I bought a Pro Systems 950 last year because I thought it would be set up better than a stock Holley HP, wrong. I have a 524ci BBC running somewhere near 700HP in a Velocity 280 which weighs about 4200 lbs with a 1.5 gear ratio in my Bravo 1. I'm getting a stumble when trying to get on plane, after that it seems pretty good. My plugs look white after running 60 miles at 4500 so I know it's lean. I jetted up 2 sizes and hope to check it next weekend. The boat is in the middle of nowhere so I'm trying to be prepared for anything. I'd like to know what size accelerator pumps most of you are using? The carb came with 30cc on both ends. It may just require drilling the squirters to the next size but If I don't have enough fuel drilling the squirters will make it worse. My vacuum at 600rpm in gear is 2.5" so I dropped to the lowest power valves I could. The idle is real smooth so I must be ok there. The accelerator pump cam is the one for the most volume so I have that covered. FWIW my initial timing is 24 degrees with a 10 degree advance all in at 3200.

turn in your idle mixture screws..i usually set them between 1/2 to 3/4 turn,also make sure your accelator has a full throw to it,,if you had to screw in the 3/8 nut and bolt that will make it stumble,i like using the orange cam,this one seems to work the best for me.as for the squirters buy a few sets instead of drilling them.

You need a 50cc acc pump.

Todays fuels burn so clean, that pretty much all plugs will stay white on the porcelain. You need to look at the base circle of the plugs to judge the rich/lean condition.

X2, pat really does a great job with every carb of his I've used before. If you're rolling in to get on plain, you almost don't even need an accelerator pump. Check float level, could be uncovering the jets as the acc pump shot drains the bowl and the bow comes up

I set the idle with a vacuum gauge and by smell, I know it sounds weird but I've been working on engines for over 40 years and I can smell when it's burning right. The idle is perfect, doesn't stumble when going in and out of gear. I keep a close eye on the fuel levels and they are right where Pat said they should be. I used a light and 10x magnify-er to check the plugs. The insulator is white all the way down and the heat signature on the arm is 1/4 of the way up so I bought plugs one step hotter. I should have been more explicit, If I stand on it it off of idle it dies before the nose even has a chance to rise, I have to feather it to get on plan. Once the rpm's start to build I can jump on it without a problem. I think I actually have the orange cam, I'll check it later. I have Lightning headers and to put an O2 sensor in is a bunch of work and my collector isn't long enough for proper sensor placement and keeping the sensor dry. I'm going to run some tests on the accelerator pump to see if the squirters allow the accelerator pumps to evacuate immediately or if they provide a restriction. All recommendations and thoughts welcome.

i would note cam position and get a couple squirters, try way large squirter to se if she'll get on plane, then work down. maybe slosh tubes on back jets.

I finally got a chance to look at the carb and I have the Pink cam which according to a holley book I have, puts out the most volume. I have 35 squirters and I will bump those to 40. Once I get everything back together I will fill the carb with fuel and test the accelerator pump output and timing. I did notice the cam adjustments needed tweaking hope that helps. I thought about slosh tubes, that may be my next investment. Hope to get some seat time next weekend.

Well should be easier to aid in this since you are very familiar with everything involved. I've had to go as high as 40 with acc pump nozzles, and a black cam. 50cc pump in the rear