Carb adjustment

ericcarr2000

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
I just recently purchased a new carburetor for my 3.7 mercruiser and was wondering if anyone out there could give me some tips on how to adjust the thing, like setting the choke and adjusting the air/fuel ratio. It is for a two barrell carb that has the two mixture screws on it.
 
04fxdwgi

04fxdwgi

Senior Chief Petty Officer
Joined
Jun 10, 2011
Messages
754
Re: Carb adjustment

If you have the manual, it should spell it out for you. If you don't have one, try downloading a copy. The adjustments for the choke are pretty specific from engine to engine.

I can send a PDF I have of the 2 bbl rebuild / adjustment from Merc, but it's an 8 meg file. Too big for here. if you want, send me your e-mail via pvt message and I'll e-mail to you. But it's for the V-8 engines, but it will give you the general gist.

As far as mixture goes, you can do an initial to get her idling smooth out of the water, but should be adjusted while in the water (preferably tied to the dock) and in gear for smooth idle. That's in the PDF also.
 
D

dccordell

Chief Petty Officer
Joined
Apr 28, 2010
Messages
415
Re: Carb adjustment

Go to the Adults Only sticky at the top and click on Mercruiser Info, then Manuals. Depending on your year, I think you need either #3 or #8. I have a '79 model and I use #3. It is a BIG file, so while you're downloading that, here is a couple shots of the page dealing with adjustment of the two screws... hope you can read the small print (the print is bigger in the actual manual). The manual has the stuff for the choke too...

Page 1
carbadjust1.jpg

Page 2
carbadjust2.jpg
 
superbenk

superbenk

Commander
Joined
Oct 27, 2008
Messages
2,022
Re: Carb adjustment

dccordell said:
Go to the Adults Only sticky at the top and click on Mercruiser Info, then Manuals.
Click to expand...

manuals aren't here anymore.

04fx had it with the idle mix. There's a difference between out of the water & in the water. It'll take some fine tuning over time to get it just right. I think choke adjustment wants about a 1/64 - 1/32 inch gap when closed, but as has been stated, it's probably different for different engines. Carb didn't come with adjustment instructions? My rebuild kits did.
 
ericcarr2000

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
Re: Carb adjustment

I purchased a rebuilt carb from a carb shop online, so I really dont have anyinstructions for it. Thanks for the info regarding the manuals.
superbenk said:
manuals aren't here anymore.

04fx had it with the idle mix. There's a difference between out of the water & in the water. It'll take some fine tuning over time to get it just right. I think choke adjustment wants about a 1/64 - 1/32 inch gap when closed, but as has been stated, it's probably different for different engines. Carb didn't come with adjustment instructions? My rebuild kits did.
Click to expand...
 
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