[Dawgs10]

Ok, the engine is a 289. I need a 4 barrel carb. The previous one was a Holley. I liked it so I figured go with a Holly again. Will most 4 barrel Holley's work with my 66 mustang?

[70Mach03]

If your previous Holley mounted on your present 4-barrel intake manifold, then most any Holley wll fit other that the "spreadbores", which are mostly for GM's.

I recently swapped out my 600 CFM Holley model 1850 for Holley's new Street Avenger 670 CFM and was very pleased in the improvement. Good luck

[BadlandsGhost]

If your cars stock, or near so, you would have better results with a smaller carb, on the 289 600 cfm is about as high as you should go for a stock/mild engine. Anything more, and your going to be overcarbing the engine, have carb tuning headaches, poor throttle response, etc. According to formula, 500 cfm is about where a near stock 289 should be.
As to type, any square-bore (all 4 holes same size) should work, Holley, Edlebrock, Barry Grant, all make street carbs that'd work for you. Not to mention the humble Autolite, which many swear by.
For a street car, make sure its a vac secondary, double pumpers are harder to tune. Electric choke is a good thing too.
Hope it helps,
J

[Yleefox]

Ah, Mr. Ghost speaks wisely. Great advice.

Yleefox.