Why are you using such small diameter props? Those are meant for outboard boats and light bow riders. Use a mirage+, a bravo or a rev4 as a baseline.

I'm still wondering the same thing.

I'm still wondering who performed the swap, was the engine complete, any tuning or timing, carb or EFI... Sounds like the first issue is that the motor is acting like a pig.. All the props in the world won't fix a power issue.

Be nice to get some answers to the questions were all asking.

You know if he installed a 502 long block and used all the 454 stuff, then no wonder he can't get over 5000, it's hitting the rev limiter. 502 should be able to make it to 5200

Prop slip has nothing to do with it being a pig, a 330 in a 40' fountain although slow as PHUCK, would still achieve good prop slip numbers if everything else is ok.

Unless you were using small diameter props. Stepping up to an adequate prop reduced his slip but made no change in top end, which was anemic for a 502. There is more going on here than a prop, and focusing on that right now is just plain idiotic.

You experts carry on....

Or maybe the op is just trimmed all the way down.... And he has a 1.65 ratio....

I'm with you on that one!

Here's another thing. Has the boat been weighed recently?