454 jet boat- power issue

Hello thought you may be able to help me. Just bought 247 Ultra 2000 with 454 jet. lightning headers leaked and changed them too indmars straight. we took the boat out and its running slow and not getting rpm up either.

top 32mph @ 3400 rpm then it seems to loose power the motor was rebuilt before I bought it. 2 of the cylinders are running lower 89/79 compared too the other at 100 to 120. since you have 454 jet on that big boat do you have any knowledge to help get this boat going again? what could it be carb? headers? etc

it almost seems to bog down to 15 mph at times. I had a hawaiian jet with 454 and it ran 50+++ I know there is an issue but what to look at?

any help would be greatly appreciated....

J

 

On a rebuilt 454 compression should exceed 100, really should be around 125, at least what I have seen. If it is a Hipo model it might even hit 140 PSI

 

Check inside the jet drive. Clime under the boat. Look inside the water intake of the jet drive. I had a 6 pack plastic can holder caught inside. Might be somethine in there. If it is a Berkley drive. Pull the top cover. You can see if there is any rope around the shaft of the jet.