Idle speed and tach

[brielly]

Well I finally got the bottom of my engine troubles. Upon rebuilding the carbs I found the bottom one was completely gummed up. I got them back together fired it up and it was idling very high. I turned the speed screw and got it down but now its running rough. I may need to mess with mixture next but the real problem is I have no idea what rpm's its currently idling at. I tried a multimeter with tach attachment but got no reading. I have an older style automotive tach with alligator clips but I have no idea what to hook it up to to get a reading. Can anyone tell me where to connect it? Thanks!

 

[emckelvy]

Re: Idle speed and tach

Unless you have a very old Inline Six with points ign and dual automotive coils, an automobile tach ain't gonna work.

What you need is a Marine-Type tach, which takes a signal from the output of the outboard's alternator.

The tach's signal wire will connect to either one of the two yellow stator wires which are hooked up to screw terminals of the rectifier.

You can find tachs for outboards at this site's store, eBay, or any number of marine stores online or locally. Look for one with settings for a 12-pole alternator.

BTW, you don't really really have to have a tach to set idle, the motor should be adjusted to idle as smoothly slowly as possible, but not too low that it'll die out when shifted into gear in the water.

This of course means you'll need to make your final adjustments in the water in gear. You can simulate this if you can fit the motor in a 55-gal barrel. One of those large plastic water barrels works well as they're easier to work around the motor than a metal barrel. Just be sure the prop doesn't hit the bottom or sides of the barrel when running, or you'll need a very large hose to fill it!

HTH.........ed