i have a 1000 cfm 4150 holley marine carb and i was wondering if anyone know if i could jet it down enough to be a 850 cfm ????getting way to much fuel,washed the ring out.if i cant i will sell it and buy a new 850 cfm.

If a carb is too big for engine, you jet it richer because of less signal velocity.

If its way too big, then there is no real solution other than to send it to nickerson for some major work.

What engiine and HP, rpms?????

You cant jet down cfm. CFM is cubic feet per minute. That means how much air CAN flow through the carb. Jets simply set up the mixture of air and fuel. In some cases, you can replace the boosters to larger diameter ones. That will slow the air charge down some, lowering the ability for the carb to flow air. Like sticking a cork in the venturiis.

Hi, How did you come up with an 850 as being the correct size?

Try Tim Zepp. A great carb guy. Built a carb for my 540.
The annual boosters were to big ( not pulling in enough fuel on the top end) The purple ones are a little smaller.

http://timzeppengines.com/index2.htm