Programming engine timing

[SamW]

I am working on the programming on my 3.0 V6 with GoTech and just wanted some people with experience to chimm in to help get me in the right direction. I will start with thinking through the basics and correct any thoughts I have here that are wrong. Simple weight advanced distributor with vacuum advance (I know the alfa is not like this, and my advance is un plugged, just looking at theory), if I have the idle timing set at factory specs when I plug in the advance, it will advance the idle timing by a few degrees at the same rpm, so say timing is set a 7 BTDC, with the advance plugged in it will go to 10, right? and this vacuum is pulled through through the throttle body which works opposite of normal engine vacuum and decreases with rpm, so the 10 degrees would stay or advance slower closer to idle beacuse rpm would start the weight advance mechanism but the decrease in vacuum would loose advance throught the vacuum advance, correct?

Now a few things I don'r understand, should the timing advance with engine load and RPM? should this be consistant across all rpms? should the timing curve look like the fuel curve, increase with both load and rpm? what about timing to start the engine? more or less?

Thanks for the help!

Sam

[slyalfa]

as far as know the idle wants to be very small due to smog. then ramp up very fast to say 20° or so then ramp from there to the max at max RPM
and it will need to retard some under load if it pings. so far with the S cams and S pistons I seem to only get pings at low RPM like around 1000 runing 91 (M+R)/2 gas

[SamW]

Thanks! I did a little research yesteday, I now have a map that looks like it should be decent, very conservative, I did drop the timing at loads at lower rpms, should this continue at higher rpms? Is the a reason to have less advance at very low loads, below idle, say during downshifting?

[slyalfa]

this is what I am runing right now

[SamW]

Ah! Wonderful! That helps a lot!!! Is this in your Verde? S cams? Headers?

I am guessing that 10 kPa is idle and 100 kPa is WOT?

[Little Italian]

I've read you want to retard a bit at the very top end to provide some engine braking action. Guess it provides some limit to prevent engine destruction. ????

[slyalfa]

no headers but S cams and block. I have a soft rev limit set in the VEMS so I did not do that. but in the spider where I was runing spica and only using the the VEMS for spark I did retard to 0° past 8000 RPM but that can also be risky, if too retarded it will burn that valves off. and as soon as I get some time to work on it I will now have a VEMS controled spica. I just have not had to time to put the parts in the car and try it.

and yes 100 kPa is WOT

[SamW]

Thanks! I have made adjustments to mine and it is running much better now, nothing great, but noticable, I may slowly try to work in more advance, but right now I am quite happy, thanks for the help! I will make it to the dyno soon enough!

[slyalfa]

BTW are you runing closed loop?
I found that tuning the Ve is super easy if in closed loop. drive around a bit logging
and just look at the WBO² corrections and just add or subtract that to the ve
and that is it.

[pillowmeto]

Quote:

Originally Posted by slyalfa no headers but S cams and block. I have a soft rev limit set in the VEMS so I did not do that. but in the spider where I was runing spica and only using the the VEMS for spark I did retard to 0° past 8000 RPM but that can also be risky, if too retarded it will burn that valves off. and as soon as I get some time to work on it I will now have a VEMS controled spica. I just have not had to time to put the parts in the car and try it. and yes 100 kPa is WOT