Wellcraft cruiser wont plane out 454 Alpha 1 2nd Gen

[Kingfresh]

I recently bought a 26ft Wellcraft 260 aftcabin it originally had a 350 in but had cracked from not being winterized so i dropped a 454 in it and attach a 2nd generation alpha. i figured a 19 pitch prop would be good but, it wouldn't plane out so i went back to the 15 and it wouldn't plane out either even with the trim tabs all the way down. any suggestions?

 

[flipbro]

Not A prop issue! Sounds like a hull or tired or out of tune engine issue

 

[steelespike]

I have to agree If it won't plane with a 15" either the hull has a problem or the motor.
Don't assume because its a new install that everything is right.Check the timing is set right and advancing as it should.
Be sure it's running on all cylinders.Throttle opening all the way.
Do a compression test,note the condition of each plug.
Has the hull been rebuilt?Need to be rebuilt?Perhaps some water is trapped somewhere?

 

[doyall]

Don't know that I can help you with the planing issue but isn't that a bit much boat and engine for an Alpha outdrive? Is it a marine spec engine or an automotive spec engine? Is the gear ratio of the Alpha correct for the application?

 

[Chris1956]

Gee, That big block should plane that boat. The Alpha is a bit marginal, but was used for that application. I would baby it a bit. Make sure not all the weight is in the stern, or she could drag too much.

 

[jestor68]

I recently bought a 26ft Wellcraft 260 aftcabin it originally had a 350 in but had cracked from not being winterized so i dropped a 454 in it and attach a 2nd generation alpha. i figured a 19 pitch prop would be good but, it wouldn't plane out so i went back to the 15 and it wouldn't plane out either even with the trim tabs all the way down. any suggestions?

What kind of "454" did you drop in? Is it a new motor, a reman, a used motor, or something from a salvage yard?

It appears your boat's dry weight is about 7000 lbs, which is not too much for a big block to push to around 40 mph using a 17-19 pitch prop.

I'd say that your "454" isn't performing up to specs if it can't turn a 15 pitch prop up to recommended rpm.