44 idf's on pinto base jetting

2015/09/23 18:49:51

Drewdog

Hello all,
Could anyone give me an idea on the base jetting for 2 44idf carbs on a mild road/ group 1 style pinto? Just need a rough idea to get the car started it will be dyno'ed later....
Cheers Drew...

2015/09/25 12:58:08

war

hi drew,
I went through this last year with new twin idf 44. cant remember the jet sizes, will look on the week end.
I found this info below really helpfull in tuning. (ps it was fun)

It is most important to verify all linkage and levers are installed without binding and the linkage opens to full throttle and is allowed to close to the Idle Speed Screw. This is the number one and two reasons for tuning errors, improper linkage installations and over tightened linkage nut, causing binding in the linkage assembly.
The Individual Runner carbs, IDF, have individual Idle jets and mixture screws for each barrel. They also have an additional air bleed screws and lock nuts. This is not used for idle adjustment or idle quality. The settings for these screws should be closed.

Standard IDF Settings:

Speed screw ¼ to ½ turn in after contact with lever maximum.
Mixture Screw 1 turn out from lightly seated.

“Lean Best Idle” Procedures
After confirming the linkage allows the throttle lever to seat against the Idle Speed Screw. Back off the Idle Speed Screw, then turn the screw in until it contacts the throttle lever and turn it in ½ turn. Turn in the Mixture Screw in until it “LIGHTLY” seats, then back it out 1 full turn. Loosen the 8mm wrench size nuts on the “air bleed” screws, turn in the air screws until it seats then tighten the nut.
a.      Start the engine, it will run slow and like a tractor. As long as it will stay running, the idle speed is not important at this point.
b.      First, turn in the mixture screw until the engine runs worse, then back out the screw ¼ turn at a time. The engine should start to smooth out. Continue to back the screw out ¼ turn at a time until the screw does nothing or runs worse. Then turn it back in to the point where it ran best. You want to tune the engine by sound. Adjust each mixture screw to the best, fastest and smoothest running point. Do this procedure with each mixture screw.
c.      Now you may adjust the Idle Speed Screw. It should be sensitive and only require ¼ turn in or out to achieve the idle speed you like.
d.      These carbs are commonly used in pairs, this makes the synchronization important, be sure to bring the high flowing carb down to the low flow carb. Then bring them both up to “proper” Idle speed. The Idle Speed Screws are not opened more than ½ turn in.
e.      After synchronizing multiple carbs, reconfirm steps b. c. & d.

“Simple Rules for Calibration”

If your mixture screw is out more than one turn like 11/2 turns then your idle jet is too lean, go up one half size on the Idle jet.
If you mixture screw is not out one full turn, something like only 1/2 turn out from seated then your Idle jet is too rich, go down one half size on the idle jet.
This is all based on the important fact that your speed screws are not open more than ½ turn if they are then that is also an indication that you have a lean Idle circuit. You are cheating by opening the throttle plates and exposing additional progression holes in the transition.

2015/09/26 13:21:53

Drewdog

Great, thanks, thats some good info, collecting and printing as much stuff about them as I can, can't find a tuning book like the one for dcoe's of which mine is almost worn out

looking forward to the fun and games...
Thanks again Drew...

2015/09/27 15:58:25

mario

What cam and what size chokes are in carbys. Cheers Mario.

2015/09/29 16:28:37

war

hey drew,
couldnt find where I wrote it down, but found all the other stuff cc of the head the bore etc.
the webers came set up with dual pinto setup in mind from palmside.
I found the ignition timing a challenge.