Further adding to the "nauseam", here is what a decent advance curve looks like for a Nuttered 258. Disregard the pink lines, since that is with the vac advance connected and really has no bearing on performance under load. The centrifugal curve is what is important for this discussion.
Note, this is with a pre-computer (1981 or older) Motorcraft distributor, with an 18* advance head. I also spent considerable time fiddling with different advance spring combinations until I found a setup that I was happy with.
The first graph is where I started, the second is where I ended up. I never did get the centrifugal advance to kick in as quickly as I wanted it to, but these changes made a huge difference in the performance of my ol' chugger.
I used this Chinese made Multi Spark Capacitive discharge from REDLINE.
My #1 plug wire fell off as I had a timing light hooked up to a spring on the plug and wire.
This thing laid out a 1" inch arc, bright white, and they want me to gap the plug at .045". Whew..
Here is what they say about it.
REDLINE, Digital 6 Series
Multi-Spark “CD” Ignition Box with Coil – “KIT”
• This Capacitive Discharge Ignition Box delivers 525 volts to the coil and the coil delivers up to 135mJ of spark energy for complete combustion burning.
• With this “HUGE” amount of sparkenergy (135mJ), this unit features multi-sparks in each cylinder from idle to 2400RPM, with confidence in a more complete combustion burning resulting in maximum efficiency and power.
• Easily adjust the rotary dial-switches for:
1. Number of cylinders 4, 6, or 8 cylinderengines.
2. Select the rev limiter in 100 RPM increments to 9900 RPM.
• The efficient digital circuitry in this Ignition Box only draws 0.7 Amps per1000RPM of engine speed.
• All loom wires enter the Ignition Box on one end using a sealed Delphi Metri-Packconnector eliminating corrosion, dirt and oil from the wire connections.
Ok, I'll reset it to 10* @ 600-700 rpm. I think it's already been nuttered. Shawn, I misread your vac advice...it was already on manifold vac and I moved it to the vac port on the carb. I'll move that back.
Also, a few items I discovered (and overlooked!!!)...the carb is an EMPI, not Weber like I thought. (Ok, you guys can let me have it...)
Also the engine is a '85 on this '83 body.
Uptillnow, I started at Shawn's original Weber thread, but I was confused because I had both carb screws all the way in. At least I have the screws to the starting point, and it will run, somewhat :-)
Can you give me a quick tutorial on the 7* dizzy vs the pre-81? Is 7 the max range of adjustment?
In the pic I posted above, you can see the advance slots in the advance head. Those slots dictate the maximum amount of centrifugal advance. The stock computer-controlled Motorcraft dizzy only had about 7* of centrifugal advance (a much skinnier slot). The pre-computer dizzys have up to 18* advance, like the one in the pic.
Without the computer, your engine really needs a dizzy with the larger advance slot.
NAPA sells them. Be sure you can see the correct advance slot labels thru the little peep hole in the top of the dizzy. My NAPA had to pull 3 of them before we found one with the correct. head.
The 13R indicates you have the correct head. If you spin the dizzy's shaft, you should see the 18R stamp.
What this doesn't tell you is if the head is set to the 13R or the 18R slot. The dizzy only uses one of the slots. See the tab inside of the 18R slot in my earlier picture? You'll have to pull the top plate of the dizzy to determine which slot your dizzy is using.
If it's set to the 13R slot, flip the head over to the 18R slot.
Ok, got the dizzy swapped over to 18*, warmed up, vac off, 600 rpm (had to tip some throttle in to keep it there) timing set to 10*.
Pretty much same scenario. 1.5 in on the idle speed, 2.5 out on the mix. Still running rich and rough with puffing black smoke.
Low idle, it barely runs, or dies. If I keep a little throttle on to maintain 500-750 rpm, and I turn the mix screw in, it gets a little better, but I can still crank it in all the way and as soon as I'm off throttle, it'll die. Also tried turning it out but it just got a lot rougher like it was flooding.
When I took the carb off and turned the idle speed in till just before the enriching hole, it was right at 1.5 turns in. I made sure of that.