Breaker Points

[Arkman]

Can anyone tell me how the points in my 68' 20hp Mercury work. I know nothing about them and I'm trying to troubleshoot my issues. Should the gap stay consistent on the points as the shaft turns? Or does one point close and one point open as it turns? How do I properly set the gap on the point? I know what its supposed to be, just don't know how to set it.

Thanks!

 

[Fuzzytbay]

Re: Breaker Points

Setting the point gap is fairly easy, once you have done it a couple times.
The gap is set on the high point of the cam lobe. In other words the gap is set at the point where they open. On the point there will be a set screw, this screw is first lossened, then the gap is set using "feeler gauges" of the right gap. I have no clue on your gap, for that motor. Set the gap, so that the "gauge' just slids between the point, with a slight drag. You set the screw so the point holds it posistion, yet can be moved. Then use the correct gauge, set the gap, then tighten the screw, and retest the gap. Sometimes the tighting of the screw will, change the gap. If you try it a couple times, you should get the feel of it. That being said, also check to make sure the points are not "burnt". The two opposing surface's should be smooth, with no pits, or burn marks. If there are marks, you have to file the points smooth, with a point file, or if they are too badly pitted, etc, replace them completely. If you do have to replace the points, replace the capacitors too. Those are the silver "canisters" usually right beside the point, with a black wire running to one of the screws on the point.

 

[Arkman]

Re: Breaker Points

where do i get a point file. I know that i have to replace it because one wont hold any gap...the spring part is shot. I can't find the condensers in town, is it possible to just do the point or is it critical to do the condenser? If it is I can just wait to order it online.

Thanks!

 

[JB]

Re: Breaker Points

Condensors are either good or bad for the most part, Arkman. They really fit the saying, "If it ain't broke, don't fix it."

If you have doubts, however, they are cheap and a snap to replace.

 

[Arkman]

Re: Breaker Points

So if I replace the points can I try the motor and if it works I'm good or will a bad condenser hurt my points?

 

[green4themoney]

Re: Breaker Points

condensers are basically layers of waxed paper and metal foil wrapped up together in a cylinder that hold a temporary charge untill the breaker points open and release the charge into the secondary coil winding, on the maker points its direct contrast to the breaker points, the points in this case are used to open and close the electrical circuit, you have the breaker points but if you had a 1970 nand up you have the phase maker point system.

 

[Arkman]

Re: Breaker Points

I bought some points off of ebay a while ago, but didn't put them in because I think they are the wrong part. The little tab that touches the crank shaft(right word?) is a little shorter then on my old point, by maybe 1/16th of an inch. This made it so I couldn't pull the points far enough apart, I could only get 012 instead of 020 which is what I need.

After some tinkering I discovered that the washer on the screw was hitting the point and pushing it closed when I screwed it tight. I adjusted the washer and have a "perfect" gap (as good as I can get it). I slide the feeler gauge in and there is a slight amount of pressure but not a lot.

Is it ok to use these points? They look 99% identical, the only difference is that that little tab that touches the shaft was a 1/16 too short.

 

[Fuzzytbay]

Re: Breaker Points

The shorter throw on the points may affect the dwell angle slightly, I'd try them, if the gaps correct, it shouldn't cause the timing to be too advanced.
You might want to get other oppinons though, before you try it.

 

[green4themoney]

Re: Breaker Points

your talking about the cam follower right? that is pushed upon by the lobe on the crankshaft that opens and closes the points? if your original cam followers were a wee bit shorter that may be from simple wear, as long as you can get 0.020 for your gap and you line them up properly and theyseem to fit ok, give em a try... what engine are they on anyways?

 

[green4themoney]

Re: Breaker Points

by the way man, your motor ('68 merc 20 hp) point gap is set at 0.020 so you need a feeler guage, and make sure you set your gap at the HIGH side of the cam (so make sure your cam follower is touching the high side to adjust that point then follow the same procedure for your other point

 

[Arkman]

Re: Breaker Points

The old points had a longer part. The new ones are a bit shorter, but only a small bit. I did what you said, got the point right at the high point. Everything seems to be the same as the old point other then the part that touches the crank shaft.

If I do try it, can I hurt the motor if its incorrect, or will I just get no spark? I talked to a mechanic thats a friend of mine and he told me as long as the gap is right it should be fine. Thoughts?

Thanks!

 

[Fuzzytbay]

Re: Breaker Points

Points require two settings, first one is the actual gap, the second is how long it takes to open and close. You have first correct, now the second one is called the "dwell angle". If the dwell angle is not right, it will affect idle, and lower speeds, once the engine is up at 5500 rpm,(what ever your top rpm is)it really doesn't matter much if the dwell is off a couple of degrees. You can adjust the dwell angle, by moving the point, out from the cam. or by moving it in. I am pretty sure your points don't have a "fixed" dwell. I'd try it and see. If you have major idle problems, and can't get the idle set, or its too high, and bangs when it goes into gear, then maybe they won't work. Or maybe you have to adjust the points possition, in relation to the cam. It shouldn't 'blow your motor up though".

 

[Arkman]

Re: Breaker Points

I got spark! I got home and replaced the condensers and put it all back together and gave it a test pull to see and there was a really nice strong looking spark. As long as no one else thinks its a bad think I will test it this weekend. I'm crossing my fingers. It's been a real struggle to get points.

Thanks for the advise!

 

[JGra]

Re: Breaker Points

Got my fingers crossed for you. Let me know how it goes.