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1965 Evinrude 3hp setting points gap

C

Colezay

Regular Contributor
Hi everyone, I have a 1965 Evinrude Yachtwin 3hp model #3532a and I recently took off the points to clean them since they were all corroded. I am wondering how to set the points gap on it since they seemed to be off. I see there is something on the crankshaft labeled “TOP” and I think this has something to do with it? Any help would be appreciated
 
You can set them to 0.020" at the widest point.----You use the little cam screw to adjust them.----Or if you want you can use a meter to get them set exactly at 180 degrees apart .----Using the meter gets them to open at the correct time for the strongest spark.----There are some tutorials online on how to use the meter.-------leroysramblings -----Is one site for that.
 
The lettering stating "Top" indicates the top of the cam, pertaining to cams that might be able to be installed upside down.

Setting the points...... line up the flywheel key with the fiber rubbing portion of whatever point assembly you're going to set (widest setting)... now set the points so that a .020 will slide thru but a .022 will not.

That'll get you as close to a factory setting as one could get.
 
Never knew that, Joe..... thanks. I thought it was there to indicate the highest point on the cam. Some have a little arrow or pointer next to the "top" mark. That is the place where the points are set. Hope your managing the storm okay. My brother in Miami, who is no stranger to big storms (went through Andrew down in Perrine area just south of Miami) he said the rain in this new storm was brutal.
 
Ya setting the points with an ohm meter and the rubbing block at the arrow gets you real close to tdc.
I checked it with a timing light.
I did check what the measurement was when the crankshaft key lines up with the rubbing block, measures at .022".
That .002" difference enough to advance the timing much with setting the points to .020"?
BTW I am working on a 1974 Johnson 4hp.
I picked it up in spring.
Has been a finicky starter, 6 or 7 pulls one day 2 a week later.
Took the carb off and cleaned it.
Cleaned and reset the points.
Put my coil tester on and found I'm getting intermittent spark, tester set at .25".
Just because I could I put a drill on the end of the crankshaft and gave it a spin.
Intermittent spark problem goes away.
Pull start to slow = problem, is this a sign the coils are going?
 
I forgot to mention what I did, I just set it so the flywheel key is facing the part where the points touch. After that I gapped the distance so a 0.020 goes in but a 0.022 doesn’t fit. It now has the strongest spark I’ve ever seen in an engine LOL.
 
Thanks for showing us that bulletin.
Will also reset my points.
I will check the spark at 5/16".
I'll let you know what happens tomorrow.
 
fdrgator said:
Will this help clear up the confusion?
Click to expand...

OK, reset the points to .020" at the crankshaft key.
Checked the timing.
.020" point gap advances the timing to 2 degrees btdc, at .023 the timing is 2 degrees atdc.
I'm new to the 2 stroke world but the 2 engines that I owned before this both have idle timing set atdc.
Any thoughts?2atdc.jpg2btdc.jpg
 
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timguy said:
Never knew that, Joe..... thanks. I thought it was there to indicate the highest point on the cam. Some have a little arrow or pointer next to the "top" mark. That is the place where the points are set. Hope your managing the storm okay. My brother in Miami, who is no stranger to big storms (went through Andrew down in Perrine area just south of Miami) he said the rain in this new storm was brutal.
Click to expand...

I know of what you speak Tim... appreciate having you jog my memory. There does exist two Cams that have the word "TOP" either engraved or in raised lettering, one of which is actually spelled out is lettering size such as #10 as if used in a sentence... and this is the one that the word "TOP" simply indicates which way is "UP".

The other one which you mention, as I remember it, is in smaller print and a very small section is marked on top of the cam as the precise area to have the cam set when adjusting the points. I didn't look to see if I still had them in stock, but drawing on memory, it seems to me that the word "SET" was there in much smaller print on this type cam.
 
Thanks, Joe. I'll be in the shop today and look around at some, got me curious...will post a picture or two.
 
I have one 3hp cam for reserve. This is 3hp cam before 1966. There is letters: TOP, but there is also like small indication arrow just with letter P. I tried to take one photo also. Red indicator arrow should point the indication point, on the cam.
Cam.jpg
 
timguy said:
Thanks, Joe. I'll be in the shop today and look around at some, got me curious...will post a picture or two.
Click to expand...

I have that picture.The difference between setting the points at the arrow, with an ohm meter (2 degrees atdc) and at the crankshaft key, .020" (2 degrees btdc) is noticeable at idle. I can only imagine what is happening at full throttle with 4 degrees of advance added.

arrow.jpg
 
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progolf, as I read and try to understand hat you are saying, I get the idea that you do not understand what's going on here or maybe you are misusing the terms BTDC and ATDC.

So, let's start at the beginning. The whole reason for setting the points in the first place is make them break contact at a certain time as the flywheel magnets pass the coil's laminated pole shoes. As the magnets pass by, a voltage is generated on the coil's primary winding. At a certain position, that voltage reverses and the points open, which causes a series of events which result in a spark. It has nothing at all to do with the timing of the piston +/- TDC. However admittedly it does affect TDC a bit. The whole thing to remember is the point' gap is for the magnets-to coil position, NOT for piston +/- TDC position.

In a perfect world, the points will break at the middle of the two timing marks on the armature plate. That is the intended time of the voltage reversal. New points should break at the first mark and will shift toward the second mark as they wear. That is the only reason for setting the gap in the first place.

