Ok I will Check the timing, should be 10 dregrees at idle? And I have a few extra props that came with the boat I will look to see what he gave me but if I don't see a 15 or 17 I will let you know, thank you !

Also if I bring it up another thousand how much more speed you think I will get gaining another 1000 rpms? My speedo said 35 I didn't check it with gps yet I will tomorrow

You might get 8-10 mph.. How well does it plain off with the prop that is on it.. ie takes forever or jumps on plane.

Chris

I checked my prop supply and I have a Turning point brand prop that is a 14.25 by 17. It was used 2 times I had it on a bayliner 2452 which is a Massive Heavy Sled. It had a 5.0 220 hp merc and did 38 with that prop but was hard to get on plane. Your boat is lighter and not as wide so it would probably work. I only found one prop that gave good hole shot with that boat and it was a big ear 15 inch prop.

Chris

If it's Mercruiser Thunderbolt IV set the timing to 8 for stock 10 for better and 12 if you know how to identify detonation which you'd then back out of if you hear it. The distributor and controller will add 22 or 24 degrees as you increase engine speed. There are 2 modules. You can look on the edge of the device to see the advance value if you know where to look.
Then important, reset the idle back down to 725 neutral, which will equal 675 in gear. So's you don't ruin the gears as they engage.
You can also do all in timing by setting it with 32 degrees max timing. You do that with a dial light and rev it to the rpm where it stops advancing. Just do it warm and only briefly run the engine to high rpm, Unloaded engines at high rpms aren't so good.
Maybe 34 degrees if you dare or if it has aluminum heads.
I just got a Formula this season too, Thing crushes chop compared to my old boat. Weighs a lot more and feels good out in the broads of Winnipesaukee.
My boat's a little smaller than yours and has a little bit more on the HP, but effectively darn close. It uses a 19 pitch and does OK. I'd suggest a 17 for yours knowing that. You want to get the rpms.

10 is stock not 8. Dont try 12 on a boat..

Chris

Well it says 8 degrees in Manual 9. The big blocks are 10.

Pure conjecture. The problem with your analogy is the big block makes the same or more torque at a lower rpm than the small block. Show me verified data that the 383 would swing a 23" prop in that size boat. I've tried 23" Mirage, Mirage +, labbed and non-labbed in stroker SBC boats in the 21' size range and they would not in anyway shape or form pull 4800 rpm. I love SBC, but they won't swing that size prop on that boat unless you dropped the gearing or it had a blower.

There's no replacement for displacement. But I'm doing a stroker at some point too. Unless I can talk my brother into selling me his 454 that he's hoarding.

NHGuy my boats on winnipesaukee too! I have it parked at my parents place right in the channel if you're heading into paugus bay from weirs last condos on the left after Naswa. Maybe you could swing by and help me time it lol jk but I'm having more issues now anywhere from 3/4 - WOT it will sputter and fall on its face like its being fuel starved, runs good at 3000 and under but anything over that it will sputter.. If I throttle down and run at 3000 it will be ok but if I throttle up it'll sputter again.. If I go back to idle for a bit and come off plane it'll run at WOT for about 10 seconds then die out again. I changed all the plugs wires cap rotor fuel water separator and the fuel filter in the carb.. They didn't look to bad. I just ordered a fuel pump so that's my next guess lol one thing I didn't try was taking the gas cap off to make sure it's not a clogged vent.. Any suggestions???

curious as to what you came up with for a prop size and pitch. assuming you go the thing to rpm more than 3000