Help with Timing Please - MSD 8503 E-Curve

why move plug wires around?
some times TDC is not what it appears on the balancer
find tdc and mark it.
set the timing somewhere around 10-12* intial timing
adjust the carb
it may also be you have the carb adjusted wrong.
are u sure u are not 180* out.

gotta go
going to see true grit:evil:
wife is taking me out tomorrow i turn older:icon18:

I moved the wires, well, not really moved, but removed and put back on, for verification that I had the FO right and all was well.

Here's what I did just now.

First of all, too many exhaust fumes I think (even with window fans), but I think when I was checking, I actually left the vacuum hooked up. That AND...I had switched from the side vacuum port to the full manifold port (this is a Street Avenger 570), and I think I was just getting way too much vacuum.

I switched them back, and verified TDC. Side note with the GT40P's...if you don't have the body on, you can actually shine a light into the #1 plug hole and WATCH the piston to find TDC. Nice. Also verified rotor pointed to #1.

Then, I fired it back up and with dizzy and idle screw adjustments, set the initial timing to about 13 degrees.

I used the curves in the book though to give me 20 degrees total curve, which set the Switches to 4 and 5, and checked it again. Now, it shows my initial timing around 3 degrees and total at 3000rpm at about 22 degrees, so full curve of 19 degrees.

Again, this thing is ALL ELECTRONIC...so you can't really use standard logic with setting timing with it.

Anyone have experience with it that can just shed some light? I'll see if I can find Mike as well. Once I figure it out, I'll do a tutorial. They seem to be nice dizzy's, but man, I miss being able to set them easily.

Some more info:

302, SA 570, E303 cam, GT40p's.

Thanks!

I just did one. It's pretty slick once it's all set up and offers tons of timing curve options. You first need to adjust your thinking to be backwards from what we are used to. Dealing with a conventional distributor we set base timing then fiddle around with the advance mechanism until we get our desired total timing. With the E-curve you set for total timing and adjust the curve for the desired profile and base timing. In reality what happens is that the electronics within the distributor actually retard the timing from the distributor's physical position. With the rotary switches set to lock out the advance break out your timing light and clamp the distributor down when you reach your desired total timing. Now review the graphs and choose the "mechanical" and vacuum curve you want and set the dashpot switches to the corresponding numbers. Depending upon the curve selected, when you start the engine and look at your timing at idle it will be at something like we're used to, say 10 or 12 degrees even though the distributor's physical position may be at 35 or 40 degrees. Run it up to 3,000 RPM or wherever the curve you selected reaches maximum advance and you will see that are back on your total timing setpoint. The electronics within the unit are pulling timing out at low speed and bringing it back in as RPM increases. Clear as mud, right?

Good luck,
Jeff

JKleiner said:

I just did one. It's pretty slick once it's all set up and offers tons of timing curve options. You first need to adjust your thinking to be backwards from what we are used to. Dealing with a conventional distributor we set base timing then fiddle around with the advance mechanism until we get our desired total timing. With the E-curve you set for total timing and adjust the curve for the desired profile and base timing. In reality what happens is that the electronics within the distributor actually retard the timing from the distributor's physical position. With the rotary switches set to lock out the advance break out your timing light and clamp the distributor down when you reach your desired total timing. Now review the graphs and choose the "mechanical" and vacuum curve you want and set the dashpot switches to the corresponding numbers. Depending upon the curve selected, when you start the engine and look at your timing at idle it will be at something like we're used to, say 10 or 12 degrees even though the distributor's physical position may be at 35 or 40 degrees. Run it up to 3,000 RPM or wherever the curve you selected reaches maximum advance and you will see that are back on your total timing setpoint. The electronics within the unit are pulling timing out at low speed and bringing it back in as RPM increases. Clear as mud, right?

Good luck,
Jeff

Click to expand...

Thanks. I consider myself marginally intelligent, and this makes my brain hurt.

So, on the timing light on the degree indicator on the balancer, at 1100rpm, I set it to 13 degrees with NO vacuum hooked up.

