A question about point gap and timing mark

[joecb]

Well Mr. Rudderless, I believe that you get the gold star.  Friend Mark and I have been fighting this for the last several days, in and out of the test tank, flywheel off and on, new points and still the same issue. Points all set perfect “on the marks” , good spark when pulled over. But when we start it in the tank, the top cylinder cuts out at low and medium speed. At high speed we get spark, but the timing light shows timing bouncing all over the “marks” . I finally put a dial indicator on the crank.. bad news .013 lateral movement… that is what is bouncing the points around. Funny thing is that it only affects the top cyl points , the lower cyl points consistently hold good to the timing marks???

The motor is a 1969 , Evinrude 9.5 HP “turtle motor” . The top bearing is a needle roller, I can’t image how that type bearing can have that much slop and apparently remain intact.  I checked another similar power head and see only .003 lateral movement.

Joe B

 

[rudderless]

The magnet on the lower is holding the crank in the run position so it stays..the mag for the upper holds the crack opposite the run position..been there..

[Buccaneer]

With that much lateral movement, wouldn’t you be able to feel it
when trying to move the crankshaft side to side by hand?

Prepare to be boarded!

[joecb]

Bucc, yes you sure can feel it, even her it “clicking” . When you think about it, with .013 slop , that would move the points from .033 to .007.

Joe B

[fleetwin]

It is near impossible to set up many of these engines perfectly with the tool/ohmmeter/light, when there is a stack up of slop.  A new engine is one thing, but a well used engine will have a sloppy mag plate, a little bit of crank clearance.  Sometimes just tightening the point retaining screw affects the gap slightly.  We do our best to make it perfect,  but age and wear are working against us…

It is so frustrating to set it up perfectly statically, only to see things out of whack when it is running….  You can always go in through the inspection cover on the old flywheels to readjust slightly to compensate a bit for normal wear.

[crosbyman]

have you tried setting  the points… “out of wack”   to see if they will line up  for running ????   leave the good one adjusted  to TDC  and compensate for the other set.

 

with so much wiggle   are you not getting   blow out of  fuel/oil  ?

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