Now about +/- TDC which refers to the piston at the top of its stroke. That time varies all over the place as you rotate the armature plate with the throttle. It will be somewhere BTDC at full throttle and somewhere ATDC at idle, or anything in between. BUT---shining a timing light at the armature plate is showing the relationship between the magnets and coil, NOT the relationship of the spark as regards piston stroke.

I dunno, I tried to say this so it will be understood (????)
 
Agreed ----Just set them with the meter as in above post.------It is the best way.----It gets you the strongest spark.-----Takes the guess work ( feeler gauges ) out of the picture.----The timing fixture is nothing but a " dummy flywheel " and it is a factory / shop time saver.-----You can indeed use the flywheel timing marks to set the points with the meter !!
 
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fdrgator said:
progolf, as I read and try to understand hat you are saying, I get the idea that you do not understand what's going on here or maybe you are misusing the terms BTDC and ATDC.

So, let's start at the beginning. The whole reason for setting the points in the first place is make them break contact at a certain time as the flywheel magnets pass the coil's laminated pole shoes. As the magnets pass by, a voltage is generated on the coil's primary winding. At a certain position, that voltage reverses and the points open, which causes a series of events which result in a spark. It has nothing at all to do with the timing of the piston +/- TDC. However admittedly it does affect TDC a bit. The whole thing to remember is the point' gap is for the magnets-to coil position, NOT for piston +/- TDC position.

In a perfect world, the points will break at the middle of the two timing marks on the armature plate. That is the intended time of the voltage reversal. New points should break at the first mark and will shift toward the second mark as they wear. That is the only reason for setting the gap in the first place.

Now about +/- TDC which refers to the piston at the top of its stroke. That time varies all over the place as you rotate the armature plate with the throttle. It will be somewhere BTDC at full throttle and somewhere ATDC at idle, or anything in between. BUT---shining a timing light at the armature plate is showing the relationship between the magnets and coil, NOT the relationship of the spark as regards piston stroke.

I dunno, I tried to say this so it will be understood[/COLOR] (????)
Click to expand...
[/FONT]


LOL
When the points open, as you stated the coil does its job.
Making point gap less (ie. at the crankshaft key) opens the points sooner.
Your 3rd paragraph says that.
Changing when coil does its job is changing the timing.
What do you think moving the cam plate does?
It changes when the points begin to open.
BTW I am using my timing light to see the timing difference between the 2 different point settings, nothing more.
Don't believe me?
Try it.
Set the points with an ohm meter with the rubbing block at the arrow on the cam.
Set the points with the rubbing block at the crankshaft key to .020".
Set the points with the rubbing block at the crankshaft key to .022" or .023" or what ever measurement you want.
The timing changes.
And that has been 1 of my question all along.
Setting the points at the arrow is not the same as setting them at .020" at the crankshaft key.
And there is a noticeable change in the way the engine runs at idle.
 
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Yes....good idea. These are so simple that somehow we must make them more complicated. Wonder what the Wright Bros. would think about the 737 Max and it's MCAS. You know what I think about it? I think it's "bad engineering" to attempt to correct "bad engineering". Kinda like having to turn off your power steering when you most need it to avoid an accident. Brilliant!
 
Also, since the throttle changes the positioning of the ignition plate. What should I set the throttle at before setting the points?
 
Doesn't matter. The points are set in order to sync them with the flywheel magnets passing the coil. There is a certain margin of error allowed. The stator plate....including all spark components, (except plugs, of course), all move together....working together. The amount the timing changes is measured in huge amounts.....so 2 degrees is insignificant.
 
profgolf said:
[/FONT]


LOL
When the points open, as you stated the coil does its job.
Making point gap less (ie. at the crankshaft key) opens the points sooner.
Your 3rd paragraph says that.
Changing when coil does its job is changing the timing.
What do you think moving the cam plate does?
It changes when the points begin to open.
BTW I am using my timing light to see the timing difference between the 2 different point settings, nothing more.
Don't believe me?
Try it.
Set the points with an ohm meter with the rubbing block at the arrow on the cam.
Set the points with the rubbing block at the crankshaft key to .020".
Set the points with the rubbing block at the crankshaft key to .022" or .023" or what ever measurement you want.
The timing changes.
And that has been 1 of my question all along.
Setting the points at the arrow is not the same as setting them at .020" at the crankshaft key.
And there is a noticeable change in the way the engine runs at idle.
Click to expand...


I give up, you and I are saying the same thing. Except you keep referring to TDC which is not the same as opening time in relation to the magnets. And I did say that the points setting affects the advance a bit at wide opening throttle

BTW, I made and sold a few thousand of those timing fixtures. I know what I'm saying, even if others don't.

Over and out.
 
fdrgator said:
I give up, you and I are saying the same thing. Except you keep referring to TDC which is not the same as opening time in relation to the magnets. And I did say that the points setting affects the advance a bit at wide opening throttle. BTW, I made and sold a few thousand of those timing fixtures. I know what I'm saying, even if others don't. Over and out.
Click to expand...

Agreed wholeheartedly about those pointed fixtures Gator... the only way one can get the timing exactly (spark) to take place between the two markings on the armature plate. Unfortunately most boaters don't have access to them.
 
But you can use the flywheel to set the points EXACTLY the same way.-----Just have to lock magplate in position and lift flywheel of to turn the cam screw.---Takes a bit longer but just as accurate.
 
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