how it behaves on the dyno compared to the stock 4-cam ignition system
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Re: Issue with the latest version of the 123 ignition

#75 Post by C J Murray »

I installed the new 123 Tune+ today. The install was not without problems but the problems concerned the Bluetooth feature. The distributor had to have a program reset to correct the fault. Once that was done all was good. If you install one and the blue light behind the clear plug is flashing then there is a fault. To reset you move the black wire to the positive side of the coil, power up, and wait until the blue light goes solid. Return the black wire to the minus side of the coil and all is well. The manual is worthless and tells you nothing about the flashing light or how to reset the unit. That said, the Tune+ is very cool and the anti-theft feature works very well. If you want to steal my car bring a roll-back.
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