Lotus Elan

Elan Sprint 123 Bluetooth Distributor for Weber engine

PostPost by: dpchamp87 » Fri Jun 26, 2020 8:33 pm

Has anyone got a good ignition map they could share? The one 123 suggest is hopeless.

Thanks in advance

David
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PostPost by: tdskip » Sat Jun 27, 2020 11:47 am

Hi David - I bought but have not actually installed or used a 123 for my GTV. Can't you modify the suggested one easily from the app? I may well be off base with that suggestion but seemed worth offering up.
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PostPost by: nmauduit » Sat Jun 27, 2020 1:26 pm

checking notes taken during a dyno session I have retained

1k 12°
1.4k 18°
2k 25°
3.5k 32°
5k 34°
6.8k 34°
8k 19° (sort of safety precaution in case the rev limiter does not work somehow)
You may reduce the total advance if you are unsure of the octane level of your favorite fuel, or depending on your actual tune and goals etc. I use NGK BP6ES plugs on the road, 7 for track days.

also have implemented some kind of idle stabilization at 1k rpm with something like (don't have the exact value at hand but you'll get the idea)
0k 0°
0.5k 15°

std disclaimer : no warranty of any sort, expressed or implied...
Last edited by nmauduit on Sat Jun 27, 2020 2:54 pm, edited 1 time in total.
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PostPost by: h20hamelan » Sat Jun 27, 2020 2:25 pm

dpchamp87 wrote:Has anyone got a good ignition map they could share? The one 123 suggest is hopeless. David


Have you got it to start and run?
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PostPost by: awatkins » Sat Jun 27, 2020 4:47 pm

I’m curious; what map does 123 suggest?
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PostPost by: nmauduit » Sat Jun 27, 2020 5:38 pm

awatkins wrote:I’m curious; what map does 123 suggest?


I think it's the same dizzy for Kent crossflow engines, so it could be for that as a primary application...
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PostPost by: awatkins » Sat Jun 27, 2020 5:45 pm

Sorry, what I meant was, what advance curve as in list of “x degrees at y rpm” do they recommend? And for that matter, what makes it “hopeless?”
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PostPost by: dpchamp87 » Sat Jun 27, 2020 6:57 pm

Thanks for the replies. I have got the car to start and run. It starts and ticks over ok and on full throttle it is fine. However the throttle response is just nor good at all.

The 123 recommended map is as follows:

500 = 12
1000 = 17.6
2500 = 28.7
4500 = 32.8
6500 = 36
8000 = 36

Using those settings the car felt like it had too much total advance and on full throttle it did not sound smooth. I run VP C9 96 R+M/2 in the car. The motor is standard big valve Weber TC with only a slightly higher compression.

I them modified the curve to be:

500 12
1000 = 17.6
2500 = 25
4500 = 28
6500 = 30
7000 = 30

When we dyno'd the engine after it was built we used 30 degrees max advance.

I can just keep playing with it but I was hoping someone else had already done so!
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PostPost by: awatkins » Sat Jun 27, 2020 7:06 pm

For what its worth, this topic
viewtopic.php?f=38&t=1996
does a good job of documenting the various factory curves.
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PostPost by: awatkins » Sat Jun 27, 2020 7:08 pm

But note well the confusion over crank vs. distributor degrees. You have to read all the way to the end to get at the properly documented curves.
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PostPost by: dpchamp87 » Sat Jun 27, 2020 8:32 pm

For what its worth, this topic
viewtopic.php?f=38&t=1996
does a good job of documenting the various factory curves.

Excellent; thanks for this info. I presume the right hand table applies to the Sprint engine on Webers and that the numbers have to be +12 for the starting static advance.
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PostPost by: TeeJay » Thu Sep 17, 2020 9:04 am

The problem I had was a slight misfire when going from idle to 2000 RPM, the car ran great at higher revs. Following a lot of research and test runs, I concluded that the problem was probably the spring and balance weights in the distributor.

I could have spent approx £240 and sent my Distributor for a complete overhaul to “Distributor Doctor”, but concluded to keep my original and invest in one from 123 Ignition at £399 + £12 postage.
I purchased the Bluetooth model 123/tune +4-A-V-F, along with a Pertronix Flame Thrower 1.5 Ohm coil and Silicon/carbon leads.

The fun was selecting which advance curve to use!!

My engine has cams with single groove so a “C” type cam and so my first curve was from Miles Wilkins book, for the above cam with Webber carbs.

1) Settings for “C” Type cam including 10 degrees for static
C Type Cam 10 degrees.jpg and



The result was terrible, right up to 4000 RPM. This being my current max for running in the engine. I was surprised by this result.

