replaced carb with new one, 750 holley, now how do i set it up?
it has four corner idle. do i change each screw the same? how can i tell when everything is set right?

first you need to set the float adjustments and youll want to lean your trailer in the position needed to give the boat the same additude as when its floating,make sure your timing is right,and youre plugs are good....then its just a matter of adjusting the air mixture screws in slowly untill the motors starts to slow its idle,and then unscrew them slowly untill its picks back up and then give them an extra quarter turn.....that 750 should come in around 3/4 turns un front and between 1/2 to 3/4 on your rears.....make sure you run an extra filter in front of the carb,those carbs are great till you get one little piece of crap in them and thell start pukin fuel and washing down cylinders....then give it a good run(carefully) pull a couple of plugs to check your jetting......good luck!!!!!!!

What are you putting it on ?

Is it a vacume or mechanical secondary carb?

From there, someone likely has a similar setup and may be able to save you some time.

offshore thanks
Intolerant mechanical a 496ci with procharger stage 2

Intolerant 1... there is no such thing as a performance vacuum secondary 4 corner idle circuit Holley (except the F700 Ford truck Holleys)that I know of, but I may be wrong. And the adjustment given above is correct, but what may help is using a vacuum gage and setting the screws as Offshore Addiction suggests above until you attain the highest vacuum reading and RPM, using all 4. Make sure to do this several times until you are sure you have eliminated the imballance between the 4 corners, and the achieve the highest vacuum reading (thusly the highest idle speed) you can get. After turning them in and dropping RPM, you will be able to tell when you can gain no more rpm or vacuum by turning them out any further, and thats where you want to be. Make sure you heed the advise of Offshore Addiction and do a plug read after making a good run of a mile or more at steady cruise (try not to idle before shutting the motor off) and see a light brown or beige color is on the porcelain. Remember, the older the plug, the longer you need to go before seeing any change in color. If that looks good, go out on another cruise, and after a mile or more do a full throttle bonzai and shut the motor off as cleanly as you can without swamping the boat, and do another read (this will indicate if the secondary jet selection is correct). The faster you can get the motor shut off, the more accurate the readings... just be careful of unintended backwash over the transom. Pure white is too lean, and obviously black is too rich... a nice light brown is optimal for mileage and HP... Good luck!

hey guys,researcherd this before....holley does make a 4 corner adjustment with vacume secondarys,but in the HP series only....and at twice the price people will usually inform you of that...and as find me said also...dont shut it down to fast...youll hydro lock the motor....even with dry pipes....good luck

If I shut down my motor quick it wouldn't crank for about a 1/2 hour, BB chev hit the starter button and raaaaaaa wouldn't make one revolution, never could figure it out, was it hydro locked? If so how do i avoid this? what carb should I run?

apache 22,if your still on plane and shut down,your exhaust turns into two big vacume tubes,but you should notice water in your oil....if your manifolds are bad,then you should still be able to crank right away....(it takes a few minutes for the water to leak into the chambers or which ever cyl with exh valve open)but usually your motor will start running bad due to the cool water reverting in and destroying your exh valves...and you should still notice water in your oil.....sounds like you might just have a starter bendix swelling up when it gets to running temp....when it cools,it cranks......

I missed the 4 corner idle statement when I responded. Sounds like you have the same carb as I do. The vacume gauge is the best setup for adjusting idle as described above and should be done on the water under load. Alot of people including myself have had problems reading plugs with the new fuels. They just dont leave much in the way of color on a plug. Im not sure if this is related to those of us in urban areas that are stuck with "reformulated" fuel or if its the detergents??? When I was dialing mine in, I had AC Delco Rapidfires in it. I bought a set of cheap plugs in the same heat range and used one at a time in the easiest to reach cylinder. The color showed up much better/sooner on the inexpensive plug. I dont know squat about blower motors however. Good luck and dont get too obsesed with it as I did. My wife no longer allows any raising of the engine hatch when she is aboard.

thanks guys again,

will be doing this this weekend. wife will be at the house not at boat!!