1966 Evinrude 18hp ignition questions.

[steviecops]

Hi<br />I've just replaced all the ignition parts under the flywheel and fitted new HT leads on my old fastwin. When I got this engine, the old HT leads had been cut, so I don't know which lead goes to the number 1 cylinder.<br /><br />I've tried watching both sets of points and seeing which piston is TDC when the points open, but can't make any sense out of it. Should the points just open, or close when the piston is TDC? On this engine, the piston has already started on the down stroke when the points are just closing. When the open mark on the cam is lined up with the rocker on the points, both pistons are well down in the cylinders. Does that sound right?<br /><br />Is there an easy way of telling which coil goes to which cylinder? I can't see any mention of this in any of my manuals. My instinct is telling me that the coil with the longer HT lead, (ie, the one which runs around the timer base), should go to number 1 cylinder.<br /><br />Any info would be greatly appreciated.<br /><br />Thanks in advance.<br />Steve

 

[Paul Moir]

Re: 1966 Evinrude 18hp ignition questions.

Spark happens when the points just open. The ignition coil at the front or front-port of the engine runs the top cylinder. The longer leaded coil (the back or back-starboard) coil runs the bottom cylinder.<br />Spark at TDC occurs around the 'Start' position on the throttle.<br /><br />Hope this explains it! Good luck!<br /><br />EDIT: I just double checked this on an outboard sitting here. By the way, there's two marks on the armature plate just below the front coil. There is also two marks 180° apart on the flywheel. If you put a timing light on a spark plug lead and crank the engine, the mark on the flywheel will appear between the two marks on the armature plate if you have your points set correctly.

 

[R.Johnson]

Re: 1966 Evinrude 18hp ignition questions.

Looking at the engine from the front, the set of points to the left on the stator plate goes to the #2 cylinder. When the key on the cam is in line with the rubbing block on the points, they should be open at .020. Thats why the pistons look out of postion if you go by the key. When you get this magneto correct, it is very reliable, and has very good output. Make sure you use wire core leads on the coils, not resistor wire.

 

[Tinkerer]

Re: 1966 Evinrude 18hp ignition questions.

Don't know your motor but here's some general principles that might help.<br /><br />Ignition occurs a bit before TDC so the piston will still be on the way up when the points start to open. <br /><br />It's very hard to see the points begin to open. By the time it's visible there's already been a bit of movement in the points and piston. It's easier to do it with a multimeter with an audible signal; or a test light; or the old way with a cigarette paper put between the points and held tight - it'll pull out almost the moment the points begin to open. The piston should still be a fraction below TDC on the compression stroke when the points open.

 

[steviecops]

Re: 1966 Evinrude 18hp ignition questions.

Thank you for the great advice. They were very good, clear explainations and it now make sense to me ! <br /><br />R.Johnson, That'll explain it then!, and yes, I did use wire core HT leads. <br /><br />Thanks again. Much appreciated.<br />Steve

 

[Chinewalker]

Re: 1966 Evinrude 18hp ignition questions.

NOTE: This is true for all OMCs using the traditional 2-coils-under-the-flywheel magneto... The FRONT coil fires the TOP cylinder... The works with the set of points directly COUNTERCLOCKWISE to the coil.<br />- Scott