Finally I found this thread and I tried those listed by “nmauduit”
Wow, what a difference, Thank you “nmauduit” for your contribution.

2) Settings from “nmauduit” adjusted for my engine, including 12 degrees for static.
My Settings C cam but 12 degrees.jpg and


I can now “fine tune” this curve by driving the car while the passenger presses the “Tune” button. Each press will reduce or increase the advance curve in increments of 1 degree to see if there is any improvement, on any of the curve points, on what is already a good running engine.

3) Dashboard with Tune button.
Dashboardx123tuneplus.jpg and


4) For information I have added the Curve settings for the D Type cam with 12 for static.
D Type Cam 12 Degrees.jpg and


I have edited the above on 1Nov 2020, to add clarity to correct some information:-

a) All my curves are for Weber carburettors and Lucas Distributor No 41189A.
Also for reference to Miles Wilkins Lotus Twin Cam Engine Book, the C type cam has 10 degrees from 0 to 2000 RPM and the D type has 12 degrees 0 to 2000 RPM. From this it can be seen that the mechanical advance balance weight has an advance of 14 degrees.
b) As my engine has only completed 500 mile since rebuild with many new parts including a +0.060 inch oversize with new pistons, I am limited to 3000 RPM with latterly the occasional 4000 RPM. So curve settings past this cannot be established at present.
Last edited by TeeJay on Sun Nov 01, 2020 3:55 pm, edited 1 time in total.
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PostPost by: au-yt » Thu Sep 17, 2020 11:21 am

This thread sparked an interest, as I have an 85 Caterham 7 fitted with Twin Cam, It has a BRM spec head 10.9 comp and what I believe are D type cams, no groves. 83.5 bore. The jetting is similar to a big valve,
I fitted a 123dizzy with an as delivered map, I have also wondered if it is pinging but it’s hard to determine as it does have any indication on the plugs, I know what the sound is but it’s hard to decide over the sound of the carbs and the exhaust.
Following on from the discussion the map my need a tweet.
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PostPost by: Andy8421 » Thu Sep 17, 2020 11:36 am

TeeJay wrote:The problem I had was a slight misfire when going from idle to 2000 RPM, the car ran great at higher revs. Following a lot of research and test runs, I concluded that the problem was probably the spring and balance weights in the distributor.

I could have spent approx £240 and sent my Distributor for a complete overhaul to “Distributor Doctor”, but concluded to keep my original and invest in one from 123 Ignition at £399 + £12 postage.
I purchased the Bluetooth model 123/tune +4-A-V-F, along with a Pertronix Flame Thrower 1.5 Ohm coil and Silicon/carbon leads.

Had no problems with the installation and setting static to 10 degrees BTDC that was straight forward.

The fun was selecting which advance curve to use!!

My engine has cams with single groove so a “C” type cam and so my first curve was from Miles Wilkins book, for the above cam with Webber carbs.

1) Settings for “C” cam
C Cam.x123tuneplus.jpg


The result was terrible, right up to 4000 RPM. This being my current max for running in the engine. I was surprised by this result.

I then tried the built in default, which was certainly better, but not correct.

2) Settings: - Default.
Default.x123tuneplus.jpg


Finally I found this thread and I tried those listed by “nmauduit”
Wow, what a difference, Thank you “nmauduit” for your contribution.

3) Settings “nmauduit”
nmauduit 123tuneplus.jpg


I can now “fine tune” this curve by driving the car while the passenger presses the “Tune” button. Each press will reduce or increase the advance curve in increments of 1 degree to see if there is any improvement, on any of the curve points, on what is already a good running engine.

4) Dashboard with Tune button.
Dashboardx123tuneplus.jpg


Are the advance numbers displayed on the app just distributor advance (in crankshaft degrees), or does it also include static?
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PostPost by: nmauduit » Thu Sep 17, 2020 1:51 pm

Andy8421 wrote:
Are the advance numbers displayed on the app just distributor advance (in crankshaft degrees), or does it also include static?


the advance value displayed is intrinsic of the distributor, and in crankshaft advance degrees : if you set the dizzy so that it has its zero at zero crankshaft (which I do for convenience, and which is relatively easy to double check via piston 1 if need be), then all values are actual advance values. If you set it at x degrees advance, then you need to add x degrees crankshaft to each value. There is a led witness light that indicates the zero reference for the dizzy, I try to set it carefully as it will be the basis of all subsequent dizzy timing operation (e.g. turning the dizzy 1° when reinstalling it on the block will add or subtract 2° crankshaft to the whole curve).
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