Carb and manifold upgrade?

[Svshaw82]

Hey guys, my boat has a GM 4.3l V6, with the cast iron intake and rochester 2 barrel carb. I was thinking about upgrading to a edlebrock manifold with a 4 barrel carb. Anyone done this before? Could I possibly see any gains? Or would it be a waste of money?

 

[Bondo]

Ayuh,.... Yer lookin' at 'bout a 20 hp increase,... alittle bit of bottom end, 'n a pretty good kick in the top end range,....

 

[Svshaw82]

So you think it's a good upgrade to do? Is my GM 4.3l any different from a non marine engine? Can I just buy normal Edlebrock stuff?

 

[jimmbo]

No, the carb has to be Marine Certified. A 4.3 spinning 5000 rpm with a Volumetric Efficiency of 80% is going to use 306 CFM of air. You are not going to see much gain unless the OEM 2bbl is significantly under that flow rating. Most 4bbls are way too big. Holley makes a Marine 390 CFM 4bbl that would still be more than enough. The Holley 350 marine 2bbl would also be ok, still a bit too big.

 

[Bondo]

So you think it's a good upgrade to do? Is my GM 4.3l any different from a non marine engine? Can I just buy normal Edlebrock stuff?

Ayuh,.... My 4.3l has a 4bbl carb, 'n I'd have it no other way,....

The 1409 is Edlebrock's marine rated carb for yer motor,....

Their aluminum manifold is alright in freshwater, in the brine, find a cast iron manifold,....