Technical Your thoughts on accurate ignition timing?

[fiat500]

It has been stated on here a number of times the 123 electronic distributor, in particular, needs to be set up using a strobe-light.
Equally frequently there are other contributors pointing out that some freehand adjustment can make the engine run more perfectly.
Prior to some engine shunting I plan to do I have just re-instated the conventional distributor. I found that a tweak of retardation on the static timing made the car run better. Overall it really does run better with points. I suspect that the springs may be worn giving a more sporty advance curve
The 123 is obviously very precise but the analogue nature of the points gives a nicer driving experience for me.
Next time the 123 is fitted I will be inclined to experiment with its static setting or to trial a couple of its alternative curves.
The whole experience tells me that in my case there is a relatively wide range of static timing settings that work, but that the best one isn't necessarily the precise factory setting.
I suppose that makes sense as not all fuel is the same, all engines will have different wear characteristics etc. etc.
so what are your experiences and would buying a timing light make me even more confused/dubious?:spin:

 

[jjacob]

On my car I disassembled the distributor, cleaned, lubed, and adjusted the free play. I removed the points and installed the Pertronix system.
Carburetor was cleaned, rebuilt and mixture adjusted.
Valves adjusted correctly.
Timing was set to 18 degrees at 3000 RPM.
When cold or hot the engine barely makes more than a revolution or two before starting and running smoothly.
Perfect. You really need to do all of this for the engine to start and run well.
The Pertronix system works so much better than the points. Faster starts, smoother running.
John

 

[fiat500]

John jjacob. That interesting discovery you made about the later 650 engines being specified at 21 deg seems to me to be some evidence that deadly accurate timing might be an unecessarly thing to seek.
https://www.fiatforum.com/500-classic/446335-maximum-ignition-advance-650-engines.html
I'm guessing that the more exotic profile of the later camshafts might be the main factor in this.
With so many engines having had changes to components even beyond the factory upgrades, there can't be all that many "standard" engines left.
It might explain why anecdotally, there have been a few people, including me, cheerfully accepting that a final, manual tweak really does the business.

 

[gordinir8]

I will totally agree with John, if you want to adjust the advance first do all the others including just in case if pulley marks are true and correspond to TDC.
Buying a timing light with this car will make you even more confused/dubious but go for one, it will help you get the picture better.
What makes me skeptical is how it is possible to have better results with the points and not with the full electronic ignition system
I have also discard the points and fit in a pic up and magnet system which is not a full electronic ignition system and my engine changed to far better from the very first crank. Are you sure your el. ignition is ok?
Also my car runs better at far beyond factory setting, i have set it to more than 22 maybe 24 degrees and for what i have reed from other owners here this tends to be a common practice.
Thomas

 

[fiat500]

. Are you sure your el. ignition is ok?
Also my car runs better at far beyond factory setting, i have set it to more than 22 maybe 24 degrees and for what i have reed from other owners here this tends to be a common practice.

I'm not saying the electronic ignition isn't good, it's just that on my car it isn't any better than the points. Also, it just feels a bit more lively and flexible with the points; and I know the car really well.
Thomas, you're saying something there that I think supports what I am saying about there being some mixed ideas on this timing thing. So if you and others even advance as far as 24 degrees. It's good if you have set by timing light and so you know what the timing actually is, but as long as I start from the proper static timing and don't go wild with my adjustment, does it really matter that I don't know the actual figure.

 

[gordinir8]

I'm not saying the electronic ignition isn't good, it's just that on my car it isn't any better than the points. Also, it just feels a bit more lively and flexible with the points; and I know the car really well.
Thomas, you're saying something there that I think supports what I am saying about there being some mixed ideas on this timing thing. So if you and others even advance as far as 24 degrees. It's good if you have set by timing light and so you know what the timing actually is, but as long as I start from the proper static timing and don't go wild with my adjustment, does it really matter that I don't know the actual figure.

