Just fired up my 460, basically stock with a cam. I had it running perfectly with an Edelbrock Torquemaster intake, Holley 750 Dbl Pmpr, ProComp ignition (MSD ready to run copy, uses MSD parts) with the lightest springs and most advance (all advance in at low rpm), and bassets. I just added a Weiand Stealth intake and fired it up. Had to bump up idle a hair. I ran it checked for fuel leaks but didn't hook up water yet, so kept running time low. I let it cool for about 30 mins then fired it up again, fires right up and idles great but anytime I rev it, it stumbles. I'm thinking jetting? right now running 72 pri 82 sec and a 6.5 pv. Going to try running water through it and properly warm it up and I will also try and get a vacuum reading tomorrow. Any ideas or am I going in the wrong direction?

carb has been sitting (drained) through the winter. I'll pop the bowls off and take a look. The advance curve was set up by the shop who built the engine. I'm one even size up on primarys and 2 even sizes up on secondaries. Like I said that was when it was jetted for tiny intake ports (they're a little bigger than 302 ports lol). I was thinking I need to go up a hair. I might also need to adjust the mixture screw or change the pump cams. Right now got the stock pump cams. Maybe upsize the squirters? It's been so long since I tuned a holley. Especially 4 corner idle. Can't remember if I adjust primary or secondary mixtures first.

first does it have power valves in the carb? if so throw those in the trash run 82s in the front and 86s in the back you want it to 4 jet sizes bigger with this set up  plus if it back fires through the carb it pop the valves jet boats like alot of fuel also check your fuel pressure it should be around 7psi good luck it looks good

Personally I like the power valves, you can't get any sembalence of mileage if you pull them.

Will it work? Yes. Will it be too rich in the mid range? Yes

Stumbling has NOTHING to do with power valves and very little to do with jetting, it's the acc pump circuit.

I suspect you need to increase the squirter size to one size larger to compensate for increased plenum volume, and possibly change the pump cam if going up two / three sizes doesn't fix it.

I kinda was thinking the same thing with the squirters. I will try that next. Jetting and idle mix seem perfect since any change I made in the mix made it rougher, which also tells me my jetting is close.

very true on the mile per gall but i thought you owned a jet boat so throw that thought out of your head they get crap for mpg the power valve relies on vacuam they do tend to fail and will couse a stumble on hard exceleration thats why u dont  see alot of them in perf applications and you want your jet to run a little rich in the mid anyways becouse thats where it spends all its time while cruising to help keep things
cool  so good luck and hope fully you can get 20 to 30 mpg out of that jet 

Yes, a PV is vaccum controlled - when your engine is under heavy load, you have lower intake manifold vaccum, and the PV uses that to sense when to enrich the main jets by up to 10 jet sizes. Remove it, compensate the main jet size, and run rich on everything but WOT.

Removing the PV is usually done by novices and others that don't truely know what they are doing as a band aid for the real issue. The only time I see a PV fail is during a carb backfire (usually an ignition problem) - with a protector, they don't even fail there most of the time. When they fail, gas leaks directly into the intake plenum, causing a rich condition at lower RPMs (not just at acceleration).

To me, there are two legit reasons for taking the PV out - that is if your carb is too small and you pull more than 3 inches of vaccum at WOT (like the restrictor plate racers) OR you only idle and go WOT like in a drag race only application. Everyone else is wasting fuel in the midrange (while cruising or pulling someone) as you are typically using about 20-35% more fuel in the midrange than you need to be. If you aren't careful that can foul plugs and wash the oil off of the rings causing excessive engine wear.

To each his own though, if that's how you want to tune, go for it. It works for many, and if it makes things easier on you, great, but it isn't right or optimal. I'm anal retentive on my tune, I want as good as mileage as I can cruising around, and brutal performance when I hit it.

