Ignition curve
Discussion
Seems to hit maximum centrifugal advance too early to be the lucas distributor, happy to be corrected.
Down the bottom of the page is a table derived from the lucas 35DLM8 distributor.
http://g33.co.uk/pages/technical-ignition-system.h...
Down the bottom of the page is a table derived from the lucas 35DLM8 distributor.
http://g33.co.uk/pages/technical-ignition-system.h...
Yes top left it where it starts for some reason, cant help much on the vacuum advance side other than the standard lucas module adds around 6 degrees total so it should be fairly east to plot.
The god damn shunt is killing me thread is a good read with regards to how the engine feels with some minor vacuum tweaks.
The god damn shunt is killing me thread is a good read with regards to how the engine feels with some minor vacuum tweaks.
I'm a long way from being an expert, but that jump from 12° to 22° is almost what I'd expect to see with a shunting engine - mainly because it's above idle, in a low but active rev range.
If I were to follow the wisdom of the 'god damn shunt' thread, I'd have it idling at nearer 18° before it progressing at your 1800rpm point.
But please don't take my thinking as information, rather a thought in relation to what I've understood of timing for our engines.
It would then be interesting to see if you get unacceptable emissions with the 123.
That said, I have just had mine through its MOT, and I forgot to shift the dizzy vacuum advance signal from full manifold back to ported, and I still got a pass with no advisories.
Which then makes me wonder if my vacuum module is working, and if my distributor is doing what it's supposed to...!
If I were to follow the wisdom of the 'god damn shunt' thread, I'd have it idling at nearer 18° before it progressing at your 1800rpm point.
But please don't take my thinking as information, rather a thought in relation to what I've understood of timing for our engines.
It would then be interesting to see if you get unacceptable emissions with the 123.
That said, I have just had mine through its MOT, and I forgot to shift the dizzy vacuum advance signal from full manifold back to ported, and I still got a pass with no advisories.
Which then makes me wonder if my vacuum module is working, and if my distributor is doing what it's supposed to...!
Hi Pablo. This is the nice nothing about the 123 you can play about with the settings. I can easily dial in 18 degrees and see how it goes. As for the mot mines due the end of May and I can always put it back to 8 degrees for the emissions. Luckily I have a local garage who are very classic friendly to take my car to.
This is a curve I just made based on COG post on piston heads
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Thoughts please.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Thoughts please.
A quick update. Tried the new COG curve out today and the car certainly does like this one. Only problem is the tickover is to fast . It will eventually get down to 950 rpm but driving it’s around the 1500 rpm coming to a junction etc. I tried dropping the idle from 18 to 12 BTDC but made no difference. I wonder if this curve is to steep going to 25 BTDC at 1200 rpm. What you guys think.
Rob
Rob
It should have a high idle when slowing/changing gear, to keep the revs up between gear changes - mine sits at around 1200-1400 until the car has completely stopped, then it drops to around 950.
Have you adjusted the base idle using the idle screw at all?
That was the method suggested when increasing the advance.
Have you adjusted the base idle using the idle screw at all?
That was the method suggested when increasing the advance.
Hi Pablo.
No I haven’t that’s on the list to do. If I can sort this out complete with the 18 BTDC and a normal idle then this is the curve I will run with. Car seems very happy with it and the difference between this curve and the std is very noticeable. I still think a RR session is the way to go later this year.
Rob.
No I haven’t that’s on the list to do. If I can sort this out complete with the 18 BTDC and a normal idle then this is the curve I will run with. Car seems very happy with it and the difference between this curve and the std is very noticeable. I still think a RR session is the way to go later this year.
Rob.
Some folk find they have to tweak the idle screw through the seasons, as the engine reacts to cold/damp/warm/dry, I know of one chap who has a finely tuned engine who has to do this.
It’s very easy to experiment with as long as you work out where you’re starting from - by counting turns until it’s turning it fully closed then bring it back to where you started, then start tweaking by quarter turns.
You can also use it as an opportunity to clean out the idle screw passages by taking it out completely and cleaning it all up
It’s very easy to experiment with as long as you work out where you’re starting from - by counting turns until it’s turning it fully closed then bring it back to where you started, then start tweaking by quarter turns.
You can also use it as an opportunity to clean out the idle screw passages by taking it out completely and cleaning it all up
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