carb/jetting ? on 454mag
 

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.

Re: carb/jetting ? on 454mag
 

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.

Re: carb/jetting ? on 454mag
 

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

Re: carb/jetting ? on 454mag
 

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.

Re: carb/jetting ? on 454mag
 

................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

Re: carb/jetting ? on 454mag
 

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.

Re: carb/jetting ? on 454mag
 

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 :evilb: BEFORE HE SHUT IT DOWN. SCARY RIDE :drink:

Re: carb/jetting ? on 454mag
 

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!

Re: carb/jetting ? on 454mag
 

An MSD won't help a thing power wise.