Thread: Programmable Ignition Timing

The Black Box was US$199 and another US$50 postage. I think it came to around AU$330 all up.

Hi Richard,
very interested in this, but unsure of the figures shown in your table.
45 deg is way too high as far as I know.

Could you explain the numbers going across at the top, the revs are obvious
As the advance changes across the table. are they vacuum or something else.

I was sent a rough advance curve table by Lloyds in UK, they recommend never go over 34 deg max.

Just trying to understand.

The numbers across the top of the table (the -ve numbers) are inches of vacuum, my car when warm and idling produces around 19, which in the table would be -19. So the LH Side figures on the top are higher vacuum figures than the right. To get the -1.9 on the RH Side that would be full throttle.
The MAP I put up is one supplied by the company, it is more than good enough to get the car going and to drive it. The 45 degree figure is with the engine with high revs, so all the mechanical advance in and with a light throttle, so most if not all of the vacuum advance in. I agree 45 degrees is a bit high. In the MAP I am running at the moment I have dropped this figure to 40 degrees. So 20 initial (for LPG) plus 10 mechanical plus 10 vacuum which gives 40 degrees. 20+10+10=40.
My old distributor I used to set at 12 degrees and it had 20 degrees mechanical advance plus 12 degrees vacuum advance. So at high revs with little or no throttle this would give 12+20+12=44 degrees.
So with this unit I can increase the static timing to 20 degrees but then not have a total of 52 degrees, which would come from the 20 initial + 20 mechanical + 12 vacuum.

The 34 degree max Lloyds are talking about would be the number in the bottom right hand side of the table. Full throttle (so no vacuum advance) and high revs (so all mechanical advance in). To get this figure add static timing and the timing provided by the mechanical advance.

Originally Posted by Richard Kaye

The 34 degree max Lloyds are talking about would be the number in the bottom right hand side of the table. Full throttle (so no vacuum advance) and high revs (so all mechanical advance in). To get this figure add static timing and the timing provided by the mechanical advance.

It'd be interesting if you set it at the old school ballpark of 14+14+14 for lpg (as per previous posts / links) and see how it went.

DL

Thanks for the info, can you say if economy is improved. Probably too early for testing.
I was planning a round Australia trip last year, well, the Covid put that on hold.
What I was aiming for was 'optimal' timing at around 2,500 RPM for the trip, mainly for economy, long distant cruising at around 110kms speed. very rarely get to 4,000RPM+ in the V8 Disco.

I was planning on modifying the distributor for this, but now considering what you have.
Keep us informed, a great thread.
Ron.

I have drawn up a new MAP for LPG. I will try it over the next few days.
It has initial timing of 18 degrees, 10 vacuum advance and 10 mechanical advance.

Top left hand corner is 18 initial + 10 vacuum = 28

Top right hand corner is 18 initial. There is no vacuum advance as this would be full throttle. = 18

Bottom left hand corner is 18 initial + 10 vacuum + 10 mechanical = 38

Bottom right hand corner is 18 initial + 10 mechanical = 28

All the mechanical advance is in by 2200rpm.

LPG MAP.jpg

Got the new LPG MAP in, took around an hour. I haven't driven it yet but it started no problem and sounds really good.

NEW LPG MAP.jpg