How do you figure that? My fuel pressure is the same 9 PSI at idle or WOT. A regulator is used to maintain a pressure.

Well, I thought I found it, secondary accelerator pump not fully pressed at wot. Still had a a big squirt left. Adjusted the nut, went back out, same thing, 4000 rpm at 3/4 throttle, no grain at full. Called dui dist. got a guy that knew nothing and had to go ask someone each question. They said " doesn't sound like a dist. problem." Gee, thanks DUI. Next will regap the plugs, although starting to think maybe a carb problem. Holley marine 850 double pumper. Carb worked fine on last engine. Only difference on the carb is I removed the choke.

did you check float levels both front&rear?

Only a suggestion, with boating season almost over... maybe pull engine and run on dyno?

Accelerator pump shot has zero to do with engine hp/performance. All it does is quirt fuel in when the airflow change is faster than the carb;s resultant added fuel flow. This keeps engine from lean pop backfire when accelerating.

You probably fuk'd the accelerator pump spec's. You are supposed to have some arm movement left when at WOT as you don't want to bottom it out. Search net for Holley Accelerator Pump Lever Adjustment so you put it back to stock.

So you changed heads cam compression exhaust and ignition and reused carb. Did you tune the carb to the new motor on a dyno,? Checked afrs? Plug chops at various rpms and loads ? I keyed in when you said the arb worked great on old motor, this motor is a completely different anima

Did you remove the choke blade completely or just disconnect the linkage? They have been known to "fly" closed if the linkage was disconnected and blade still installed.

And if you are going to remove the choke blade you might as well go all the way and mill the choke tower off. Then tune.

yes, checked and set them both

it had a spring at the end of travel, so it doesn't bottom out, but you could be right about I made ot out of spec.