Here is one of my engines (528 ci with a large solid roller cam) I get 15 MPG out of if I drive it mellow and it has enough HP to propel me very deep into the 9's without the nitrous (with I'm shooting for 8 flat).

im not disagreeing with you but i found the dont work with my app  also im not new on here like my avatar states i used to be fast ass ford if you look it up and i dont run all those cubic inches in my 18 challenger with set back pump ,droop,diverter and an A impeller all i run is a 429 taken over to a 440 with SCJ fully ported and polished by mendello 14 to 1 comp 740 lift solid roller on a single plane not a tunnel ram with a berry grant 1350 Dominator  the motor dynod at over 845HP at 6500 rpm and also has a nos plate worth another 400 hp  it pulled theses numbers with no PV and continues to run that way and push the challenger to over the triple diget mark at 102 mph and runs on 116 vp and i dont care about mpg couse its a boat that gos to the sand bar and looks for races.But as for it fowling plugs or washing out the cylenders have had no prob with either so any time your around blythe CA and want to see what a no pv untuned boat  that is owned and built by a novice  come by and ill show u what the ass end of it looks like just ask -BadAssFord-Aquaholic they will vouche for me  but good luck with your boat stc315

Thanks for all the help guys, I will stick with the pv though because I have a experience with tuning with them. I do know that when I drop in a supercharged big block that I will have to get blower carbs that do not have pv's. I think part of the problem might also be related to the pv. I need to dig out my vacuum guage and get a good reading. I'm wondering if with the increased plenum volume, I'm getting more vacuum and causing a delay in pv reaction. We'll see. No time to work on it till next weekend though. Then I will check squirters and get vacuum reading and see where I'm at.
Thanks again!

im not disagreeing with you but i found the dont work with my app  also im not new on here like my avatar states i used to be fast ass ford if you look it up and i dont run all those cubic inches in my 18 challenger with set back pump ,droop,diverter and an A impeller all i run is a 429 taken over to a 440 with SCJ fully ported and polished by mendello 14 to 1 comp 740 lift solid roller on a single plane not a tunnel ram with a berry grant 1350 Dominator  the motor dynod at over 845HP at 6500 rpm and also has a nos plate worth another 400 hp  it pulled theses numbers with no PV and continues to run that way and push the challenger to over the triple diget mark at 102 mph and runs on 116 vp and i dont care about mpg couse its a boat that gos to the sand bar and looks for races.But as for it fowling plugs or washing out the cylenders have had no prob with either so any time your around blythe CA and want to see what a no pv untuned boat  that is owned and built by a novice  come by and ill show u what the ass end of it looks like just ask -BadAssFord-Aquaholic they will vouche for me  but good luck with your boat stc315

I feel like you are taking what I said personally like I was either calling you out or insulting you. Re-read it, I wasn't saying or implying anything negative towards you at all, and I never called or implied you were a novice. If you took it that way, I apologize, it wasn't intended. Your discription of your engine and usage puts you solidly into the case I discribed where you only care about idling and racing at WOT (wide open throttle) without concern for midrange, mid rpm cruising (like pulling the kids all day long at 20 MPH). It's that application and usage where you need to worry about plugs fouling and washing the oil off of the rings with the PV removed.  When you are running the engine hard all day long, with the correct jetting, it doesn't matter - PV or no PV. The original poster is talking about basically a stock 460, which I'm sure you can agree, has a different application and usage than what you are discribing for yourself.

The PV on a dominator is usually only 2 or so jet sizes anyway due to the extra mid idle circuit that the std 4150's don't have, it really helps with the fuel curve w/o a PV. On dominators the PV isn't really needed most of the time, the light cruise is on the mid idle circuit not on the mains. 

BTW - I'd love to see your boat. I like anything that is fast and quick. You must have some damn good heads on there to be making that HP on that low of RPM - and that's pretty damn cool.

Well, finally got around to tinkering with it. I upped the squirters (had 25 pri 28 sec) to 35 primary and 37 secondary and it cured the issue. We'll see how it does when I get her wet. But I think it's good to go now.