trimman

i have a fresh rebuilt 454 mag w/ 30 hours, engine builder used decent parts for reliabilty and performance , scat crank, which was polished and balanced, manley valves,speedpro pistons, comp cam,part #11-236-4-, went with revoltion exhaust, motor is in a 25' sunsation, as of now am running my stock quadrajet, engine builder says it can handle a 750-800cfm carb, usable rpm rang is 1600-5600rpm , question is what carb to go with and can i get the carb set up already w/. the proper jetting give or take a size shipped to me. Boat currently runs 73 mph spins a 23 labbed mirage at 5150 rpms. Any suggestions would be appreciated.

1BIGJIM

I am currently using the same cam in a 496 had it in the 454 before stroking it. I had the Edlebrock 750. It was OK. I changed to the Sea Demon 750 Double Pumper and it works great. I jetted up because of the more cubic inches.
A 750 will work fine, the Q-jet will work fine and is a good carb also.
Is that 73 GPS?? Without doing the math that seems alfull fast for that setup.

BY U BOY

I AGREE I HAVE A 21 SCARAB WITH A A MILD 450HP 454 AND I AM ONLY SEEING 65 GPS. TRYING TO GET TO 70

Whiteknuckle

trimman,
The q-jet will do a nice job on that engine. Chances are it is a 750 CFM Q-jet. You only need to richen up the secondary throttle rods. You can buy a complete set of rods from Edelbrock. Dennis Moore's Big Block Chevy Marine book also has a list of the Q-jet rods. They are so easy to change you can do it in the boat with the engine running.
73 MPH at 5150 with a 23 inch prop, is a little on the optimistic side. Speedo or tach may be off.

minxguy

................454 Mag MPI with EMI headers, 72 on the GPS with me at 165 lbs, neighbor 265 lbs and an indicated 1/2 tank of fuel in 2 foot chop. Donzi 22C Ken

SB

Some boat set-up problems or engine is not making that power by design or by tune.

BTW: many of the Sunsations fly with comparable power to other boats. They are lightweight, narrow, and decent bottom, and etc, etc adds up quickly.

BY U BOY

I DON'T THINK I HAVE AN EFFICENT HULL AS THE 22C. THE SCARAB IS A LITTLE HEAVIER AND WIDER BUT I WILL STILL DUMP MONEY INTO IT.
I HAVE BUDDY RUNNING A 22C 496 WHIPPLE CHARGED WE SAW 90 BEFORE HE SHUT IT DOWN. SCARY RIDE

trimman

Thanks guys , my mechanic said boats running fine , theres room for a little improvement,but leave it alone. i'm running stock merc ignition system thought about adding msd, don't know if that would make a difference, but i was trying to squeeze another mile per hour or 2. before the engine went i was running 69 gps w/ a stock 454 mag ,stock exhaust i think my tach is off , my boats only has a 7' beam and my prop has been tweaked by DAH in wisc. . A buddy used to have the same boat as i do same motor set up only w/ whipple w/. a chiller on , boat did 87 , it acclerated like a top fuel dragster, that was a wild ride!

Griff

An MSD won't help a thing power wise.