This is a piggy back off my other post about mechanical 6 pack wide band readings. I'm trying to lean the cruise from off idle to about 3k so took all three carbs off and found the IFR to be .031 on all three with the idle discharge holes a lot larger on the center carb, center carb is the only one with idle screws. Anyway put .009 wire in all 6 IFR's and it was way to lean, like 19ish a/f ratio at idle drive, could not get it to idle. So took the wire out of the center and it was better idling in drive still lean 17ish but would idle ok. Took it for a drive in the subdivision and at 1,500 rpm cruise it is at 16.3 still to lean, with no mods before it was at 12.3.
My question is can I have one IFR with no wire and keep the wire in the other IFR's per outside carb? Like RF and LR on the duel plane intake? or dare I go with some .005 wire in all 4? I know this winter I'll have to drill and use set screws in it to make any change permanent.

Thread them. The link shows what is needed. Must use a bottoming tap. If you are comfortable drilling/tapping small holes see if a local machinist can help. Last resort I can do it. I also have the set screws needed.

http://racingfuelsystems.myfunforum.org/viewtopic.php?f=25&t=18

I wouldn't stagger them like that.

How about this; since you are going to drill and tap them for screw-in bleeds anyway, why not drill the IFRs a bit bigger (say .001" or .002") and use the same wires? Or wire down your IABs. Either way should fatten up your idle a bit. And will give you a chance to see how it acts with each combo and if it likes one better than another. And I would concentrate on the center carb unless the outboard's idle circuits are way screwed up.

And have you checked your slot feed? By 1,500 your throttle plate position should be pulling on the slot a good bit.

Don't get too hung up on idle A/F ratio. Just give it what it likes whether that is in the 13s or the 14s. Get the mix screws in the 1 to 1 1/2 range with a solid idle and call it good. Then go to the slot for off idle and the air bleeds and emulsion holes for main circuit actuation timing.

On a side note, my old outboard carbs had idle mixture screws that were plugged over with lead. Any chance yours do too?

Good points, I just pulled the .009 wire out and decided not to try anything smaller in it. When I pulled the outer carbs I noticed the throttle blades were not exposing any slot so I set them for .020 and will not touch them. This is a old direct connection mechanical setup so no adjustment on the outer carbs just the small idle feed below the throttle blades and what I presume is a transfer slot. The center has no wire in it and the idle feed below the throttle plates are much bigger. I'm going to play with the timing and idle screws and see what happens, maybe now that the outer carbs are "cracked" open a bit it will lean it out some.
I do have a mill and precision lathe at work so drilling the blocks and set screws should be easy

What equipment are you using for measuring AFR?

Thanks, Mark

I find with 6-32 x 1/8 set screws you can run the tap in 4 to 4.5 turns and have the set screws thread in enough, without having the threads go thru to the idle well which you don't want.

Innovate MTX-L