with the new heads, the guy who helped me build the motor didnt think it would be enough.

 

im tellin ya, grab a 625/650 Demon carb and you'll be a happy camper

 

302 cubic inch motorat 100% efficiency can use 524.3 cubic feet of air at sea level.
So you engine is most likely NOT 100% efficient and therefore would be actually hurting performance with a bigger than 550 cfm carb.

1 cubic foot is 12 X 12 X 12 inches or 1728 cubic inches in a cubic foot.
302 cubic inches at 6,000 RPM would be 302 X 6000 = 1812000
Then because there are only 1/2 that amount of intake strokes on a 4 stroke engine you would have to 1/2 that number or,
1812000 / 2 = 906000 Cubic inches of air at 6000 rpm
906000 / 1728 (cubic inches in 1 cubic foot) = 524.3 Cubic feet of air.

Any carb that delivers 550 cubic feet of air is all your engine can ever take, unless you stuff it in with a blower/ turbo/ Nitrous. .

 

It seems to me that the 600 is plenty of carb for that engine. Here, calculate it yourself.
http://www.csgnetwork.com/cfmcalc.html

 

This does the math for you and it actually came out to what I put in the above post.


[IMG]local://upfiles/58274/DD22708E76A8492BB794379A376A89D3.jpg[/IMG]

 

this is the part where i fall back to the "your only running on two barrels half the time" arguement. YES mathmatically they cant handle 600 cfm, dont you think carrol shelby knew this when he was bolting on 780 cfm double pumpers to 289's? now 780 is way too big for my tastes, but it goes to show theres a reason people go bigger than what the motor can mathmatically handle. theres a reason when you talk to BG or holley or any other carb manufacturer they will tell you to use a bigger carb than you would think from looking at numbers. dont you think these people know what works and what doesnt?