My new ride is really runing rich at idle, so I pull the carb its square bore holley, mechanical secondaries with 4 corner idle. The primary transfer slots were uncovered alot and the idle adjustment screws were each out 2-1/2 turns. My question is regarding the secondary transfer slots. I read here on a previous post that you should back the screw adjustment off and tighten it until it just touches the linkage and go anothe 1/2 turn and that should set the secondary thottle blades. On my throttle plate this does not uncover the rear slots at all and requires anothe 1/2 turn or so to give about .020. Are the rear slots suppose to show from the bottom the same as the primary .020 to .040 ".

Thanks Rich

I think you were reading about a vacuum sec carb... Set both pri and sec throttle blades so from the bottom the transfer slot is showing as a square. then start about 1 maybe 1 1/2 turns on each idle mixture screw. At the same time adjust both accl pumps so they have .015" clearance at wot. With the carb off the car, dry adjust the floats by taking the bowls off and turning them upside and adjusting so the float is centered in the bowl. You may need new gaskets for this...

Anyway once set bolt back on and fire up the engine and don't worry if it idles until the temp is up. Then if it won't idle go 1/8 or 1/4 turn on each throttle screw without worrying what the rpm is you just want it to not stall at this point. The key here is is knowing where you are at so write down each adjustment and make the same adjustment to each throttle screw or each idle mixture screw.

So let's say you reached a spot where it isn't stalling. Now you can adjust the 4 idle mixture screws. If you have a vacuum gage you want to make the most vacuum, if not you want to find the highest idle. You have to do this 1 screw at a time but remember in the end you want each screw the same... Start with a primary and and turn it in slowly until you notice the vacuum drop or the idle go down. Count the 1/8 or 1/4 turns you make now open it up until the vacuum picks up or the idle comes up. Now do the other primary the same way and go on to do the secondary mixture screws. When all 4 are done you may not have all of them the same. This is why you need to write down where you started and where each ended up. Go ahead and set your idle to the desired rpm with the throttle screws keeping them both the same. back off or increase 1/8 turn on one then the other. When you have the idle you want shut off and check each mixture screw by counting turns until it seats lightly.

Say you check each and find this:

1 turn
7/8 turn
1 1/8 turn
1 turn

find the middle ground and set all 4 the same. I'd set them all to 1 turn and fire it back up.... From here if you need to adjust anything (idle or mixture) make the same 1/16th turn on each in which ever direction. I feel it really is key to keep the 4 mixture screws the same and the 2 idle screws the same.

Please keep in mind a 4 corner idle carb is bound to be a touch rich at idle a lot of guys have them and close the secondary mixture screws and the throttle blades because of this and defeat the reason for the 4 corner idle... they should have bought something that idles just on the primarys...

Thanks Dennis- appreciate the info.

Rich