Normal means stock and stock was probably around 400 cfm or so, maybe 450.

 

Stock 289's with Autolite/Motorcraft 4100 (up until 67 when the 4300 was introduced for polution stuff) were rated between 470-480 CFM. You may or may not be overcarbureted depending on what performance parts were added. Check the oil and see if you can smell gas in the oil. If not, then you are probably not overcarbureted, but just need to tweak the engine for a better tune.

 

For $30 you can have a sample of your oil tested and excessive fuel will show up if its a problem. I was over carbed with excessive fuel in the oil but could not smell it...

http://www.oaitesting.com/

 

I don't have anyway to take a sound clip of my engine, because I can't get it to my computer, but it sounds just like any other stock engine you would have heard. Very smooth just sitting there idiling.

 

In another forum i was told by some guys that 600 cfm is fine for a 289. You just have to tune it really well.

 

Better to run rich than too lean. An oxygen sensor and guage is the only real way to know this, since no matter the cfm rating, you can have too much or too little fuel in the mix. CFM is how much air it will flow, not how much fuel. Fuel is controled many ways in a carb depending on idle, WOT or in between circuits. Oil analysis may indicate only if too much fuel is unburnt, not the other way around. Too lean leads to overheating the exhaust tract.

 

That is what they told me to do. Except i was told EXACTLY what to do.

 

You'd be amazed what google will get you. I wouldn't depend on forum members to supply all the information in one reply...
I found a good carb tuning site the other day, but the link is on another computer.

 

+1
Good research involves more than one source...

 

first off, Shelby used 715 CFM Holleys, but the can and intake were different, plus Shelby's had headers (65-66)....as for a 600, it should be finewith minor mods. My brother has a 750 on his 331 with AFR's, it really depends on how the engine was built