Carb question for a 76 Evinrude

[Fiddlefire]

I was looking in the carb section of the card needle adjustments for assorted carb variations by Joe Reves. My motor has 3 carbs that does not seem to be mentioned. It also says on top that it does not cover fixed jet outboards. I'm still a bit new to this and I am wondering if there are any adjustments at all on these carbs. My motor is a 70EL76D. I was looking in what I believe is called marine engine .com that has the entire breakdown of my motor for reference and the only thing that may look adjustable is the idle passage screw. Is this carburetor system being used called a fixed jet carburetor?? I rebuilt all 3 carbs and that screw I took out on each one, cleaned out and soaked over night and a new gasket installed that came with the carb rebuild kits. I guess that one of the things that I am asking as well is that screw a low idle adjustment??

 

[Chinewalker]

Your motor has fixed jets - nothing to adjust, mixture wise. That screw you're referring to above the carb throat is a plug, not an adjustment...

 

[heypawpaw]

You have a fixed jet carbs, look at carb parts diagram # 27 and #35 low and high speed orifice (brass fitting with a metered hole, no adjustment.) High speed is on bottom. The parts you removed and installed new gaskets on are plugs covering the orifices. On adjustable carbs instead of plugs, there is a threaded needle. Look up 1966 Johnson 20 hp model # FD20 for look at an adjustable carb.

 

[Fiddlefire]

Okay, between both responses this makes a lot of sense to me. A had a couple of friends of mine iquiring about adjustment. When I pulled that screw out during the rebuild process I didn't seem to think that the screw was an adjustment. This has been very knowledgeable and useful information for me and thanks very much!

 

[Fiddlefire]

Someone on one of my other blogs mentioned an old service bulletin on carb mods that use to make them have much better performance. Has anyone heard of this? I am going to try and research this on line to see if something comes up.