ignition advance SC with MS

[trond]

I have been a very happy Megasquirt user since my car was converted to tbitz in 2011 in one busy afternoon at Jamie Novaks in Austin (hi Jamie and thanks again !)
My distributor was worn and I since went distributorless with MSII and EDIS ignition and the system has worked flawless from day one. Not one day of downtime in 5 years and 32000 miles !

While fuelling is easy to get right (Tunerstudio and wideband lamda), even on the street, ignition is another thing. I tried on a chassis dyno, but prior to installing TPS it just was not easy with map only.

So I have been experimenting with ignition maps on the road which obviously is not to be recommended.....

I am lucky enough to have a friend with the exact same engine in his car(all stock CIS and ignition and all). Driving his car I always found his car to be quicker than mine. Seat of the pants quicker that is. Sweeter engine note and rev happy, as opposed to mine.... With my car I always thought 'this car is not really very fast at all', while with his car I always wondered how could a mere 3 liter stock car be so good...

Given that fuelling is hard to get wrong with MS and wideband, I came to the conclusion that ignition is the only real difference. And the significant difference was he most likely had less advance than I. So I started reducing ignition advance and found to my surprise that the engine seems happier with less advance. I am now down from 32 degrees, to 26 degrees and finally a few days ago 21 degrees at WOT. Which is the best setting until now. I am 'all in' from 2000 rpms and more or less 20/21 all the way to stock redline. I am aware this is not by the book but I just wanted to check it out. At cruise I still run around 40 degrees which seems to work fine and good fuel economy, but the slightly hard engine note from before at higher loads is all about gone ! And the engine is without any doubt more revhappy. Seat of pants for what its worth is positive. I am aware all of this is not quantified in any way and I would be be very cautious using my anecdote for anything. See it more an question to the forum; could it be true or not that the 3 liter 9.3 CR likes significantly less ignition advance than what is commonly referred to on the web ? Or do I have something upside/down ?

[wiggle_puppy]

In your profile you say that your car is an ex-California car...it sounds like you have a U.S. market car while your friend may very well have an ROW car. Moreover you don't mention the year of your friend's car.

Do you know for sure that your engines are the same in all aspects? Large port vs. small port heads and CIS, and U.S. vs. ROW compression ratio?

Forgive me if you already accounted for those differences as I don't have any input on ignition advance. As the owner of a 1982 SC I'm interested to hear people chime in about the ignition settings.

[trond]

both cars are 1980 model SCs imported from the US, with small port CIS and 9.3 CR. SSIs and 2-1 mufflers

[Tippy]

If 21 is good, sounds like your trigger offset is off or moved.

Can check with a timing light.

[trond]

I did chech trigger offset when I set it up but will re-check in the morning. 21 sounds like something could be off

[trond]

stock distributor advances 20 degrees.... According to the curve total advance will be at 21 degrees from 2400 rpm to 5000 rpm and max out at 25 degrees@6200

Also I verified trigger offset and it was accurate....