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Author Topic: Need some Orwick Advice  (Read 1010 times)

Offline Robert Zambelli

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Need some Orwick Advice
« on: October 25, 2012, 06:59:12 AM »
I was given a brand new Orwick 29 from, I believe, the early 50s. It IS NOT a replica.
I plan to break it in and put it on an OTS plane, possibly a Coasby Pagan.

Since the Orwicks evolved to Johnsons, I assume the metallurgy is similar - cast iron piston, steel sleeve.
I plan to run it in on 10-23, 50/50 fuel, as I do all my engines.

Any comments?

I will also post this in the OTS section.

Bob Z.
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Offline Jim Kraft

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Re: Need some Orwick Advice
« Reply #1 on: October 25, 2012, 08:04:28 AM »
The Orwicks had 3% nickel in the cast iron pistons, and seem to wear very well. After running my 64 for a while it has a bright shiny band at the top of the piston. It will probably run ok on your fuel, but if it was me I would run at least 25% oil. Your engine looks like the ign. model except for no timer. It is machined on the front and has what appears to be the cam on the prop driver. Henry may have kept those details on the "glo" versions. Don Hutchinson has been running a 29 ign. for some time, and his runs very well. Orwicks are very unique engines. If you take the back plate off you will notice the rod is polished to a mirror finish. If you look further into the piston, you will see that the wrist pin bosses have been brazed in to keep the piston light.

As an option, you could purchase a timer from Woody Bartelt or RJL, and run it on ignition.
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Jim Kraft

Offline Robert Zambelli

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Re: Need some Orwick Advice
« Reply #2 on: October 25, 2012, 11:02:21 AM »
Thanks Jim, but I have a new spark ignition version also.

Bob Z.
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Offline Steve Helmick

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Re: Need some Orwick Advice
« Reply #3 on: October 25, 2012, 05:01:13 PM »
I was under the impression that Johnson's had sintered iron pistons? Different than cast iron, and probably not as good. My .36bb had the skirt fall off the piston. Early Cox Conquests also had sintered iron pistons, and they were famous for pistons falling apart at high rpm. Whether Orwick used sintered iron or cast iron, I have no idea. Technically, Fox .35 Stunts use cast iron pistons, aka Meehanite, but fully machined from barstock.  D>K Steve
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Offline Jim Kraft

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Re: Need some Orwick Advice
« Reply #4 on: October 25, 2012, 05:50:17 PM »
McCoy Red Heads used sintered iron pistons also. According to Bill Tift who was a friend of Henry Orwick, the Orwick pistons were cast iron with 3% nickel. He also taper honed the steel cylinders so that they had a slight pinch at the top of the stroke. That, and the nickel in the cast made for the shiny band on the top of the piston. The early Orwicks had cast iron main bearings which some had wear problems. The later ones had aluminum alloy bearings that stood up very well.
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Offline FLOYD CARTER

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Re: Need some Orwick Advice
« Reply #5 on: October 25, 2012, 06:14:00 PM »
You can always identify an original Orwick manufacture by the piston.  Henry brazed the bosses for the piston pin.  Nobody else did that.  Although it was tricky and time-consuming, his pistons were lighter.

Floyd
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Offline FLOYD CARTER

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Re: Need some Orwick Advice
« Reply #6 on: October 27, 2012, 10:12:28 AM »
Another little fact about the Orwick 29 glo.  Henry Orwick designed the 29 and 32 for spark ignition, but they didn't sell very well.  He was persuaded to convert them to glo.  Subsequent production used the very same prop driver/cam as on the spark version.  The only difference: the steel cam was not "ground", but was left completely round. On later production of the 29, the prop driver was aluminum.

I lived just a couple miles from the Orwick shop in Los Angeles.  I had occasion to visit his shop several times,
.

Floyd
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Offline Robert Zambelli

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Re: Need some Orwick Advice
« Reply #7 on: October 28, 2012, 08:59:20 AM »
Thanks to all!!! You fellows are a wealth of good information.
In the early/mid 60s, I ran a lot of Johnson and Fox engines in combat, mostly on Voodoos.
I used the large case plain bearing Johnson Combat Special as well as the black head Fox Combat Special.
For the most part, we used Fox Hi-Nitro or Francisco Labs speed fuel (good nitrobenzine smell!!)
We wore out quite a few of the Johnson pistons/cylinders but never had a Fox wear out.
I still have my original Fox CS (still has great compression) as well as the Johnson but the Johnson has had the pistons/cylinders replaced a number of times.

It will be interesting to see how the Orwick 29 performs.

Again, THANKS!

Bob Z.
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