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Author Topic: Ignition Points tip for Orwicks and others  (Read 523 times)

Offline Jim Kraft

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Ignition Points tip for Orwicks and others
« on: September 07, 2009, 07:49:33 PM »
After having trouble with points on several engines being loose in the moveable arm, I just make it a habit to solder the points to the moveable arm. I had a problem on my Orwick that I was having trouble finding. It was hard starting, and after I did get it running, it would run fine for a little bit, and then start missing, and some times just die. I put it on the test stand, and watched the points while it was running, and when it would start to miss, I noticed oil seeping around the fixed point. To make a long story short, I soldered the fixed point, and now she runs like a sewing machine. For those who don't know, Orwicks have a rather unusual timer, as the fixed point is attached to a brass band that goes around an insulated tapered band, that is used for adjusting the point gap. Since this type of timer is unique to Orwicks, it is probably the only engine I know of that can have this problem.
Jim Kraft

Offline FLOYD CARTER

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Re: Ignition Points tip for Orwicks and others
« Reply #1 on: September 08, 2009, 03:24:26 PM »
Hey Jim.  I've been running Orwicks since about 1948, or so (have owned 6 of them).  The timer seems to be the most reliable part of the engine.  The REAL SECRET is:

use a transistor amplifier!  This reduces the current through the points to a few milliamps, and the switching effect of the transistor compensates for dirt, oil, or oxides on the points.  In fact, you can have up to several Ohms closed resistance through the points, and still get reliable spark.

The Orwick moving point is of the "break" type.  That is, contact pressure comes from the spring steel that the moving point is made of.  (the cam serves to "open" the contact).  If this spring is worn or bent, contact pressure may be weak, causing high Ohmic resistance when closed. There are "ways" to increase contact pressure, but this involves bending the spring, or filing on the timer casting.  I would avoid this unless as a last resort.

Floyd
90 years, but still going (mostly)
AMA #796  SAM #188  LSF #020

Offline Jim Kraft

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Re: Ignition Points tip for Orwicks and others
« Reply #2 on: September 08, 2009, 05:43:04 PM »
I agree Floyd, that it is a very nice working timer. But even running the transistor ign. I have had trouble on Super Cykes, and Spitfires, with the points being loose enough in the moveable arm to cause problems. Same on the Orwick with the fixed point, as it is pened into the brass band. All of my enignes are run on transistor units. After soldering, it runs just fine. I know I am not the only one who has had trouble with points coming loose even with transistor ign. A couple of years ago, Dave Shirley Jr. had the same problem on his Super Cyke at VSC. He soldered the points, and all was well. I should probably just replace the points when they do this, but soldering seems to work. It is very hard to detect any looseness of the point, but after soldering they start and run. The point spring on the Orwick puts way more pressure on the points than any of my other engines. That could have been part of the problem.
Jim Kraft


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