helping on a 1986 Sea Ray Pachanga 22' said to have 383 sb. Runs great at idle 650rpm no black smoke or smell of running fat. At 1700rpm and still no black smoke and not rich at this point. Now at 2000rpm or so secondaries open and loads up,black smoke and then dies.The carb is a Holly 4160 marine #'s on horn are sae - j1223 9015-1 1429. the carb has been cleaned and new power valve.. Today pulled carb apart to look at jet's and they are marked 76... My first thought is that the motor is not a 383 and the carb is way to big .. with out disassembling the motor and checking the bore and stroke I can not verify it is a 383 or just a 350sbc. any ideas??? should I go to smaller jets ?? like 70's or change out the carb to a 600cfm.
Thanks

750 CFM MARINE CARBURETOR
Electric Choke Vacuum Secondaries
PART# 0-9015-1

Totally fine for 383's .

When you say 'dies', do you mean it stops running ? and you have to restart ? or the power dies off.

Jet size in a carb means almost nothing when it comes to flowing fuel through a carb. Sounds like you have a bad coil.

A 4160 does not have secondary jets. It uses a metering plate to control flow.
The problem arises as the secondaries open, so changing the primary jets will do little to fix the problem.

I would double check the float level setting first with the boat in the water. Does the boat sky the bow as the secondaries kick in??? If so it could be flooding the fuel bowls.
The next option is to try swapping the springs in the vacuum secondary to control the opening of the secondaries.

Your float levels. As you pick up some rpm, it will raise your pressure. Also make sure the choke is zip tied open to rule out it wanting to close. Not sure of your wiring but it's possible your loosing 12 volts to choke? Can't remember if u said it was manual or electric but.....

BlackBaja has a good point also. Would be a nice quick fix, That can be easily overlooked by many.. If you can throw another carb on even if u have to borrow one so u can rule it out regardless. Same thing with coil.

at that rpm your off the idle circuitry so another thing that popped to mind is it's possible one of your jets backed out and is laying in the bottoms of your bowl. Just throwing it out there but hey... U never know.

As a note on a pet peeve: I can't tell you how many electric chokes I see hooked up to the + terminal on the coil. This drives me nuts.

Here's his carb:
750 CFM MARINE CARBURETOR
Electric Choke Vacuum Secondaries
PART# 0-9015-1

like baja said,check the coil,i can,t tell you how many times i have seen people blame the carb for the problem when in fact it was an ignition problem.does the boat still have the 30 year old coil on it?

coils are cheap enough to rule that out,,plus make sure the purple wire to it is in great condition,,replace if necessary.

Maybe a blown power valve in the carberator. Just a thought

I was going to mention thje power valve...also, if that carb has been modified with a weaker secondary diaphragm spring the secondaries will open too soon creating the condition you describe. I think the original spring in those carbs is a black one...if that carb was on a big block and swapped over it may have a weaker spring to allow the secondaries to open too fast for your engine.

Good luck.