I always thought those were the idle mixture screws. I have since upgraded to a holley 4bbl w/offy intake (fantastic upgrade imho)
Anyway,here is the proceedure I use and should be the same for the origional 2bbl
Get a vacuum guage, connect it to manifold vacuum. I think there is a little hole in the back below the carb you can install a fitting in, btw I installed a vacuum guage and just leave it hooked up if you don't want to do that make sure you cap the hole when your done.
Run the boat to operating temp. Adjust one of the screws to peak vacuum, then the other, repeat till you get the best vacuum (15-20 psi), you may need to adjust your idle speed ( on the throttle arm, where the cable connects) check your timing, if you need to adjust the timing repeat adjusting the idle screws, etc untill you have max vacuum (at idle)with proper rpm and your timing is dead on.
It really is easy and does not take much time. And your idle will be set by the most scientific method I have found. Works great for me.
Good luck,
B.C.
------Original Message------
From: jd
Sender: omc-boats-bounces@lists.ultimate.com
To: Evinrude & Johnson Boats of the 1960's and 70's
ReplyTo: Evinrude & Johnson Boats of the 1960's and 70's
Sent: Jun 19, 2009 12:55 PM
Subject: [OMC-Boats] carb question....
so no one knows and/or wants to take a crack at what the two adjusting
screws under the carb actually do? would love to know......so i
don't make things worse by guessing my way through.
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