Thank you so much for the pictures!
Do I need to measure these ports? If so, how?
It's helpful to have a baseline. So the ones can, sure.
Smooth shank of a drill bit is the cheapest way. The real small sizes require a set of microbits which you can get from hobby shops and machine/industrial supplies. Don't sweat that for now. If you have open ended wire feeler gages, you can use them too.
Transition slot is exposed about 2mm on primary side.
That's 0.078" if my conversion is correct. Welcome to the world of mils and thousanths of an inch!
Looking at the photo, it looks to be at least .060"
That opening is feeding fuel at idle. The amount above the throttle is bleeding air into the idle mix.
When the primary throttle blades are closed a little more, the idle won't be so rich. The transition off idle will probably also improve by going richer as you come off idle. That alone may be enough to eliminate the hesitation.
Turn the idle speed screw down and the count the turns open to reveal .020 and .040" of the transition slot. Write those numbers down. That's the typical operating range for a primary transition slot when everything is tuned in. Now you'll know how open they are without taking the carb off.
With the throttle blades further closed, the rpm will drop. Increase the timing advance to bring that up.
If you have no other reference, use the engine size and cam duration at .050 from this chart as guideline.
Distributor starting point for a curve
Secondary is open a little.
OK. If need be, that can be used for some fine tuning. I'd leave it for now. Lets assume the secondary opening is pretty close to what should be and therefore no point in messing with it unless really have to.
All ports appear to be equal sizes on primary and secondary metering blocks
On a 4 corner idle carb they may be similar.
The sizes on the bleeds are 73 and 31
OK. That's fairly typical sizes.
73 represents .073" hole for the primary idle air bleed
31 similarly represents a .031" hole on the primary main air bleed.
If the secondaries are the same, you got it.
The metering blocks have 3 air bleed locations. Unfortunately that's all too common these days and frequently makes inconsistant fuel delivery.
That said, I wouldn't sweat it right now. The bleeds can be removed with an allen key, so that's nice.
It looks like the idle fuel restrictions are located in the high position. Sometimes this causes inconsistant fueling with hot cams. Unfortunately very common on new carbs these days. I wouldn't sweat it right now. But that is the first mod I would make if it was on my bench.
I'd say just try tuning the way it is.
One change at a time.
The change I would make is the primary throttle position and then adjust initial timing.
Make both adjustments with the engine warmed up, distributor vacuum advance disconnected and a golf tee or similar plugging the manifold vacuum.
