Recently I asked Lou about making a 3d (rpm on one axis, vacuum on other, advance in middle) for my edis setup. I wanted to post his response here for all to see
The motor is a basic build, stock cam, 30 over, clifford intake, headers soon to become dual dutra duals, 1.70/1.44 valves and some mediocre headwork.

This is the map I came up with


I'm not looking for max performance yet, I want a good point to start with, something safe for driving without too much worry. Thoughts welcome.

Thanks for posting that. I assume with a forced induction set up, the bottom half would more or less mirror the upper half, dropping out timing as prssure and RPM build.

I have to confess, I don;t understand the 3D aspect. This chart still looks like a two axis graph to me. You are the second person recently to use the term 3-d graph regarding spark mapping, and I haven't conceptualized it yet.

Sam

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I believe 3d graphing was part of my high school math/physics curriculae (in 1970) .

Conceptualizing it is very necessary to using your system. Im sure you use a kind of 3 D mapping in music. I use it in a different way in my profession.

I think of spark/fuel/MAP graphing like a large square sheet ....say 12 x 12ft .. with a person holding each side. Each person represents a value (can I be MAP again?) . By raising or lowering their arms each person can change their value on the graph......and in relation to the other values.

This graph becomes more enlightening as each value changes in relation to the others quickly (we knew this game would get silly) .....you start to see ripples or swells or bulges in the sheet as the values flap their arms wildly.
When MAP value changes quickly Fuel and Advance values must respond quickly to dampen those swings and keep the sheet as level as possible.

Parachute game.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I have no idea what would happen under boost.

The megasquirt tuning program can translate to a 3d graph if its easier for some to visualize.

I just wanted to make sure I had the right shape and didn't do anything silly. This is a bit more detailed then just turning the distributor to adjust timing, and I'm a virgin when it comes to it almost no idea what I'm doing....

Sandy, I get the 3-d thing now. My tuning software has the cabaility of doing that as well. I am pretty sure you can tune from that view also. Thanks.
Sam

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Pierre, I am so glad you confessed your lack of confidence here. I do this all the time, and feel like a real nerd in the process, but I don;t see how you can learn unless you express a lack of knowledge, and uncertainty. If you try and BS an image of expertise, then you will short circuit some possible helpfull comments.

I am exactly where you are on this tuning thing. I feel like a rank amatuer, who is eager to learn from others, and from experience. The map gives you such flexibility, but it is a two edged sword. While you can get it exactly right, there is also the possibility that you can get it REALLY wrong. I have kind of decided that it is best to take your time, and make little changes in only one thing at a time, and live with the results for a bit, and then change things a bit again.

Let's try to keep a dialogue going here on this subject. It really is an EFI topic, but the idea of timing is one all car guys have kicked around for years, and I dont; want to miss any relevant input by posting this dicussion in the EFI section. That is why I started it here instead.
Sam

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Usually, the values keep going the same way: If it changes by 1 degree for every 10 kPa of vacuum, for example, you'll pull 1 degree for every kPa in the boost area. For the combustion chamber, boost and vacuum are two sides of the same coin.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Pierre,

I like your "initially safe" table. The car should run fine with those values and you can tweak from there. You will find that adding 5-15 deg of advance in the lower MAP value side (lower half) of your table will get you better economy.

Nice work and let us know how you progress.

Lou

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Home of Slant6-powered fun machines since 1988

I'm not really interested right now is doing an EFI system, perhaps later. However, someone recently mentioned that Megasquirt can be used to control timing. Now that intrigues me. It seems to me that such a system would be infinitely easier to tune and tweak than the traditional mechanical/vacuum system. How does that work and what needs to be done to/with the distributor. I have to be honest, the idea of tuning with a laptop computer instead of fiddling with springs appeals to me a lot.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I have not looked into it, but you might look at the MSD spark/timing control box. I don;t know what kind of timing control it has, but I know it has some. Maybe do a google serch, and see if you can find a stand alone spark map program. If it can be done, maybe someone has thought of it already, and either has a DYI article or a product out there. Go on the Mega Squirt web site and see if anyone has posted on this subject. You might register, and ask your own question there about this.
Sam

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dakight - go to http://www.megamanual.com/v22manual/mtabcon.htm scroll down to the Megasquirt-II section and it gives you all options for timing. Depending on how the unit is assembled, there are PLENTY of ways if you want to keep the distributor - you can take the distributor pickup (wether points or electronic) direct to MS, you can take it to HEI module then to MS, etc. The MS output can drive a coil directly (but then you have to fuss with dwell) or it can drive MSD 6a box, or HEI module. Options are plentiful.

If you want cheaper, check out the http://www.autosportlabs.com/ computer - this is strictly ford EDIS system only, no fuel just ignition. Cheaper too. I think this setup is fairly new, I haven't read too much about it. But I can tell you the MS has been proven in 10's, if not 100's of thousands of installs.

Lou - thanks for the feedback. I should have the thing running in the next few days (hopefully!)

I am running a Megasquirt V2.2 with a HEI-7 module and a Lean Burn distributor, but there are several other options. I wrote an article summarizing how to put Megasquirt on Mopar ignitions recently. The Lean Burn distributor is the easiest way to go. You can also lock out the timing in a stock mechanical advance distributor (I haven't tried that myself) or use an MSD Flying Magnet trigger wheel. There are some other, more complicated possibilities, like putting a missing tooth trigger wheel on the crank pulley, EDIS conversions, or even building a coil-on-plug ignition system, but these are strictly optional.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair