Hey I have the same issue I have a 73 biesemeyer 22.6ft cruiser and i know its a heavy b!tch but in the water I can only get the boat up to 3000rpm an running about 40mph with bimini up. Out of the water I can get it way past 3000 the motor is a 455 with about 35 hrs on a rebuild but unsure of the mantaince.  jet is a 12 jc berkley. I have a 8867 1406 weber 4 barrel unsure of the cfm but but I think 650?

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Yes Holley needs at least 6 psi

So I hooked up the tach attachment on the multimeter and when I am at 2900 rpms the tach is off because I am hitting around 4200 rpm.  I installed the new fuel lines so hopefully when I get to the water I can get a few more rpms.  I will also see if I can check my fuel pressure coming out of the pump and see what it is at.  I want 55!!!  I appreciate all the input people.  I am going to double check the output specs of the dizzy and maybe resend the tach back to autometer for a replacement.

Yeah hopefully I get some time tomorrow to check it out.  Does anyone have any suggestions for which timing springs to use in my MSD?  I have the fast ones in now, thinking about going for the middle ones to see if it makes any more difference for cruising speeds.

So I checked today, and I have 6 psi coming out of the pump when I disocnnect the ignition and crank it.  I decided to pull the stone filter off of y carb, and there was little pieces of stuff that almost looked like sand in it, I think it came from corrosion inside my stainless braided line form the pump to the carb.  I hit it all out and ran some carb cleaner and an air hose through the line.  Maybe that was my problem, it wasn't allowing full fuel flow at WOT.  opinions?

Haha i did this last year with my boat! I only hit 3000 with my 460 and could not figure out why!? Its just your tach, its on the wrong setting.. now im at around 4500 r's. Chech the back of your tach (: