Ok so I'm new here, first post. Quick question.....am I nuts? Is there no clear place to get carb size requirements? Seems like every calculator I use gives me a different answer. I'm having a 383 built that's turning about 425hp and 450ft torque. The builder said a 750 eldebrock right out of the box would be fine. Not a fan. So I was thinking of going with a Holley 770 Marine Avenger, or a AED 750 http://www.aedperformance.com/compon...product_id,63/
However when I use carb calculators it's telling me I need 650cfm. So what's the deal? Can anybody shed some light on this. Sorry I know this is probably a total newb question.

Don't sweat the carb calculators.

You are correct. Dual plane intake def go with 750.

SB is wise...I tried to use the "correct" CFM in my 383. I bought a Quickfuel 750 last month. Can't wait to run it.

My brother has been running the Edelbrock 750 marine carb on his 383 for years without a single problem, http://www.edelbrock.com/automotive/...s/marine.shtml

For not super H/P setups the edelbrocks do work very well, and the elect choke setups are great(they do not like to start with a choke) never seen a 750vs750 test but would love to see that. Mopars back in the day make great HP with AFB's which is what edelbrocks are nowdays

the carb calculator is probably for street engines. you put your Camaro with 425 hp 383 at full throttle. inside of 5 seconds you are breaking every speed limit in the land. then you and your car spend 90% of the time at 10 to 25% throttle. a boat is closer to a big truck than a high perf car as far as the way the engine is run.