Logo
FULL SITE MENU

Carborater Adjustment 1978 305

M

MikeWA

New member
It's been along time (about 45 years), since I had to adjust a carborator. Now I need to do it . I have a 1978 Marquie with a mercusier 898, 305 Chevy. The engione has a Rodchester 2bbl with 2 adjustment screws. Anyone help me?
 
Re: Carborater Adjustment

1. if engine will idle low say 400 to 500 rpm in neutral then adjust main idle screw to that rpms.

Turn one of the air fuel screws at a time and turn it in Clockwise) slowly until engine stumbles slightly. Once that occurrs turn slowly C'clockwise until you reach max smooth rpm. Then repeat for other air fuel screw.

Once you have reached a smooth max rpm then re adjust main idle screw for ~ 700 rpms in neutral.

Done.

If the motor will not idle down to ~ 400-500 rpms then you have a issue!!
 
Re: Carborater Adjustment

Ghost gave it to you straight, i'm just adding a little.

Final adjustment is in the water warm motor in gear, 500-600 is great , 650 is ok and 700 is a little high. You loose rpm on the water you will see...

On the trailer 700 - 800 ok but on the water is where it counts. Timing also, final on the water bring the tools.

Good luck, it's like getting l--d might have been a while but you never forget how.
 
Re: Carborater Adjustment

Like Chief said make sure your timing is correct before adjusting the carb.

But I disagree with Cheif about getting l--d, you might not forget how but you might forget how to do it right! :) It will take a couple tries to do that.
 
Re: Carborater Adjustment

MikeWA said:
It's been along time (about 45 years), since I had to adjust a carborator. Now I need to do it . I have a 1978 Marquie with a mercusier 898, 305 Chevy. The engione has a Rodchester 2bbl with 2 adjustment screws. Anyone help me?
Click to expand...

I use a vacuum guage when adjusting ..carb on any engine.

you will see just how good the engine condition is as well as low vacuum ...most times carb needs adjusting because its dirty/worn parts/vacuum leaks...

before adjusting make sure no leaks..
 
Back
Top