No it doesn't, all it matters is the result and not the figure. I have a :devil: idea since i am not sure if i have achieve the perfect adjustment so here it is. Since i am a rc airplane modeler i am thinking to use my radio control system, connect a servo to the distributor so it can be able to remotely turn and adjust my timing while car is moving!!
Sounds crazy but it will be my optimal action.:slayer:

 

[fiat500]

Since i am a rc airplane modeler i am thinking to use my radio control system, connect a servo to the distributor so it can be able to remotely turn and adjust my timing while car is moving!!
Sounds crazy but it will be my optimal action.

No that doesn't sound crazy; in the olden days, cars did that anyway with a mechanical connection from the steering-wheel. They retarded the ignition when starting.
In modern cars the same thing will be done by computer although obviously, a distributor is not involved.

 

[F123C]

As said above, you need to check the veracity of the timing marks.

The max. advance was determined by the factory back in the day to give the best performance,economy,reliability etc. I wonder if all the engine testing was carried out in Italy (hot in summer)?

Back in the day, leaded petrol was used not the modern part-ethanol fuel we generally have nowadays. Iirc, ethanol is slower burning so needs extra advance of ignition timing to run well.

But if you advance the ign. timing, you run the risk of detonation etc. so you might have to retard the timing. This might explain why the max. advance is reduced on some later engines (mentioned by another poster above). Ambient temp. also plays a part. Possibly winter vs. summer mix of fuel also.

So everything becomes a compromise. No one setting is 'correct'. Whatever works best for your particular engine/ stage of tune/ modifications/ compression ratio/ cam specs/ type of fuel/ climate etc.
is probably the 'correct' setting.

Al.

 

[F123C]

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and would buying a timing light make me even more confused/dubious?:spin:

Peter, yes it probably would, especially if the marks wander around! :spin:

For those who haven't used a timing light before, please be very careful as moving items, e.g. pulleys, appear stationary when the light is shone on them and accidents can easily happen.

Al.

 

[F123C]

No it doesn't, all it matters is the result and not the figure. I have a :devil: idea since i am not sure if i have achieve the perfect adjustment so here it is. Since i am a rc airplane modeler i am thinking to use my radio control system, connect a servo to the distributor so it can be able to remotely turn and adjust my timing while car is moving!!
Sounds crazy but it will be my optimal action.:slayer:

Many cars had a vacuum advance unit on the distributor as well as the mechanical (centrifugal) advance. For some reason Fiat didn't. (afaik).
The vacuum advance was supposed to improve economy when cruising on light throttle openings (this is when vacuum in inlet manifold is high). There was also usually a small thumbwheel adjustment to provide micro adjustment to the ignition timing.

Thomas, maybe you could fit a vacuum advance unit to your distributor and control it by varying the vacuum applied to it?

Al.

 

[gordinir8]

I think that this will make thinks more complcomplicated Al, besides my engine is not overhauled yet so I don't expect to get the max out of it.

 

[fiat500]

I respect Al's knowledge, which is obviously borne of experience. I like it even more that I think it supports my idea that the timing has a lot of potential variation on different engines.
Even so, having seen a very basic timing gun on eBay for about £12, I'm at least going to find what setting my engine is on.

 

[gordinir8]

Good choice, it is good to have one even if at the end of the day our little cars prefer to work out of the envelope.

 

[fiat500]

Good choice, it is good to have one even if at the end of the day our little cars prefer to work out of the envelope.

Well said Thomas, and now maybe I should admit I was wrong to doubt everyone.
I have established one fact that I find interesting: with my engine definitely set on perfect static timing of 10 degrees, I made a mark in white paint 25mm forward on the pulley from the TDC mark and did the strobe thing. I was surprised to find that in order to get this maximum advance set correctly I had to retard the ignition quite a lot, ie. turn the distributor clockwise.
This made the tickover less smooth....nearly stalling, but I soon sorted that out.
So I may need to go on a long journey this week to be sure what difference that made. It sounds good, maybe a little bit quieter.
So thanks for the advice to everyone and maybe I am now convinced that this strobe timing is important.

