Issue with the latest version of the 123 ignition

[Dave Wildrick]

Last night I checked the advance on my newly installed VW\R (no vacuum) 123 with my Innova Equus timing light.
At idle (650-700), with curve "C" and with the static advance set to 5 degrees, I saw 9 degrees advance with the timing light.
At 3300 rpm, I saw 39 degrees advance.

I switched the dial to curve "D" (did not touch static advance) and still saw 9 degrees advance at idle, and got 35 degrees max advance from 3000 and beyond.
Looks like people using this distributor should stick to curve "D", as currently recommended by Ed Madak and Cliff Murray.

[C J Murray]

Dave, that makes me feel good. For once I have made a meaningful difference!

[Pascal Zundel]

Mine is set on C per instructions of the manufacturer. It works fine.
Will try D instead as I trust you know better.
Will let you know if there is any perceiveable difference from behind the wheel.
Best
Pascal

[C J Murray]

Pascal, check your timing with a light. It should be close to 5*idle and 35*full. The "C" might be 5*idle and 40*full which could hurt your engine if you ran wide open at high speed where the engine is working very hard. Around town at lesser loads should not be damaging.

[David Jones]

CJ I beg to differ, Static timing will be 5*BTDC while idle is going to be more depending on rpm I would expect a hesitation coming off 5 * at idle. Could be as much as 13 at 900 rpm. I usually shoot for 8 * at 800 rpm but don't worry too much if it is +/- 2 degrees as long as it is approximately 35 at 3100 rpm.

[C J Murray]

Hi David,
You got me thinking so I dug out the spec's book.

First, with the 123 it depends on your idle speed, exactly and precisely. The 123 does not start advancing until 800rpm and many 356s will idle under 800. Above 800rpm the advance follows an exact path until full advance is reached. There is no wide range of "correct" timing like you have with the stock distributor. With the 123 Tune you can create any advance curve under the sun.

With a stock mechanical advance the idle timing tends to jump around a bit because many have slightly floppy springs that do not pull the advance back and keep it there during the ebb and flow of rough idling power pulses. Sometimes the springs are so floppy that the idle races. On my stock distributor cars I make sure that the springs are taught at rest. I also reduce the advance range and depending on the engine I end up with less full advance or more idle advance, or both.

Looking at the spec's book the advance change range could be anywhere between 27 and 33 degrees and reach full advance anywhere between 2700 and 3300rpm. That is pretty crude and could explain why some cars drive better than others. It also points out the importance of timing the engine at full advance and just letting the idle timing be whatever it is or fixing the distributor to have the correct idle timing when it has the correct full advance timing. The book says that advance starts somewhere between 600 and 900rpm which again is crude. So in many cases a 356 would, might, sorta, maybe be at the static setting. I use slightly modified stock points distributors on my original spec cars and they work fine but you can see why they don't measure up to a computer controlled modern distributor.

You are not wrong in what you say but there is a lack of consistency that means that the situation differs from car to car.
Cliff

[David Jones]

I agree with all you say Cliff. I was only reiterating what the manual says. Like you I time for full advance and let the idle fall where it may unless it is too far out which is where I will intervene.

[Al Zim]

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[David Jones]

Al,
As a matter of interest I could hear my engine "pinging" but usually in 4th gear under under hard acceleration up the hill after Canada turn at Elkhart Lake. This from a 1200cc VW engine and I was wearing a helmet which must have muffled the knock. Then again the engine was only 6 inches or so from the back of my head so it was somewhat closer than in a 356.
I found that if I downshifted, then at the lighter load it did not ping and I could delay shifting until I hit 6000 plus up the hill on the start finish straight. This was with stock low compression 1200cc engine but running high octane race gas and 41 degrees of advance.

[C J Murray]

Pinging, detonation, is harder to detect in lower gears because the engine rpm changes too quickly. The best tests are done on a dyno but you can drive the car on a highway, up against the left safety barrier, window down, and you accelerate from 2500rpm in 4th to as high as you are comfortable doing. The engine, any engine, will be most prone to detonation at it's peak torque rpm where it's volumetric efficiency is highest and the cylinder pressures are highest. For most 356s this is between 3000 and 3500rpm. Volumetric efficiency is also highest when the throttle is wide open. So, you're cruising along in the passing lane in 4th at 2500rpm and you put the pedal to the floor and listen for pinging as the car accelerates. A narrow range of pinging is a minor adjustment needed and a wide band of pinging means you better fix it fast.

Below 3000rpm the advance curve in the distributor could cause pinging but no engine damage is likely because the engine is not worked long/hard at those rpm.

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[Pascal Zundel]

Last week I drove about 2000km with the car. I shifted from C to D curve midway. As far as I could judge it only improved smoothness and regularity in power distribution. Will stick to that.

[Bill Oldham]

this is an old topic, quiet since 2015, but I have some questions that were not answered in the discussion.
1) What model of 123 is the correct one for 356 (they seem to have several that they label "356". Is it 123\PORSCHE-4-R-V ?
2) One their website they imply that one can see the advance curves, but I cannot fine them. Would be nice to see what they actually look like.
3) I seem to remember from some other discussion that Cliff liked vacuum advance. Anyone else have opinions on that? (For street use, not racing) I am not anxious to be tapping manifolds for vacuum, so there would need to be significant benefit.
Thanks for any update
bill

[C J Murray]

Hi Bill,
123 has a super duper new new new version of the Tune model that is programable from your smart phone. The previous Tune model required a cable connection to your laptop to program. You probably don't really need a Tune model unless your engine is modified heavily.

The 123 Holland website has been cleaned up a little and simplified. It was really confusing before with too many options. I was there yesterday briefly and I think I only saw one distributor that covers the 356 and the 912. I will take a closer look today.

The vacuum advance feature is of no value for racing but works well on the street. It only advances the timing when vacuum is high such as at cruising speed. This is done because the mixture burns more slowly when the throttle is not wide open and a centrifugal advance curve is the ideal curve for WOT operation. When cruising it is best to fire early so that the burn is finished before the exhaust valve opens. This improves fuel mileage, reduces temperatures in the ports and exhaust, and improves the throttle response when the throttle is tipped in. Back when the 356 was made these things were known but I guess Porsche felt that their customers would be driving aggressively where vacuum advance would not come into play very often.

Here is their Porsche selection... http://www.123ignition.nl/brand/Porsche.html
It looks like there is only 1 choice, with vacuum, which you could use without vacuum if you wish. People with Weber carbs may have vacuum ports on their carbs or there have been some Solex carb spacers that have vacuum ports or you can tap the manifold. Click on the manual link for more detail. I think the various curves are shown.

Cliff

[Ed Madak]

Hi Bill
Yes there are still two switched models that list the 356 and both can be purchased with or without vacuum. For ex VW-R or Porsche 4-R.
There are small differences in the all in advance @3100 or 3000 rpm
Porsche 4-R Curve 6 Starts 0800 rpm, all in 3100 / 30,0
VW-R Curve C Starts 0800rpm, all in 3100 / 35,0

Some Tuners do prefer the VW-R
http://123ignitionusa.com/123ignitions/volkswagon/
http://123ignitionusa.com/porsche/

Hope this helps
Ed