79formula

actually I am not trimming at all. If I bring the drive out the boat porpoises bad. I just leave it tucked in. The bow lifts too much on its own. Needs tab down and drive in to keep it smooth. My compression is 9.75. I mirrored this build except i have an air gap intake and my cam has 3 degrees less exhaust and thiers made 412hp at 5600. Granted they had headers. http://www.chevyhiperformance.com/te...cam_355_build/

GPM

Any chance the hull has a weak spot and it's flexing

79formula

I dont think so, the transom and motor mounts are all new. The floor is rock solid. There is no stress cracks. My skeg was crooked and rough from where a chunk was missing and I half ass patched it. I fixed it and smoothed it all out with a belt sander so it should give the prop some cleaner water. Would a messed up skeg cause my issues? I will test it out tomorrow.

GPM

With the drive tucked in the motor is trying to bury the bow in the water, but you're running bow high. I could be wrong, I would check the hull for soft spots from the motor forward. Have someone video a fly by so you can see what it looks like from the side. I doubt the skeg would have anything to do with it.

79formula

just for kicks, I put a straight edge on the keel. The cavitation plate is 1/4 inch below the bottom of the boat. Maybe I need to set the angle of the boat a bit more nose down with the tabs so when I trim to neutral instead of down the bow will not rise more. I know I have tons of bow lift.

downforce137

iTrader: (1)

putting the nose down will not help increase the speed. you need to get the boat up and out of water. trim it up and put the tabs up.

sprink58

This is a long shot but something might be hydrodynamically screwed up with the lower unit on the Alpha. Do you have access to another drive that you could pull the lower unit off of and try it? One other thing to consider would be to switch the drive to an Alpha Gen II. My brother did it on his F3 with good results using an old style Transom Assembly. He did a bit of grinding and shift cable modification but it worked well for him.

Another idea would be to move the tabs inboard towards the keel. This will for sure give you the ability to find the sweet spot angle without over trimming the drive.

79formula

Maybe I should try putting the tabs all the way up, and putting a little trim in it to keep the bow up. If I pull the tabs up and leave the drive tucked in the boat jumps up and down. As i am running currently though i am getting the spray to come out about 1-2 ft from the back. The spray is coming out behind the rear bench, I have a full sunpad.

79formula

Feels like i need to try one of those stern lifting props.

GPM

A cleaver style would give you stern lift.