I read a post that if you have better voltage going to the coil you will improve mileage. The post described changing the wiring and connectors from the coil back. I have done that.
I drive 120 miles a day and am averaging 20 mpg. I have about 10,000 miles on a recent SL6 rebuild with mild mods for more torque and mileage per Doctor Dodge. The engine has alot more useable power down low and alot of fun to drive. I cruise between 2000 rpm and 2600 (50 to 70 mph) The Doctor is right on! I am looking forward to the Super Six and Dutra Dual conversion.

What should the voltage be at the positive coil terminal and or at the bottom of the dual ballast resistor for the ignition to work at it's optimum?

My plugs are coated with a beige to a light cinnamon colored dust/deposits. I really can't get them to burn any cleaner to where they stay a little whiter like they do in my 69 440. Using Cenex regular for gas. The SL6 is 9.5 to 1 the 440 is 10 to 1. I also can't get the SL6 to ping. I have about 55 degrees total advance. 10 degrees static, 22 degrees mechanical and 22 degrees vacuum.

I measured the voltage last night after I got home and the top of the dual ballast is running 13.84 volts average and the bottom of the ballast and the coil positive terminal show 5.20 volts. This seems kind of low, but it is being measured at an idle after driving 60 miles.

I am also using a new orange ECU an MSD Blaster 2 coil and 3027 Champion plugs gapped at .035, 8mm wires, Blue Streak rotor and cap. Just ordered the NGK UR4GP's per the recent posts.

Should the voltage be higher at the coil? If so, what should it be?

If I change over to the HEI set up, what would the voltage be at the coil?
Will the HEI set up help provide better mileage?

Suggestions would be appreciated since gas just reached 3.26 a gallon for regular here in the Puget Sound.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

That is not necessarily true.
H'mmm...can you show us this post you read?
Then you're doing pretty well!
That is going to vary with factors including engine RPM and the specific control box in use. Lower RPM = lower voltage downstream of the ballast resistor. Higher RPM = higher voltage downstream of the ballast resistor.
I have been thoroughly unimpressed with the poor quality of the Mopar ECUs (orange, chrome, or whatever other color) for the last several years. You probably already know I recommend the HEI upgrade.
I've had good results with this coil
The Blue Streak cap is excellent, but their rotor has an extra-short tip. Go order a NAPA Echlin long-tip rotor # MO-3000, then once you've put in the HEI, open up your plug gap to 0.045". Whose plug wires are you using?
That's a platinum plug, not necessary for your application; a regular UR4 would do just fine, but the GPs will work well, too.

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Here is the post.........

Sam Powell
EFI Slant 6


Joined: 04 Jun 2006
Posts: 431
Location: Gaithersburg MD

Post subject: (Mon Apr 16, 2007 4:54 am) Reply with quote
This is one off my "standard" replies. There could be many problems there, but something is wrong for sure. Your choke could be stuck, or the power valve could be open all the time. Your timing could be way retarded, or your vacuum advance not working. That 18 MPG figure is pretty typical, but in the 20's is not uncommon. I have gotten mid 20's with a stock duster in the past, just well tuned.

One commonly ovelooked component is the ignition wires from the alternator clear through the ampmeter, ignition switch, and then to the battary and on to the ballast resister. On a car that old the connections are going to be pretty crusty, and will loose power and efficiency there. Measure the voltage at the battery while it is running, and measure the high side of the ballast resistor. You should see less than .5 volts drop. My Dart, when it was stock went from 13MPG to 18 MPG by changing the connectors on the blue wires under the hood and dash. This meant clipping off the old one, and soldering on a new one. I cleaned up the bulkhead connector too. Just start at the alternator wires, and follow them along to the voltage regulator and bulkhead connector, and replace each connector as you come to it. It's a pretty cheap thing to do, with very positive results. If the ampmeter is bad, and you are loosing voltage there, you must either replace it, or bypass it and install a seperate volt meter to keep track of the charging system. I like the volt meter system better anyway. Good luck. Keep that car going.

Wider tires do cost you mileage, but my Corvette got 22MPG average with 285's on the back. It should be possible to get good mileage with those tires.
Sam

On the wires..........
I forget which brand, they are a heavy duty 8mm Blue Silicone wire with a 6 sided hex molded at the plug, from Summit.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Oh, OK, you're not talking about changing the wiring, you're talking about making sure the wires and connectors are in good shape. Yep, that's advisable.

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Too many people who were born on third base actually believe they've hit a triple.