355 cu Carb Choice?
 

Which of the following carbs would you go with?

355 cu
Vortec cast irons
Air Gap
Hyd Roll CC HR XM270
Max RPM 5200


Edelbrock
PERFORMER SERIES CARBURETORS - 600 CFM - ELECTRIC CHOKE, MARINE

Holley

600 CFM Four Barrel Carburetor
Model 4150; Electric Choke; Mechanical Secondary Double Pumper; Universal Performance Marine

Currently running a weber 600 but is around 15 years old and just want to replace.

I know some will think that a 600 is to small but most carb calculators
Think I should run 600 at most??

Thanks

The Edelbrock is basically the same thing you have on there now. I personally would run the Holley (and it would be a 650 cfm). :drink:

fixx
 

i have the same cid,same cam but aluminum heads,,im running a 750 cfm holley and turning the motor to 5800 rpm's..

i have a 350 vortec same intake aluminum exchaust etc, holley 650 dual feed mech secondarys electric choke rpms 5500 had a edlebrock on and trade it for the holley and what a difference

5800 is where your motor runs the fastest ? Or is it because you have a lower pitched prop to have 'rip your face off acceleration.' LOL.

Reason for asking is that this cam (hyd roller XM270HR not the flat tappet XM270H) on a 5.7 with aftermarket heads typically runs strong to 5200 or so rpm.

The flat tappet XM270H has following specs:
Duration at .050 inch Lift 226 int./236 exh.
Advertised Duration at .006 lift 270 int./286 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.480 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.489 in.
Lobe Seperation Angle 112

The Hydraulic Roller XM270HR has the following specs:
Duration at .050 inch Lift 218 int./224 exh.
Advertised Duration at .006 lift 270 int./276 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.495 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.503 in.
Lobe Seperation Angle 112


Sorry for sidetrack, but TexasRPM has been answered on another thread.

fixx
 

that is how the motor is set up,,it likes that rpm and its real snappy through out the rpm range,,im turning a 14x24 labbed ultra prop and can wing the motor to 6200 on a long stretch but try not to..i also have a 14x26 p ultra that i can spin around 5400-5600 rpm..

i like the fear full look i get when i can the throttle and the boat leaves the water when i take off,,kinda looks like this:eek: then im nose down and gone..:drink:

Cam RPM
 

I have to say that my 355 is running a CC XM270 HR and peak HP is right at 5200 RPM. I believe in order to spin up to 5800-6000 a much more radical cam would be needed?

fixx
 

i run roller springs..300 psi on the seat, i also have a lite weight crank and 6'' h-beam rods and srp pistons..i also have a lite boat and i degreed the cam in @ 112 instead of 114 ..i took out the 2* that is machined into the cam..

That's exactly why I posted the two cams and their specs, to see which he has.

The Flat Tappet XM270H will go near 5800rpm.
The hydr roller XM270HR will usually go to near 5200rpm.

Since no answer to which cam he has, I'll assume the XM270H.