I am currently looking for a good replacement 4-bbl. carburetor for my Original 1965 Mustang GT. It has less than 42 K actual miles, and I am the 3rd owner, but whoever had it before me put a Tomco carb on it that has been being worked on, but is leaking gas into the exhaust manifold. It has the 289 V-8 A-code motor and the original car had an Autolite 4100 570 cfm, manual choke, 1.08 venturi, vacuum secondary carb. I'm being told to find something in the 570-600 cfm range, but I'm having trouble finding anything that is not high performance (been looking around for a couple days and finding Holleys, Edelbrocks, Carters, etc.) Plus, I don't know that I need high performance nor do I necessarily want to pay the price for same in both bucks and gas mileage.
Anyone know of any other options or got any suggestions on any good sources or any other way to go?

 

Since your car/motor is likely mostly original, I see no reason to deviate from the factory Autolite 4100 (which is ~480CFM, not 570). They're super simple, very reliable, and will work just fine.

Sure, you could go with an aftermarket carb (although I'd recommend 500-525CFM), but you'd have to tune it to your motor and it wouldn't be factory correct.

If you look, you can find rebuildable 4100's on ebay for under $100. As long as they're not missing parts and the throttle plates and rods don't have a lot of slop in them, rebuilding them is very easy. The only costs would be a rebuild kit and a gallon of chem-tool.

 

These turn up on eBay all the time, just be patient and find the correct one for your car. The 4100 4V was probably the best street carb ever made.

 

Just a note; I learned yesterday that the 66 and 65 carbs are different. The 66 runs a filter on the carb and the 65 runs the filter on the pump. The 65 carb fuel inlet will have a seat in the hole to accept a double flare line. The 66 will not have this and will be threaded to accept the stock fuel filter. Thought that might be useful info for you. You can get these carbs at Pony Carbs but they are pricy.

 

Actually, there were two filters in 66. The early carbs were carryovers from 65, with the inverted flare, while the later ones had a pipe thread. You can get the "on carb" filter either way, so it won't be an issue whatever you get.