MerCruiser 3.0 Carb Base Gasket

[searaysherry96]

I replaced the carb base gasket from the two hole thin one to the thicker one hole. It made a big difference in the mixture screw setting. With the two hole thin one, I had to back the mixture screw out 3 1/2 turns to smooth it out. Thick one, 1 1/2 turns out,and ran great just like what is recommended. It wasn't leaking sprayed carb cleaner to check for leaks.

96 3.0lx

Anybody know why?

 

[alldodge]

Re: MerCruiser 3.0 Carb Base Gasket

My first thought is the air/fuel mixture needed enrichment due to 3 1/2 turns out. Don't know why it didn't need that originally, but maybe it did but due to a leaking gasket (which should cause a more lean mixture) the screw was turned in. You also moved the thick one out, which should be the idle adjust screw I take it? If the Mixture was to lean the idle would need to be increased to help overcome the issue. Either way it appears your leak and or something else has been fix by the removal and reinstall of the carb.

 

[jimbo1229]

Re: MerCruiser 3.0 Carb Base Gasket

I might do this myself to help my issue as well if I cant figure it out, trace all the steps back to the carb

 

[schiker]

Re: MerCruiser 3.0 Carb Base Gasket

I would guess a bit of turbulence or the diffusion or slight block of the vacuum around the "barrel divider" that causes a difference in air velocity and hence vacuum on the adjustment needle.

 

[searaysherry96]

Re: MerCruiser 3.0 Carb Base Gasket

Thanks guys, I should point out it was after a professional rebuild.

 

[scooter1961]

i have a 3.0 mercruiser and the base gasket ( 2 hole) is too thin it seems, I'm wondering if i can just double up ??just put a little form a gasket between the gaskets