223 ignition advance and retard spec

[Rocketman1955]

I have a question about ignition timing spec.
I have just renewed the contact breakers on my 223. Before changing them I checked the idle (~850rpm) ignition timing timing.
The ignition was about 3 flywheel teeth (107 teeth on the flywheel) advanced vs the marks which equates to 10 deg advance ahead of the pegged marks which indicate static firing angle.
When I fitted the new contact breakers I set the idle timing so the flywheel/bellousing marks line up as per the pegged timing of 8deg BTDC.
However, when I drove the car although it was smooth to drive it had definitely lost some performance .
I then checked the dynamic ignition settings based on information in the Haynes manual eg firing at 32-42deg BTDC at 3000rpm.
Allowing for the static timing marks being 8deg BTDC I would expect to see 24-34deg advance from the timing marks , or 7 - 10 teeth.
My actual ignition was only 20deg ahead of the timing marks, 28deg BTDC. ie retarded vs Haynes spec. 32-42deg BTDC
I have now reset the idle timing 10deg ahead of the timing marks so that more advance is generated at the higher rpm when it is required rather than worrying about idle timing being too advanced. The car's original performance has been restored.
For info the car has Boyer Bransden electronic ignition and timing was checked with a strobe.
The mechanical advance & retard unit seems in good condition and lubricated.
I do not know the previous history of the car.
Is it usual for the timing to be retarded vs the Haynes spec if the pegged timing marks are used to time the engine?
Is the Haynes manual correct?

[Ken Hanna]

Rocketman,
all I can say is that if you try running with total ignition advance of 42*, it won't be too long before your engine suffers a partial (or even total) seizure.
To be safe from such a catastrophe when using 95 octane fuel, the total advance for an engine with 8.5:1 CR should be no more than 34 degrees and for one with 9.0:1 pistons, you're looking at 'around' 31 degrees.
.
These items on my Flickr pages might be of assistance...
.
https://www.flickr.com/photos/slcchassis/4313805292/
&
https://www.flickr.com/photos/slcchassis/25231808879/

Ken




[

[Rocketman1955]

Thanks for the input.
I do not know the history of my engine or the compression ratio.
I plotted out the 2 sets of advance curves from the Haynes manual to establish the the overlap and targetted that area to be 'safe'.
Checking the advance with a strobe, after intial advance from idle to ~1000rpm, it is then quite flat ~ 1.5 teeth / 1000rpm
vs the 5 teeth / 1000rpm at higher rpm in the Haynes manual
My strobe is good up to about 1500rpm, but it is a bit erratic at higher rpm (budget tool, but ok for setting idle timing!)
So, using the intermittent flashes I do get(!), I have set the timing to give ~5.5 teeth at 2500rpm ahead of the timing marks.
ie 18.4deg ahead of the timing marks, so depending on the engine & setting for the timing marks this gives either 26.5 or 30.5BTDC at 2500rpm.
This is in the 'timing overlap' area and should be safe.
This requires ~ idle setting 1.5 - 2 teeth advanced.
My only concern is that my advance unit curve is quite flat and at higher rpm (where the engine spends most of its life!) the advance might be a bit retarded, albeit safe.
Has anyone else plotted the advance curve their engine actually delivers?
The advance and retard unit appears ok & operates freely & is lubricated.
Do the springs work harden or deteriorate, are there other faults that develop?
Does the electronic ignition unit affect any of this, or is it simply triggered by the contact breakers opening?
How can I identify the CR of my engine?

[Rocketman1955]

The pegged timing on my engine has now been confirmed as 8deg BTDC.

To resolve the issue of having to use extra advance at low rpm to get reasonable advance at high rpm I am considering fitting one of the electronic systems that will replace the mechanical advance, contact breakers and Boyer Bransden module.

The ones I am looking at fit in the contact breaker box on the front of the engine.
However, I have seen comments that they may not be suitable for use on a Lomax 223 as they are not robust against water ingress.

Has anybody got experience of using these systems on a 223?
( I rarely go out in the wet & certainly do not intentionally go wading!)

On a different subject, my timing gun had only been working up to about 1500rpm.
I have now changed the spark plugs and it works at least up to 3000rpm!

[Lomax76]

I run a DGnition on my Lomax all year long even under heavy rain never had any trouble.. In a doubt you could protect it, can as well be spread with silicon..
I found it more difficult to have water proof bag if somebody have an idea on that subject

[Rocketman1955]

Thanks for the response - I had not seen this system before.

I am hoping to use the existing Boyer Bransden ignition coil (as fitted in the current Boyer Bransden electronic ignition) with the new system.

Does anyone know how sensitive these systems are to the type of ignition coil?
What are the risks of this combination?

[QFAD]

Ron,

I used the 123 basic electronic ignition (with the Yellow (ECAS) coil) on my VGS engine for 2 yrs (then I sold the engine - the kit is still fitted to Chris Days car) and despite driving in some heavy rain never had any issues. Mind you I always gave it a liberal squirt of WD40 at the start of the season.

In fact on one occasion I drove through a ford with the water depth 'just a bit' more then anticipated - the bow wave was very cooling, it being a very hot day; but the engine did not miss a beat.

I would fit and forget.... and squirt with said WD40 once in a while - makes you feel better!

[Rocketman1955]

I have now fitted a 123 electronic ignition and drivability at low rpm is definitely improved vs with the previous artificially high advance.
To reduce any water ingress issues I have sealed the pcb edge with silicon and also around the front face joint with the crankcase.
On examination the old mechanical springs they were not very stiff ( I have no idea how stiff they should be!) so I suspect they were going to full advance as soon as the engine started, hence the flat advance curve the engine produced.

[kawlomax223]

My 223 is running with a Lumenition system, a Boyer Bransden coil and NGK B7HS spark plugs. I have to say that I think that it runs rather well. Once set up the system needs absolutely no adjustment. The coil, which comes from Boyer with a heat sink is located onto one of the top bell housing bolts so that it is in more air flow to aid cooling.