Sportfire bow rise / porpoise

[Dr bob]

Hey , has anyone moved the fuel tank on a sportfire I/o to the bow ? I rebuilt my 4.3 and out drive and the boat wants to porpoise at cruise and has a lot of bow rise when loaded down with 4 people. I have plenty of power to get on plane . It just seems heavy in the rear . Are trim tabs the answer? I just don't want to drill holes in the transom. The 4.3 has 9.5 comp stock marine cam with 1.6 roller rockers an Astro cast high rise intake ported heads and a 600 carter carb with thru hull exhaust and runs great .

 

[Skip 7750]

Trim Tabs

Put Bennett or Lenco tabs on it and your problems will be over. There will be zero loss of speed and porpoise and bow rise will be gone. There are no downsides to trim tabs. They work!

 

[Dr bob]

Thanks , I was kinda thinking that I was looking at the Bennett 10x10 but seems a little big for the boat . What size is best ?

 

[Hack]

Just a suggestion: Try putting 100# under the deck up in the bow. And if you can try a 4 or 5 blade prop, which will help with stern lift.

My 219 Persuader (BBC/Bravo), would be a real carnival ride, coming out of the hole and trying to get on plane. I swapped to a Hi-five prop and that tamed it quite a bit, which allowed me to make more effective use of the trim tabs.

 

[Dr bob]

Next time I get it out I was going to through some weight up front and see how it acts . Thanks