123 ignition

[Matt17t]

Hi all,

We have a 123 ignition with 16 pre set curves which curve number is best and do you have the timing at TDC or the factory specs ?

[Alec]

Hello Matt,

non of those curves will match the Triumph ones.
You need to see what the maximum advance for your car is (you didn;t say what model) and selct curves that match that maximum (Mechanical), You may have a choice of four, from mermory?

what the timing figure for your car is depends on what model it is, there were a few different settings given.

Alec

[Matt17t]

Hey Alec,

We have a triumph 2500tc just rebuilt our engine,

How do we find out which curve would be suit the factory one ?

[Alec]

Hello Matt,

the distributor should be a 45D6 Lucas number 41624.
No advance below 400 rpm,
1 to 6 degrees at 1200 rpm,
5 to 10 at 1400 rpm,
9 to 14 at 2800 rpm.

I am a little surprised at the spread of advance given by this data?

This gives 14 degrees maximum mechanical advance plus the 10 degrees BTDC static timin, I.e. maximum total mechanical advance of 24 degrees.

The vacuum unit starts advancing at 6 inches mercury with 3 to 4 degees advance to a maximum of 18 degrees advance at 10 inches mercury.
I don't know if the 123 has a vacuum advance function?
All angles quoted are crankshaft angles.
As amatter of interest my P.I. has a maximum of 30 degrees mechanical (22 total plus 8 BTDC timing), the workshop manual lists very many different distributors all with slightly different curves or static timing.

Alec

[Joe™]

The 123 does have a vacuum advance funcition.

Here is the chart of the curves on the standard (non-customisable) unit:



As Alec said it does depend on your engine, but if it helps I run an earlier Mk2 PI engine with HS6s and have mine set on 'B'.

[Alec]

Hello Joe,

thanks for that chart, but to me, none of those settings is close to the original.

I know many people are happy with this system but generally they are fitted to replace a totally worn out distributopr which may or may not even be the correct one for the car? it's not surprixing that there is an improvement but they are far from optimum. The trully programmable one is much better but it is not cheap, certailny much more than having the original distributor rebuilt and calibrated properly. Some owners enjoy using a lap top and tuning the car with it which is fine, it's up to you?

Alec

[Joe™]

Hello Joe,

thanks for that chart, but to me, none of those settings is close to the original.

I know many people are happy with this system but generally they are fitted to replace a totally worn out distributopr which may or may not even be the correct one for the car? it's not surprixing that there is an improvement but they are far from optimum. The trully programmable one is much better but it is not cheap, certailny much more than having the original distributor rebuilt and calibrated properly. Some owners enjoy using a lap top and tuning the car with it which is fine, it's up to you?

Alec

You are quite right, I fitted mine for 2 reasons, firstly because I had an incorrect and old/worn out distributor that came with my replacement engine and secondly for reliability.

I know quite a few people on this forum hold originality to heart with their cars but to be quite frank I hold driveability higher, and with the 123 I can be confident my car will start, hot or cold, every time.

Obviously my setup is not a factory setup so putting either a PI or TC spec Lucas distributor in wouldn’t be optimum either.

[Alec]

Hello Joe,

my car is far from original, although it is altered mainly with Triumph parts. I also value driveability and reliability and that can also be obtained by maintenance.

Alec

[Matt17t]

Thanks guys, we think it may have slight pinking we have it on curve b with 10degrees static timing