I finaly got my boat back from tyler crockit 509 with 420 B&M charger twin 750 carbs 750 hp and max rpm should be at 5300 5400 what prop would be best on my boat 25 outlaw 1999 no shorty or ext box. also engine at low rpm runs like crap rpms go from 1200 to 750 up and down and then it stalls some times some advice please thanks

26p-28p 4 blade to start.

You're dealing with a healthy cam and blower surge. You've got some tuning to do, but her docking manners are never going to be nice.

750 hp i would go more towards 28-30 4 blade or more 425 hp runs 23-24 p

Best advise is to find someone in your area that is good at setting the low speed air screws on your carb. If you attempt this yourself and are a novice I would suggest using the vacuum gauge method, old schoolers can do it by ear. Also re-check the timing. I think blower surge is the coolest thing in the world, if someone knows a way to make my efi units do it let me know

24p 4 blade was stock on your boat with 425hp. I think you will end up in the 30p range

I agree...somewhere in the 28P to 30P...I'm running a 28P with 650HP

I'd start at 28p stock prop.

I would ask the builder about the stalling problems, it will get worse once you put more prop on. Sounds like it needs some adjustment on the carb or timing. If nothing else I would contact Nickerson I'm sure he would be able to tune the carbs.

I have a buddy with a 509 and a whipple on his 25 outlaw that is dynoed at 720 hp and he runs a 28p bravo 1

Stalling at idle seems to be a very common trait with this engine builder. I thought it was just with our engine's ECM, but now hearing about it with a carb engine makes me wonder if he cut class when the lecture talked about engine idling.