I have been doing my homework, and I can't figure this one out. Why not run a locked dizzy to give a megasquirt n' spark it's tach signal, and set it up to run direct fire on the leading plugs?? I have not seen and definite info saying that only running leading plugs loses power (i belive "within the error margin of the dyno") I also stumbled across this, which seems well thought out, and might tie into all of this:
http://www.geocities.com/cd23c/dlidfis.html
Please give me some feedback, am trying to plan how to get through all of this to get my car rollin.

 

I am currently running MS on fuel only. My dizzy is not locked but I do run direct fire. I am getting a tach signal off of my MSD 6A. Works fine for now. I just haven't gotten around to adding the ignition circuit yet.

 

Using the dizzy will never provide as good a spark as the 2nd gen ignition system. Also, although some people seem to be having problems with using the CAS, it really isn't that hard if you just directly follow what I have in the FAQ. I know that the DLIDFIS is better than just a standard dizzy... but if you already have a stock 2nd gen ignition system, KEEP IT! don't get rid of it.... it's a VERY high quality ignition system.

What I'm saying is that using the dizzy doesn't really gain you anything, and it loses you the very strong spark the 2nd gen system produces.

Finally, if you lock the dizzy, how are you controlling ignition advance? You can't use the MS to do it if you're triggering it from the coil... you'll have to have some kind of VR sensor or Hall sensor to get a signal into the MS...

 

Maybe something can be adapted using the "4 tooth wheel/2 reluctor"(whatever) setup in the electric FB distributors... I believe it would require some coding changes to the megasquirt code, but I doubt it'd be anywhere as good as a CAS signal, and even then If you're going to go to all that trouble, you might as well drop a CAS in and use FC components, anyway.

If you're going to keep the dist. use a "trick circuit" with an FC coil/ignitor setup and plugs. Then disable vac. advance, set your idle timing to about 5 degrees BTDC, mechanical advance will yield a total advance of 20 degrees or so and comes fully before 4k. I ran this with fuel only for quite some time and it worked well. That is, until my ignitor died from an as of yet undetermined cause.. but that is another story.
Honestly, like muythai says, don't use the dizzy, even with, DLIDFIS, unless you just HAVE to.(trick circuit is the exception, tho..) FC components really are that much better. (not that I am dissing Jeff20b's setup, this is just my opinion)

http://www.megasquirt.info/v22manual/rotary.htm If you haven't found it already... Also, there is a lot of good info about this in the 1st gen section.

 

Thanks for the info, I was just thinking about diferent ways around the vr conditioner circuit, as I bought a pre-assembled unit and I do not have the knowledge to modify it properly. I do have a very strong 12v background though. I did not realize that the stock FC ign system was that strong. Why do people go the trouble to put MSD on them then? Marketing victims?

 

gishgish,

If your car is running now with dizzy ignition, I'd suggest starting with a fuel-only installation. If your dizzy ignition is functioning properly the room for improvement on the ignition side is quite small anyways. Focus on getting the efi side of things functioning, and have a blast ripping around tuning, and datalogging. Then, when you get bored of tuning fuel, start collecting the knowledge and parts needed to control ignition as well. The chances of a pain-free install are much higher going this route.

 

I think this is a matter of opinion... I started with fuel and ignition and have never had a problem... it depends more on the person doing the work than anything else.

If you got a v3 board gishgish, you can modify the CAS instead of modifying the vr sensor conditioner... Just cut 2 teeth opposite each other out, and make sure you stab the CAS correctly and set up the software correctly.

I'm not sure why people put those MSD/Crane cams units on their cars... tofuball put a crane-cams unit on his car and according to him, his emissions got worse, he lost low-end torque, and his gas-mileage decreased... and I think the only thing he gained was the ability to go to 9000 rpms in first gear (he was having spark breakup in first gear when he tried to rev that high... no problem in any other gear). I think a lot of people use them to avoid that high-rev spark break-up.. Last week tofuball's car wouldn't even start on the crane-cams unit, so he is back to using the standard 2nd gen coil and ignitor.

Finally gishgish, if you ever want to use the MS to control ignition instead of using a dizzy, you'll need to modify it anyway, but I've documented how in the FAQ, and it's not that hard.