Creating ignition table from engine spec.

This forum is for discussing ignition setup, tuning, and troubleshooting for MS-II. Click these links for info on GM's HEI, EDIS, direct coil control, others.
Forum rules
Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.

If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.

If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days

The full forum rules are here: Forum Rules, be sure to read them all regularly.
Post Reply
peei
MegaSquirt Newbie
Posts: 7
Joined: Tue Mar 01, 2011 10:54 pm

Creating ignition table from engine spec.

Post by peei »

I'm trying to create a ignition table using the advance/retard from the engine specifications.
I have a NA engine (m110) in a MB280 SL which I converted to a MS2 v3 system controlling both fuel and ignition.
I'm not really sure how I should interpret the timing spec for the engine.
Does the "vacuum off" be the same as at WOT?
Could someone please enlighten me how to interpret the given values.
Using the data below should it be something like this or ???

max load(WOT) : 1500rpm/28° ... 3000rpm/34° 4500rpm /36°-40°
..
min load (idling) 850rpm/ 12°BTDC ... 3000rpm/24°(10°less than at WOT due to retard idling)

Firing order & idling speed 1‑5‑3‑6‑2‑4; 750/850 r.p.m.
601. Ignition timing –starter speed 12°BTDC <----------- This must be no load and idling
601a. (Vac. off)‑ 4500 r.p.m 34°BTDC <----------- Is this at max load (WOT)
606. Centrif. adv. at 1500 r.p.m. 28° <----------- min or max load ?
607. Centrif. adv. at 3000 r.p.m. 34° <----------- min or max load ?
608. Vacuum retard idling 10° ± 2° <----------- difference between min /max load ?
609. Vacuum advance at 4500 10° ± 2° (total 36°/40°) <----------- Is this at max load (WOT)?
kind regards... Peter
trakkies
Super Squirter
Posts: 1162
Joined: Tue Dec 30, 2008 3:06 am
Location: SW London, UK

Re: Creating ignition table from engine spec.

Post by trakkies »

How the vacuum advance effects the curve on a dizzy engine is likely different to how you'd set that up in MS - as a dizzy vacuum take-off is usually above the throttle so it will vary differently from the MS readings which are normally taken from the plenum.
Dave P, London UK.
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
peei
MegaSquirt Newbie
Posts: 7
Joined: Tue Mar 01, 2011 10:54 pm

Re: Creating ignition table from engine spec.

Post by peei »

I understand that it's hard to translate the old settings to a new map but I only need a hint from where I can start fine tune from, this is how I think it should look like (due to several examples I found on the net).
At WOT-> rich mix ->quick burn of fuel, less advance than at lower load.
At cruize -> lean mix -> slower burn -> more advance.
I've tried to keep the advance at WOT the same as the old settings, 28°/1500 rpm, 34°/3000 rpm and 36°/4500 rpm.
Please correct me if I'm totally wrong here...

Image
kind regards... Peter
Post Reply