Been searching but having problems with finding an answer.

Have stock 502 merc crate 425. Carb is a holly HP 4150 with number 80558 on the side. Think it is a 830cfm. I know this thing is not tuned in properly and would like to do some adjustments because it is running rich. (leaving some black on the back of my boat) Also, every once in a while the engine will flood out and will have to wait for it to air out.

Went to http://www.mortec.com/carbs.htm and they have some good info, but is my carb too big for my current set up? Can I jet it down to be the right size? Does any one have any jet size recommendation for my engine? What about power valves, does this carb have one installed?

thanks,

jon

Any good book I can buy on holly carbs?

if its is a 830 you should be fine. Hows your ignition system /wires ect.? Holleys tend to run rich down low. if its carb issues you can get a book@ summit racing.

Carb size is fine.

When is it rich???????? idle???? WOT????