 

[jjacob]

Hi Peter,
Static ignition timing is not that accurate. It should be used only to get the engine timing close enough so you can start the engine and make your final ignition timing with a timing light and then move on to adjusting the carburetor, after the dynamic timing is set, for best power and smooth running.
John

 

[gordinir8]

I think that fiat numbers are BS. I don't think that you can match 10 and 18 degrees as well as that you can't put this engine work awith Fiat numbers. I have some experience in BMW engines which are 1000 times more precise and all those numbers that manual gives are true.
The good thing is that we all have the same results more or less, that means that we don't do something wrong.
I mostly enjoy the discussion with you guys here.
Thomas

 

[thepuddlejumper]

Peter, my dad always listened to the engine when he was checking the ignition timing, old school. I do the same, although I am not as good as my dad. I fitted a 123 ignition set up several years ago using the static light on the unit, once running I adjusted it by listening to the engine just to get it to that sweet spot and it has only let me down once when I was in the middle of France. I had a lot of problems with condensers, the new ones didn't seem to last very long anyway I managed to stop and ask for help at a Scania garage and one of the mechanics came out to help, he loosened off the 123 distributor and adjusted the timing by the sound of the engine, that was in 2007 and it hasn't missed a beat since. It certainly runs smoother than it did with the points set up. I believe due to the variance in these engines you have to adjust each to suit its own charecteristics.

Ralph

 

[fiat500]

You make a good point Thomas, because if I checked the static-timing now I guess it would be way out even though the dynamic timing is perfect (by the book)
I almost feel that roles are reversed and I am becoming the one in favour of the accuracy. I agree with Ralph that what matters is what the engine actually runs like rather than the measurements. But my engine runs well throughout quite a large range of timing, the plugs look good and the fuel consumption is excellent; but I will try it for a bit at this new setting, which isn't one I would have hazarded by ear.
Next thing I will stick the 123 back on and dynamically time that with the strobe as already repeatedly encouraged to do by Tom in particular.
Maybe then I will reach the Nirvana of the perfect running, although I will be amazed if it gets better than this.
This tinkering seems even more time-consuming than restoring the car.

 

[F123C]

I always think that static timing is only for starting and idle purposes.
Plus it's the starting point from which the centrifugal/mechanical advance starts which affects how the engine runs as the engine speed increases.

No one has asked or commented on why ignition advance is necessary.

It's to do with flame spread in the fuel/air mixture, this takes a tiny amount of time, it's not instantaneous! So, as the engine speeds up, the pistons are moving faster and faster i.e. covering more mm's per sec. So if the flame spread takes the same amount of time e.g. micro/milli-seconds, regardless of engine rpm, this time is equivalent to more distance travelled by the piston. Therefore the timing point of ignition has to be advanced to allow the fuel/air mixture to burn and apply maximum downwards pressure on the pistons at the right time, not too soon as this would oppose the pistons moving up towards top dead centre, not too late as the pistons would be moving down the bores ahead of the expanding gas.

I'm not sure why maximum ignition advance stops at e.g. 3,000rpm rather than continue to increase up to max. engine speed.....

I know nothing about electronic ignition conversion systems such as the 123. Does this simply do away with the contact-breaker points? and still use the mechanical advance unit in the distributor?

I've read a little about 'mapped' ignition on full electronic ignition systems where the ignition point can be set at any point in the rev range of the engine and varied to suit engine load and other factors. Afaik, for set-up, this requires the engine to be run under load e.g. on a rolling-road (chassis dynamometer) or engine dynamometer. Has anyone here any experience with such systems being fitted to older engines?

Al.

 

[F123C]

I respect Al's knowledge, which is obviously borne of experience. I like it even more that I think it supports my idea that the timing has a lot of potential variation on different engines.
Even so, having seen a very basic timing gun on eBay for about £12, I'm at least going to find what setting my engine is on.View attachment 175865

Peter, thank you for your kind words.

Just a thought, if you use your timing light on your 900T, remember the crank turns anti-clockwise, so the moving mark on the pulley moves the 'wrong way' wrt the 0* mark !!

Al.