what are under the caps on the baseplate of a merc 2bbl?

[89sandman]

my 85 has a single air/fuel mixture screw on the baseplate to either side of the screw is a cap. are these idle jets or idle air/flow screws. i just rebuilt the carb and everything works perfect except for i still have to give it a little throttle now and then to get it to start and the idle is not as smooth as i would like it. if they are idle jets would like to pull and clean them if they are idle air/fuel would like to richen them to smooth out my idle...

 

[wellcraft-classic210]

Re: what are under the caps on the baseplate of a merc 2bbl?

That screw is your idle mixture FUEL adjutment. Adjusting the single screw allows more or less fuel to flow by changing ther passage size at the screw tip. ( out is richer )

These can be set as follows;

With a warm engine turn the screw till she runs the smoothest at idle // then rougher in both directions // then split the difference.

Air mixture is set by the throttle plate stop screw-- it sets the idle speed. This may also need to be adjusted once you get the mixture set.

Not sure about the caps you are referring to in you heading. Perhaps one of the experts here will know. If not you may want to post a pic & add a detailed description.

 

[89sandman]

Re: what are under the caps on the baseplate of a merc 2bbl?

i'm wondering if they are caps for the 2 fuel air/screws if its made into a rochester instead of a mercruiser???

still trying to find a new carb replacement for this thing that isn't made of gold anyone ever put one of the 2 barrel holly carbs on a 3.0l???

 

[Don S]

Re: what are under the caps on the baseplate of a merc 2bbl?

You might want to post some pictures of your carb, Mercruiser doesn't use Holly carbs nor did they use them in the 80's.

 

[achris]

Re: what are under the caps on the baseplate of a merc 2bbl?

...still trying to find a new carb replacement for this thing that isn't made of gold anyone ever put one of the 2 barrel holly carbs on a 3.0l???

DON'T use a Holley.... They are rubbish on boats... Merc stopped using them in the 70s...

Have a look here -> http://www.i-5automotive.com/marine/

Chris......

 

[89sandman]

Re: what are under the caps on the baseplate of a merc 2bbl?

chris i actually came across them when i was cruizing the net and gave them a call. the problem is they are a rebuilt unit. the only new option i've found that isn't almost a grand is the holley. the price of the holley even with an electric choke kit is not even $100 more. back in the day when cars still had carbs had installed the holley (non marine) on several cars and trucks they worked just as a new carb should. had the same problem with them, no other new option. don't really want to keep messing with rebuilt if there is any new option that is near the price. read somewhere about maybe being able to adapt a weber... sure wish efi wasn't a 3-4k deal!!!

 

[achris]

Re: what are under the caps on the baseplate of a merc 2bbl?

... back in the day when cars still had carbs had installed the holley (non marine) on several cars and trucks they worked just as a new carb should. ...

On cars, yeah no problem, but Holleys don't work well at low revs with high demand.. like a boat at take off.... Cars get round that problem with a gearbox.... No such option on boats.

4 bbl Weber on a 3.0L... THAT I would love to see... (Bit overkill me thinks)....

Chris........