Does my tuning with new A/F look correct?

[my5thmopar]

I have my Innovate MTX-L installed and now I’m playing. I don’t have any drive-ability issues, I’m just trying to get the carb properly tuned. The plugs are a little rich and sometimes slight black smoke at WOT. Here is what we are working on. 72 Dart 318, .030 over stock flat tops, Comp XE256 has intake duration of 256 and.447 lift. Timing set at 18 initial and welded slots gets it to 34 when all in. Performer 2176 intake and Eddy 1406.

I called Eddy and the first words out of his mouth…that carb is too big for a 318, and you can’t tune with an A/F meter, they are for fuel injection not carbs. Also, says I need the silver spring. What!!! That will go richer as the rods go up quicker when vacuum drops…Not sure he knew what he was talking about I think I’m done with them and will ask FABO.

I’ve been running 7 on the calibration chart. Today I’m at 12 on the 1406. Primary .095, rods 75x47 with orange step-up. Eddy says carb is too big that’s why I won’t get the A/F down. The secondary pretty lean at .086 but, no smoke at WOT now.

When I tune the idle to max vacuum, the A/f is 12.3 to 12.5.

I get 13.6 to 14.2 when cruising at about 60-70 on flat ground.

I get a slight lean to 15-15.5 on the meter when I hit a hill, from cruising but, disappears quickly. I don’t have any hesitation and from what I read this isn’t anything to worry about.

At WOT I get a momentary drop to 10-11 but goes right back to 12.5.

Do I need to be concerned with any of the readings here? According to Eddy, There isn’t anywhere else to go but to a smaller carb. What say you, carb gurus?

 

[Woods74]

Looks good, remember, it's not fuel injection. As long as you don't lean out and start driveability issues your good. It's gonna wander around.

 

[TrailBeast]

Shoot, you are describing my 318 fuel system and mixtures almost to a T.
Even down to the .095 jets.
1406's are not too big for a 318.

The momentary rich on acceleration is the carb pump dumping a shot, and mid 13's to low 14's is just about perfect IMO.
Any leaner and you get more engine heat and a tendency to feel a little weak under a heavy load.
Sounds like your right in there to me.
Also I found that trying to tune leaner than you already are at idle tends to cause
missing on warm start ups.

 

[my5thmopar]

It seems the 12.3-12.5 seems a little rich at idle but, I don't see getting it down without purposely turning the mixture screws in. Maybe go to 11 on the chart with the .092 primary jet and 71x47 rods. I'll also check the float height while I'm in there. Any thoughts?

 

[Woods74]

Richen your idle to suit max vacuum, and best idle quality. Not placate to a readout. With my mild 225 duration cam 12:1 is buttery smooth. 14:1 sounds like a rumpity drag strip hero. When you stomp on it the total a/f number including enrichment/WOT should be between 12.5 and 13.5. Whatever pulls the strongest, 12.8 is common.

 

[Aaron65]

Don't touch it. You're fine. The only thing you may want to do is use a pink step up spring, which may help your momentary leanness when you press the pedal down for hills. It won't richen the mixture, it'll just richen the mixture sooner as vacuum drops.

 

[ir3333]

you are set up fine.WOT should be a bit rich 12 - 12.5 and you could clean the idle up a bit.
but looks pretty good.

 

[Aaron65]

It's kind of funny how different engines are...the 1406 on my Ford 289 runs .098 jets and 71x47 rods to end up in the exact place you are. It, however, may actually be too big for a 289.

 

[TrailBeast]

Richen your idle to suit max vacuum, and best idle quality. Not placate to a readout. With my mild 225 duration cam 12:1 is buttery smooth. 14:1 sounds like a rumpity drag strip hero. When you stomp on it the total a/f number including enrichment/WOT should be between 12.5 and 13.5. Whatever pulls the strongest, 12.8 is common.

That was my point exactly.
Mine does the same thing if I get leaner than about 12.5 at idle.
Sounds like it has a small lumpy cam (which is actually just a lean miss) until it gets good and warm.

 

[Inertia]

It, however, may actually be too big for a 289.

Nope,, it's perfect for a 289..

cheers