70 3 cyl choice: idle or accelerate

[SeaHorse]

The book says to set the idle air screw on the carbs(2) to 1.5 turns out. When I do this, the motor idles quite roughly but accelerates ok. If I idle the motor after warmup in gear then screw in (to about 1/2 turn out) the carb idle air screws until the motor speeds up and idles quite smoothly, but it dies if I try to accelerate. Then I have to back out the settings to too rich again (poor idle) to accelerate again. <br /> Plugs are good, I have used Seafoam, new fuel diaphram but carbs have not been touched since dear-knows-when (just got the motor this year). Motor is 1979 700 with 80's electronics.

 

[The Marine Doctor]

Re: 70 3 cyl choice: idle or accelerate

Here is another thing you might notice...when you have the screws set to 1.5 where they should be and increase the idle...then engine will smoothen out.<br /><br />The engine needs the extra fuel because of the design of the carb. It does not have an intermediate jet to supply fuel just off idle.<br /><br />So what we do is increase the amount of fuel at idle to compensate for this until fuel is drawn from the high speed tube.<br /><br />They can only run so slow.<br /><br />TMD