2.2 SE advance curve - Aldon Amethyst

[Pjr]

I feel in great danger of asking a question for which the answer is already in a post somewhere, but I cant find the actual information I am looking for.....so.....

I have just ordered an Aldon Amethyst for my 86my SE. I can see the merits in full crank-pulley driven ignition systems and i think they are the ultimate, but at the same time i think this unit should give me most of the benefit (although fire risk remains ) at a low price and with easy fitment.

Anyway, although the service manual gives a few points from which to plot an advance curve, there is not much detail. Has anyone used this system and could share the map? I have seen the detailed posts from people using more sophisticated systems but im not sure that i can faithfully translate the data across to this system.....at least not confidently.

I will report back after the weekend once the device is fitted........

[richardw]

I'll be very interested in how you get on...

For a timing map, tonypoll has an ignition only DTA system on his Excel SE and has published his setup following rolling road tuning here: http://www.lotusexcel.net/phpbb/viewtop ... dta#p56675

I'm not sure of the setup parameters on the Amethyst but I'd imagine that Aldon could assist with any questions about translating the map.

Good luck, Richard

[Pjr]

Hi Richard, thanks for the encouragement. I saw Tonys post, but im not sure what of that data i would enter into the Amethyst. Amethyst seems a lot more basic and i think it just gives you an adjustable 2d curve which the vacuum sensor then modifies further. I dont belive it allows the creation of a 3d graphic map or anything that sophisticated - if im wrong about that Ill correct this post once ive played with it.

The data i need must be in Tonys post, but Im just not sure what I should extract!

Cheers

Phil

[richardw]

Hi Richard, thanks for the encouragement. I saw Tonys post, but im not sure what of that data i would enter into the Amethyst. Amethyst seems a lot more basic and i think it just gives you an adjustable 2d curve which the vacuum sensor then modifies further. I dont belive it allows the creation of a 3d graphic map or anything that sophisticated - if im wrong about that Ill correct this post once ive played with it.

The data i need must be in Tonys post, but Im just not sure what I should extract!

Cheers

Phil

Hi Phil,

The table you need to look at is the 'basic ignition map'. I believe I'm right in saying that the timings related to centrifugal advance occur under maximum throttle loads (= minimum vacuum) so the final column in the table show these. The rest of the table effectively shows the impact of vacuum advance under lighter throttle loads, although there is no easy way to correlate vacuum advance to throttle load. I guess the Aldon system will do that itself, however - maybe you just need to set max vacuum advance and it does the rest for you.

Richard

[Pjr]

Pleased to say that the Amethyst has arrived. Interestingly, the glossy piece of paper in the box shows a 3d map like Tonys, but i dont think the software actually has the facility to display the map in that way - time will tell.

The instructions look fairly simple:
Green wire to Distributor output
Yellow to Coil -ve
Red to Switched +ve
Thick black to Earth
And finally a thin black wire that allows you to switch between maps on the go.

I have two things on my mind though:

1st, at a glance my distibutor has two wires emerging from it which go to the ab14. Which connects to the Amethyst single wire and what happens to the spare one? I imagine it goes to earth, but at the moment its not entirely clear!

2nd i have read elsewhere about getting a "clean" switched positive for electronic ignitions. Can I just reuse the positive to the AB14 (solid white wire i think) or is there a better place to take the feed from?

Hopefully I can pick up some vacuum hose tomorrow and start installation this weekend. I will try to take a few photos for posterity.

Phil

[Pjr]

Ive had a bit of a frustratingday today. After a nice start at Paul Matty to collect a steering u/j and drool over the beautiful cars i went over to Aldon to get an Ignitor so that I could start the installation. Aldon didnt have one in stock and they could not sell me a new distributor with the parts installed as they have a two week waiting list. however, they were very nice and gave me two replacement springs so that I could restore my distributor if I wished.

I then went to Powerspark at Bromsgarve and bought a bod-standard hall-effect trigger. After a bit of getting lost in the W.mids i was home by lunch.

I installed the hall sensor, which was not a perfect fit despite being for the 45d4 distributor, but it was ok. I then wired up the Amethyst but could not get it to recognise the static timing position. Apparently, w/o points, that can happen. Roger from Aldon talked me through the intpstallation and it was all to book, but we could not get it to work. Roger did wonder if there was an issue with that unit.

As the rain began and after 6 hrs of trying everything i uninstalled the Amethyst and rebuilt the distributor and reset the timing. Ironically, the car is going very well now - perhaps the advance weights were a bit sticky before or the mid-strength springs Aldon gave me allow more advance at speed.

I know that sometimes things go this way, but as I dont know if its the sensor or the amethyst its all being returned to the supplier (powerspark) who will no doubt take it up with Aldon.

Its a great idea and the Amethsyt seemed well made. The idea of 3d ignition for under £200 is very attractive. i think i have either made some error (although its only 4 wires that need to be connected) that Roger could not detect over the phone, or the unit (or sensor) has a fault. But for now at least, I have to report a failure to advance......

As the electrics absorbed all of my time I didnt get a chance to change the lower steering uj. However, a quick play with that revealed a substantial amount of slop. I have gone for the genuine Lotus replacement (looked nicer than the excahnge one) and I will follow the ideas of others here to cover it with an inner tube section.

Hope you all hade better success with your Lotus fettling this w/e. Happy tinkering.

Phil