How much time have you spent on tuning the Spark table?

[BigBlockMopar]

Just kinda wondering how much time the average MS user has spent on getting his timing tuned in well enough so the engine runs good in pretty much all its load/rpm ranges?

Personally, I'm running Ignition only for now, but every since I've installed the MS3x in my car, I've been tweaking the ignition table on a daily/few days basis.
Only in the last month or two I tend to think I've achieved a fairly tuned overall table and only do some small tweaks every now and then.
My 'tuning' relates to street-only alterations, modifying of the timing map and trying to improve 'flat spots' in the engine's performance throughout the ranges.

[Yves]

I wonder how you can ever get your ignition tuned on the street.

[BigBlockMopar]

Spot-on tuning won't be easily possible in 'all' map-areas ofcourse, but uptil now my Butt-dyno has done a nice job at improving overal engine-performance from the day I installed the MS3 (mainly low/mid-rpm torque, because that's what counts on the street).

I always try to tune for the highest vacuum at steady cruising speeds, and torque'yest power during light/mid throttle accelerations.
The engine in my car is a low compression ratio, mid '80s 'smog' V8, to which I can now usually notice a difference of a 2-3 degrees change in timing.

Of course, spending a good day on a Eddy brake-dyno would way quicker in achieving a good tune.

[DaveEFI]

Have you got the specs for the original dizzy? Is so, it's worth drawing out the advance curve using those on graph paper or a computer equivalent and transferring those numbers into an MS table. (because the curve isn't usually a single straight line, it should be closer than interpolating from just a couple of points) The all out advance figures are likely to be about right if the engine is standard, and using similar fuel.

Using that as a starting point, you can experiment with different settings at various speeds and loads.

[billr]

Yeah, that's what I did. My engine (NA BBC) is a well-known design with plenty of info on what spark advance works pretty well at WOT. I have only fiddled with idle timing, trying to get a decent idle. As far as mid-range, I don't care. There is always plenty of power, no matter what gear it is in.

[gtmdriver]

Me too.

In the absence of any other information my spark table basically replicates the advance curve and vac advance adjustment of the original VW Beetle distributor. I have no doubt that it could be greatly improved though which is why I intend to get it on a rolling road asap.

[Yves]

You need a load holding dyno to do this.

Personally I do not like the idea of these. Most of the time the rolls are pretty small and they place a large load on the tire as the contact patch is really small. The operators usually really pull down the car onto the rolls to ensure there is enough contact patch to create enough friction. As this distorts the tire and heats it up greatly, you stand a chance that the tire blows. Not exactly a pretty sight when that happens.

[BigBlockMopar]

I've had my car on a chassis dyno, but with the Eddy-current brakes directly mounted to the rear axles.
This prevents said tire-issues. Although with a measily 170 rwHP I doubt my car is capable of causing 'tire-shredding' situations on a dyno
Unfortunatly I didn't have my current new exhaust system and MSX3 installed at the time, to see what improvements I've made with this.

[Yves]

I agree those are the best, but they run pretty thin around here.

[fntwisted1]

I took my base dizzy curve and spread it out a few hundred rpms for safety. then put it on the dyno for about an hour. got it pretty good pretty fast.