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Discussion Starter · #1 ·
So RCCDrew convinced me that my 6.6mpg average in the 74 440 Ramcharger (3.54 Gears, 33" tires, Eddy 1407 Carb, Stock everything else) should not be accepted and I need to tune the timing. Currently it's set to 12* initial and 38* at 2000rpm with the Vacuum Advance disconnected using a Dial Back timing light.

One thing I'd like to have, are O2 Bungs welded in with O2 sensors connected to a Wideband 02 gauge to monitor AFR, but I do not have that :(

I've watched these two video's by Unity Motorsports & David Vizard about 5 times each now and I'm coming up with an order of operations.

1. Disconnect Vacuum Advance Pod from carburetor and connect to MightyVac in Cab via vacuum line
2. Verify all vacuum ports are leak free
3. Connect Vacuum gauge to manifold tree in Intake
4. Drive truck on flat, open road at cruising RPM (I'm going to shoot for 50mph which is 1900-2000rpm for me)
5. Document Manifold Vacuum at cruising speed & RPM
6. Use MightVac to pull vacuum on the Vacuum Advance Pod until the vacuum gauge stops increasing (Document maximum achieved vacuum, corresponding RPM and Vacuum amount in MightyVac) Repeat several times to document trend.
7. Back in the driveway, tune vacuum advance pod at previously documented RPM so that vacuum advance is achieved. (this is going to be the hard part as I don't know if the existing vacuum pod will achieve what the engine needs it to)

Ultimately what this accomplishes is the same thing that modern computer controlled custom tuners are able to do with a laptop and tuning software. The other (and much more expensive option) is to use a Distributor from https://progressionignition.com/


One of the big changes I want to make with this truck, is a Holley Sniper EFI setup & corresponding Holley Hyperspark distributor, but that's a ways out and I can make changes using the above method right now with what I have.
 

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Discussion Starter · #2 ·
I found some more good reading along with the Mopar Performance guidelines and suggested #'s for setting vacuum advance.

 

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You sure you have 38 degrees at 2000rpms. What do you have @2500rpms. Or is your timing all in at 2000rpms that’s a little soon. On lifted street drive trucks 34 degrees maybe 36 @2300-2600rpms. Why late to avoid ping
 

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if you want MAX gas mileage tune - timing and Carb adjustment - use a vacuum gauge and adjust for MAX vacuum at/in all conditions [ older vehicles actually had a vacuum gauge on the dash ]
 

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Discussion Starter · #6 ·
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