Reply To: 1973 6Hp Evinrude Fisherman hard starting cold

[Tom Bertulli]

Hi Fleetwin,
When I installed the offset key and got no change in performance I Removed it and re-installed the OEM key which has been in place throughout our thread here. The key in the picture is not sheared, but intentionally “carved:” that way to create an offset between the crankshaft keyway and the flywheel keyway by a couple of degrees. Install the offset key one way and it will retard the spark timing. Install the key in reverse position (upside down) and it advances the spark timing. I wish I could show you a diagram because a picture is worth 1000 words and you would see what I mean right away. With respect to the spark timing as it is now, with the original key and new modules- let me describe & bear with me because I’m not trying to be condecending. I don’t know how to send simple diagrams over the internet. I drew a crude picture – see below attachments. Picture in your mind or draw on paper the mag plate with the two timing marks in front of you. There will be a vertical line on the left and a similar line on the right about 1/2 inch apart. Half way between these two marks is perfect timing. If points are set perfectly, a timing light will show the boss mark on the flywheel to be in the centre between ( but above) the two lower timing marks on the mag plate on each revolution of the crankshaft. With the modules and OEM key, the timing light shows the spark firing when the boss mark on the flywheel is exactly over top of the right hand mark on the mag plate. I assume, without knowing for sure, that the spark is somewhat retarded. So my questions are as follows.

1 by the picture #1 below, when the spark fires, which direction on the mag plate indicates an advanced spark, to the right or left of the double timing marks?

2 If I remove the key completely, can I alter the spark timing by clocking the flywheel keyway to the right or left of the crankshaft keyway? (I would test at low speed in a barrel for starting & running improvements after warm up. If a significant improvement is found I would have to find a way of securing the new crank & flywheel relationship without a woodruff key).

3 by the picture #2 below, If I wish to advance the spark, should I rotate the flywheel keyway clockwise or counter clockwise from the crankshaft keyway?

4 How much should I rotate the flywheel? IE If Flywheel & crankshaft keyways line up at 12 oclock, should my first movement of the flywheel be to 1 oclock, 2 oclock, 11’30 oclock??

To Crosbyman – I have adjusted the cam & follower as you suggested. Some minor improvements to starting. Cold start 3 pulls at about 5/8 throttle with choke. Warm start no choke, 1 pull at about 1/2 – 5/8 throttle. Thanks. I think we are at the limit to what carb & fuel adjustments will do, that’s why I’m exploring timing as an issue. Another rabbit! I’ve given up on the reed valve theory.
thanks in advance, Tom