air correction & main jet sizing for 69 365GT 2+2

[perry911113]

I'm helping my friend on the west coast who owns my father old 1969 365 GT 2+2. He has an issue with extremely poor gas mileage 6 mpg. The carbs had some modifications to jets by RPM a few years ago.

I need to know standard part applications for the following:
Air correction jets
main jets
emulsion tubes

I believe the carbs are 40DFI-5

Thanks for your help.

[330GT]

Here is a scan of the appropriate information from the FAF Tuning Tips and Techniques book. These parts should be available from Pierce Manifolds (http://www.piercemanifolds.com).

[tinbender]

There were several technical bulletins issued that addressed complaints about excessive fuel consumption. One calls for changing the main jet to 185/100 and the idle jet to 55/100 and the accelerating pump lever pin to position 29-winter instead of position 1- summer. A later one calls for you to disassemble the carb, take away the cap weber drawing no. 61075.003 without damaging it's seat, drilling a 4th acceleration hole of 1.20 mm, increase to 1.40 mm air corrector ducts, fit a new .065mm idling jet,fit a new 1.85mm main jet, adjust throttle tie length with 134mm center distance, put the acceleration pump control lever in the gate no. 2(long) then assemble the carburettors again and make the usual synchronization.
There is a drawing of where to drill the new hole. I tried to attach these bulletins but i don't know how to resize them. I am glad to email someone the documents.

[tyang]

There were several technical bulletins issued that addressed complaints about excessive fuel consumption. One calls for changing the main jet to 185/100 and the idle jet to 55/100 and the accelerating pump lever pin to position 29-winter instead of position 1- summer. A later one calls for you to disassemble the carb, take away the cap weber drawing no. 61075.003 without damaging it's seat, drilling a 4th acceleration hole of 1.20 mm, increase to 1.40 mm air corrector ducts, fit a new .065mm idling jet,fit a new 1.85mm main jet, adjust throttle tie length with 134mm center distance, put the acceleration pump control lever in the gate no. 2(long) then assemble the carburettors again and make the usual synchronization.
There is a drawing of where to drill the new hole. I tried to attach these bulletins but i don't know how to resize them. I am glad to email someone the documents.

Hi Terry,

e-mail me the file, and I can re-size it for you.
tom@tomyang.net

Tom

[tyang]

Here are Terry's tech bulletins:

[srslusso]

Re gas milage I seem to get 11 mpg cruising normally 80 mph, but if I rev her a lot past 5000 on most shifts ( rare)it has dropped as low as 6mpg. 100+ octane fuel every once in a while seems to make her run better also tire pressures in my Pirelli P4000e s of 35 front 38 back. 1968 365 GT 2+2 11727