Logo
FULL SITE MENU

Carb Adjustments

G

golfprorob

New member
Just replaced my 305/5.0 -220hp Mercrusier with a 350/5.7 300 hp. Started with long block and switched everything over. The carb was adjusted for the original engine. How do I go about adjusting the carburetor for the new/bigger engine? Or, do you think it needs adjusting? I've ran it and it acts as if it is looking for more fuel. Thanks for any help you can provide.
 
I have not. Wasn't sure if there were certain adjustments that I could make. Such as tighten screw all the way and back out 4.5 turns etc..

Is it just a matter of trial and error.

Thanks
 
I don`t believe that the screws will do anything other than adjust idle mixture. If the 357 motor is looking for more fuel then you would probably need to pull top off carb and replace jets with larger ones. BUT, that will not help if the engine is also not getting enough air. You can try rejetting but don`t be surprised if you end up needing a larger cfm carb.
 
Here's where i can get in trouble cause it's real red neck shade tree chit.

The difference in jet size is a hair.

So what do you do when you need to have a hole a hair bigger ?

You sure you got the carb tighten down enough and there is no leaks around the base.

Spray wd 40 around the base of the carb.

Hear the motor run different. ?

Want to do a vacuum test, see if there is another problem maybe causing you to believe you need more fuel moving thru the carb.

On Fire vacuum gage

How to Use and Interpret a Vacuum Gauge

You sure to set up the valves right ?

Please don't get insulted, angry or think i don't respect you just thinking out loud.
 
listen two chief, he has a point. think about this you buy new carb,for a 5.0 or 5.7 bolt it on and go no problems, maybe give u something to think about. just my two cents. good luck
 
Back
Top