My set up is twin 502 cu in gen 6 big blocks crate motors 450 HP at the crank
Impco Exhaust and Exhaust tips.
Basically a stock motor.
I am running a duel feed 850 CFM Holly Carb as recommended by the crate motor spec sheet !
Plugs are a brownish but slightly more blackish color.
Once up on plane it runs really nicely!
My problem is getting up on plain I have a slight bog in both motors, at 1500 to 1600 RPM's , once I am past that slight bog it runs great.
The carb responds to adjustment, it idles nicely does not stall !
Fuel filters are fresh.
I do not know what jets come with the 850 cfm or if I have a jet problem at all ?
Any one have any suggestions on what to try ?
Thank you in advance for the reply !

Try backing the idle mixture screws out a 1/4 turn. Also, make sure the accelerator pumps are giving a good shot of fuel.

If thats the worst of it... i wouldn't mess with it. sounds like it runs pretty good.

have someone watch the tails pipes (if they can),I'm betting its a slight reversion problem.Had it once on my friends boat.could watch the water spray being drawn back up the pipe,same rpms as you.

That's interesting. Good advice for others facing similar problem also.

To OP. I'd put a vacuum gauge on it to optimize air screws and confirm you have correct PV while your at it. Like MT mentioned also but make sure your accelerator pumps are working properly. You may have to go up or down a discharge nozzle size also.

GoPros work pretty well for this as well.

sounds like the accelerator pumps are either adjusted wrong or need different squirters.jmo.

When you ease the rpms down towards idle and move through those rpms does it do it? If not I agree on accelerator pumps, if it does maybe idle circuit to lean or rich?