carb for 521

what size carb should i run on my 521 and what is better alcohol or gas

what are you using it for?

Figureing a 7000 RPM peak, 521 cu in, ideal carb would be about 1200 cfm capable.

If your build is limited down to about 5000 RPM peak, then a 950 is fine.

In my opinion if you want to go the alcohol route, avoid the carberator all together. If you seriously plan to have the benefits of alcohol, go with an injection system, something like a flying toilet or that nature. The volume of alcohol required, carbs just don't deliver as well as injection.

alky and carbs work good....... to a point, and it depends on the carb also, not all are created equal.

you are right everything has limitations, but when coupling bigger displacement, with high RPM. You simply cant move the volume of alcohol needed.

1050 APD on my 529 worked great, inj was only worth a tenth in the 1/4 over it, both plain meth and M5................I'm sure on this 563 it would be a diff story but I never made the swap back to a carb so I dont know. Carb was a lot less hassel IMO.

Again it depends on what its going on and its intended use.

it is going on a mud race truck

1050 or 1150 Gas Dominator would be my choice.

Alky is a PITA.

thanks alot for the info would you do a prosystems carb or a quick fuel or just a holley dominator and what about Q16 fuel

I like Quick Fuel Products for an out of the box carb, Pro Systems is some damn fine stuff too.

Q16 is good if your engine requires the octane and you can afford to run it.

i have been running george rupert carbs for the last three years and two of them have been on alcohol i am thinking about trying the Q16 i have heard that it will make more power ?

I'm a Gas guy.... With a Carb on a big engine gas will make more power from what I've seen