Despite reading many interweb admonishments to the contrary, mostly dealing with the unsatisfactory application of a 2 barrel carburetor to a one barrel manifold (long, poor distribution, lean front and rear plugs with rich center plugs, missing, lagging, etc.) I've just not seen any of the detrimental impacts I was warned about. To the contrary, tuning the Weber DGEV is not difficult, just different. The possibilities for tuning and tweaking seem endless. I have great drivability and fuel mileage.
Speaking of which, the last tank was mostly highway and netted 17.83 mpg on 87 Octane with good power and performance. I've since rejetted the primary main even leaner to a 130 jet and believe I've achieved a maximum lean or lean best condition off idle and into most of the driving range. On the 130 main jet I've run this tank nearly out primarily around town with a good bit more stop and go than the last tank. It would appear that on refill in a day or so, I'll be looking at fuel mileage again in the 17+ mpg range. It will be interesting to run several more tanks and get some highway time on at least one of them to see if this 3640 lb truck will break 18 MPG. In any event I have no complaints with smooth idle and instant starts and great responsiveness.
I checked several plugs again today. Having been thru several tanks of fuel now, checking the plugs from a 30 MPH shut down, I noted the elimination of fuel rich carbon buildup. For todays check I pulled them after idle time...as I noted a distinct reduction in fuelish exhaust stink and a much smoother transition from 0 to high cold idle (1200 rpm) and then down into warm idle (800 rpm) and finally into hot idle (550 rpm) as the primary main continued to be leaned down. I've not made any changes to the primary idle jet yet, which all indications are is a bit small for the engine, however, I suspect that replacement and check is pending in the next tank or two.
Here is the typical condition of the plugs, pulled variously from the ends and center of the engine.
So, for the record, I've ignored all the interweb naysayers, (perhaps they don't try to tune their Weber combinations or understand how to do it correctly) and follow Mr. Langdon's instructions -- Lean the primary main till you have drivability issues then bump up one if the issues are too bad, pick up the difference on the secondary main with larger jets, perhaps as high as a 165 until its too rich at WOT and back down one there. Larger secondary mains will not impact fuel mileage since you're doing most of your driving on the primary barrel.
And in that vein, I installed a 160 secondary main jet this afternoon and will get John Lee out for a nice run on RT 1 tomorrow or Monday since there are some nice hills and its posted 70 MPH here around Sanford and parts North.
I suppose its about time to send a link for this thread to the Prior Owner as they asked for occasional updates on Pap's truck as I prepped it for regular driving after its long sit.
Updating to current carb settings....
Cold Idle: 1200/800 rpm
Hot idle: 550 ish rpm
Primary Idle Jet: #60 (Large body jet)
Secondary Idle Jet: #50 (Small body jet)
Primary Main Jet: #130
Secondary Main Jet: #160
Idle mixture: 2.75 turns out from bottom
Idle speed/butterfly adjustment: 1.5 turns in from first contact with linkage
HEI timed 18 Degrees BTDC (35ish degrees all in w/no vacuum advance hook up at 3000 rpm)
Plugs gapped at a strong 45 thousands - plugs now burning brown