Is that the right first step? If not, and if I reverse my thinking, do I set my initial timing with 1-0 and 1-0 (switches) to 34-36 (my desired total advance) instead, and then set the switches so it retards it?

I'd like to get 20-25 degrees of advance total, and as the vacuum is hooked up right now, it appears I'm getting 9-10 degrees of vacuum advance.

Looking at the curves, I had in my notes that I wanted E, which would be 1-4 and 2-5. Would that be correct as far as you know?

I like the options here, but it seems like they could have gone about the setup more conventionally.

Okay, so here's where I'm at now, maybe you can give a gentle push in the right direction.

Set the dizzy to 0 0 and then total timing to 35 degrees (with the light). I set the curve to curve E with vacuum advance of 3, so dials are 1-4 and 2-5.

Now, the initial timing is 13 degrees or so, and at 3000rpm, it maxes out at about 42 degrees on the dial. It's got a nice acceleration curve (it's on the lift, so by sound).

If I run it down to 800rpm, it is pretty violent, and smooths out a lot right at 1000rpm or so. Maybe the e cam is supposed to rattle and roll like that at those low rpm's though.

If I go with an A-D curve, maybe I'll get better idle response?

I just don't want to start flipping switches without knowing which way to go.

Thoughts?

For now take the vacuum advance out of the equation by disconnecting it and plugging the hose. The one I just did is an Ford Racing E cam 306 with GT40X heads and a 570 SA so it is similar to yours. Without going out and lifting the cap to verify which number the rotary switch is on I'm fairly certain I set it for a 20 degree advance giving a total of 32-34 all in by 3000. At idle it shows ~12 BTDC. It is not agressive but I think that is a good starting point. I will tweak the vacuum advance when we can get the car on the road at cruising speed, which is where it comes into play. We'll want to get maybe 10 degrees additional at high vacuum but have it drop as cylinder pressure rises to avoid detonation. It seems to be happy idling at just a touch over 900 RPM (as indicated on the Speedhut tach but don't know if that is dead accurate). There is some lump to the idle but it snaps up cleanly without hesitation. Out of the box the Street Avenger floats were a bit high, the idle circuit was very close (screws are probably within 1/4 turn of where they were). I think you are zeroing in on it; hope this helps!

Jeff

JKleiner said:

For now take the vacuum advance out of the equation by disconnecting it and plugging the hose. The one I just did is an Ford Racing E cam 306 with GT40X heads and a 570 SA so it is similar to yours. Without going out and lifting the cap to verify which number the rotary switch is on I'm fairly certain I set it for a 20 degree advance giving a total of 32-34 all in by 3000. At idle it shows ~12 BTDC. It is not agressive but I think that is a good starting point. I will tweak the vacuum advance when we can get the car on the road at cruising speed, which is where it comes into play. We'll want to get maybe 10 degrees additional at high vacuum but have it drop as cylinder pressure rises to avoid detonation. It seems to be happy it idling at just a touch over 900 RPM (as indicated on the Speedhut tach but don't know if that is dead accurate). There is some lump to the idle but it snaps up cleanly without hesitation. Out of the box the Street Avenger floats were a bit high, the idle circuit was very close (screws are probably within 1/4 turn of where they were). I think you are zeroing in on it; hope this helps!

Jeff

Click to expand...

Big help, thanks so much. I detailed the procedure on my blog, so hopefully people can use that as a guide to help. I don't know why the msd instructions couldn't just freakin' tell you that it's bass-ackwards from usual. They say "different."

Anyway, I'll pull and plug the vacuum and see how it runs. I'm not a huge fan of the ultra-lopey "about to die" idle, so 900 would be just about perfect I think. I'm still a bit away from any real gokarting, and 100's of hours of body work from being on the road, so time will tell.

The next time you get into that particular setup, I'd love to hear the dial settings. I have my rev limiter at 5500 right now as well.

Thanks so much, I literally wouldn't be able to build this car without this forum...awesome!

For those following this thread or reading it in the future, here's a link to the blog post where I detail the procedure. I'd love to get comments on it if I screwed anything up.

http://www.kdcobrabuild.com/2011/01/cables-timing-woes-and-exhaust-fumes/#ecurve