"Not really" opens up the possibility to maybe.
I am not talking about whacking the throttle open. I am asking about a gentle tip-in. If the idle speed is high, it can and will mask this.
Here's what I would do;
First, it's important to;
make sure the PCV system is plumbed properly and functioning as designed, that the secondaries are closing tight but not sticking, and IMO, that the Vacuum advance is plumbed to the spark-port.
Secondly;
I would pull the carb off, put the primary throttle on curb-idle and keep it there, then flip it over and check that the T-slot exposure is at least square to a little taller than wide. If it is not, then I would make it so, using the curb-idle screw. After this I would NOT touch that screw again, for a very long time.
Next, I would flip it back right side up, and set the mixture screws to 2.5 turns out, then reinstall it.
From this point on, DO NOT adjust the speed screw. If the idle speed is too fast or too slow, adjust it with timing, to 550/600 in gear, and about 100/150 faster in Neutral.
The engine does not care about timing at idle......... unless it bangs going from P/N to in-gear, then, usually, it has too much.
The first time that timing becomes important, is at stall.
If it has too much, it will detonate.
If it has too little, it will be sluggish.
sluggish is better that detonating.
Both can usually be remedied
Here's my thinking;
When the idle-timing is excessive (and IMO 18* on a "mild" build is), to keep the idle-rpm in check, the tuner has to slow it down by using the speed-screw. This action simultaneously subtracts fuel-delivery from the transfer slots. So then, to make it idle half-decent, the tuner opens up the mixture screws in an effort to supply the missing fuel. So now it idles.
But when you go to drive away, the transfers have almost dried up, so on initial tip-in, the engine goes lean, and she hesitates or bogs, or maybe just sags.... depending on the severity of the mismatch.
At idle, there is an almost infinite number of ratios of transfer slot fuel to mixture screw fuel, that will deliver an acceptable AFR to idle on.
The tip-in sag is the first sign that the transfers are lazy, due to a lack of fuel delivery. Sometimes, the tuner will increase the idle speed with timing, in a feeble attempt to cover the sag, which is the wrong thing to do. It all starts with synchronizing the T-Slots to the mixture screws followed simultaneously with timing.
