Carter 750 rebuild questions

Putting in a kit in a competition 750 and have a few qualestions

First. How do I ensure the mixture circuit is clean ?
I've removed the screws and cleaned that passage out but how to I ensure the passage supplying fuel to the screw is clear ? I can't seem to find the supply

Second - I assume these are stepped needles? I've seen diagrams but never seen one in person ( see pic )

Lastly the passenger side primary jet was in the hole but not screwed in. Looks like it vibrated loose. looking at the jets the primary are .098 and the secondary are .096.
To my simple brain this seems backwards. Since one loosened up I'm thinking someone went through the carb once before - could they be backwards ?

The carb sat for several years with fuel in it. Many passages were plugged. When it would idle I could put my hand over the top of the carb and the engine would clear up and idle better. I checked for vac leaks and found none. After looking the he carb it was clear there was a lot of passages hindering fuel flow.

there have been issues with that carb but I have one that I am going to rebuild/use. I bought it for $25 way back (on here) so it might be one of the problem ones but I knew that going in. If you have a bucket of soup I would soak it in that & several times go in there & swish it around then let it set some more, then rinse it with solvent & blast out the passages with brake kleen then shop air. I'm sure it is the std 2 step rods (cruise/power). that's all I can add for you.

Larger jets in the front. The metering rod takes up part of the jets area. Look at an Edelbrock manual for instructions. Except for the inlet check valve (looks like a jet with a check ball in it) used for the accelerator pump they are very similar.
Doug

I use pipe cleaners for fuel passages. the edelbrock 1467 accelerator pump (tan colored) is the best; blues aren't as good. as said; larger jets in the primarys.

I've had pretty good luck soaking them in carb/parts cleaner using an ultrasonic parts cleaner. I found a good used one through craigslist and use the heck out of it for neglected carb cleaning: everything from cars to motorcycle and small engine carbs.

Then spray all the passages with aerosol carb cleaner. I'll sometimes carefully use a welding tip cleaner to run through suspect passages. I know that's not recommended. The pipe cleaner approach mentioned is a safer one.

Ditto on the previously mentioned accelerator pump plunger.

Generally I've been able to get them running ok again. I've never cared for the step up rod design, but it's sure used in a lot of different carburetors.

That said, I did have one of that style that never would cooperate no matter what I tried. That one went down the road at a swap meet, with a tag saying it had been gone through but would not run right. Guy took it for $25 and was happy to get it. He said he could fix it.

Being simple minded I've always preferred the Holley jet number scheme for tuning. The combination of jet, step up rod and springs always drove me crazy.

i'm thinking that with the blue accelerator pump and .098" primary jets that the carb is a 625 not a 750.

Guess I shoulda ran the numbers. You're correct. 625.

Sounds like someone was in there already.