Carburetor replacement

[SeaSkwurrel]

I have an 81 Seaswirl Lancer-OMC stern drive with a 350 Chevy. I need to replace the carb-currently a 2bbl Rochester 2GC. Would it be better to go to a 4bbl? What CFM should I get?

 

[Ralph 123]

Re: Carburetor replacement

A 4bbl Eddlebrock marine or a Holly marine can be had brand new for $400 - $500. I run the Eddlebrocks on my 350s and am very happy with them. <br /><br />a 350 needs a carburetor that will flow 506 cfm @ 5000 rpm. No matter how large a carburetor is installed the 350 will only draw in 506 cfm @ 5000 rpm since each cylinder holds 43.75 cubic inches of air. Due to efficiency considerations, that brings you up to a 625 CFM * taken from Moore, "Small Block Chevy Marine Performance" <br /><br />If you get that book you'll see all the carb and intake options.

 

[The Marine Doctor]

Re: Carburetor replacement

You would be much happier with the 4 barrel carb rather than the 2.<br /><br />TMD

 

[RomanRegal]

Re: Carburetor replacement

Raplh,<br />I also asked about carb replacement some time ago. I am ging to replace my Rochester 4bbl quad with an edlebrock, using the adopter to make it work. Question. Is the edlebrock marine carb 625 or 600 cfm. The ones that I have seen all seem to to rated at 600cfm.<br />Thanks Roman

 

[Northern Eclipse]

Re: Carburetor replacement

Ralph and Roman are right on the Mark the 350 works really well with a 600 to 650 cfm Carb but it best when mated with a Duel Plane spread bore intake manifold, with that combo the motor will make good low rpm torque and still have good midrange punch with stock cam and ignition, which is what is mostly required from a marine motor, even if you just go with stock cast iron intake and quadtrajet carb, you'll be grinning Just like the Doctor says "you'll be happy with a 4".

 

[flashback]

Re: Carburetor replacement

I have an Edelbrock on my 350 21' Chris scorpion and it has worked flawlessly for the last 2 seasons......no leaks, like i have heard the holly's are prone to do......I think mine is 625cfm not really sure but it's enough to get me goin about 50mph if i want... but you can kiss a 50 dollar bill good by in a hurry..............

 

[Ralph 123]

Re: Carburetor replacement

Roman,<br /><br />95% sure they are 625 cfm. I'll check tomorrow and if I'm wrong I'll repost. You can also check their website and look up the marine performance series.<br /><br />Again, all I can say is, using the stock manifolds and the spacer adapters I am really happy. They idle nice and have plenty of top end. To be honest, if my boat went any faster it would be suicide so any thoughts of high rise manifolds or other mods are really out of the question for me.

 

[SeaSkwurrel]

Re: Carburetor replacement

Thanks for all the info-it's a great help!