Dump that vacuum secondary carb and put an 750 mechanical secondary carb on it.You will see better fuel economy and better performance with your jet

what impeller?

48.7 MPH

my guess is 50-55 mph. my buddy has a 21.5 foot daycruiser with a panther and BBC and does an honest 45mph. if he can get that tugboat up to that speed you can fo sho hit 50-55....    

tahiti with a panther you dont have much going for you...might be faster in reverse 

Yep. My guess is a solid 53.4

53.4....That's pretty bold. I was going to go with closer to 50.2 to maybe 51.1, but to go all the way up to 53.4, too rich for my blood...


The Panther powered boat we had had a 360 cubic inch AMC in it, balls out with no beer or ice in the styrofoam cooler and all the anchors and skis and crap on the shore, at 4900 RPM we got her to a screamin' 44 MPH on a Stalker II radar gun....

Sounded killer though.

GT

Now if were talking eBay or craigslist talk its got to atleast do a hundred 

my 21ft had a 454 with demon 800dp carb. i could run just at 50 mph wide open. the panther pump is a great pump. you just need to make sure the clearances are good. once your pump is dialed in they last forever. I had tom at jet boat performance go thru mine and when i got it back it was a whole new boat. i did not pick up much speed but i was turning 1000 less rpm to get there. and that saved my motor.