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A good read.

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John, it all has to do with time and splitting it up with the other hobbies and family. You know the story. Plus, I like the passion from our friends across the pond and I thought that some of my stuff should be in the archives.

Edited by Webhead

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Thanks for reposting the NIAE test report, they certainly had a lot of problems the the early engines they tested.

I found a test report made by the U.S. Department of Agriculture in May 1964 for the Paradox pump online recently, I posted it in the Electro Flow pump thread, but here is the link again; http://www.fs.fed.us/t-d/pubs/pdfimage/64511303.pdf

I've downloaded a copy in case it disappears the the linked site.


Even though I only took three O&R tools to this years "1000 engine rally" over here, they certainly attracted plenty of interest and there was even a few people that remembered using them in the past.



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I noticed a while ago that the scanned pictures of the NIAE test report in the first post had reduced in size and as I now have an original copy of the test report, I have created a pdf from it;

NIAE Test Report Ohlsson & Rice Model J Engine Published Feb 1964.pdf


The NIAE tested a couple of O&R's between Jan-May 1963 & published a report in Feb 1964.

They originally intended to run the engine for 100 hours to determine the suitably for agricultural use & the maintenance requirements, they concluded that the early engines tested were only suitable for intermittent use.

The first serial number tested was 030957 (model J), it had problems with the die-cast gears being very badly worn, they got through two sets of gears during a 31 hour test & the first set of gears jammed up due to a broken tooth, the cork clutch lining material was also worn.

They did tests on a couple more engines (model letters not stated);

  • s/n 030987 with gearbox, this also failed with a broken gear tooth after 20 hours.
  • s/n 030987 with direct drive taken from s/n 030993, test abandoned as the PTO shaft wouldn't stay tight on the taper.
  • s/n 053595 with drive through clutch, this was the longest test (50 hours), it mostly only had minor problems.

O&R stated that the NIAE test was inappropriate for this engine, which would have been more realistically tested in complete equipment with normal operation times & intervals. They also made some design changes between Oct & Dec 1963, these included;

  • an improved clutch & steel gears (were die-cast).
  • more needle roller bearings with steel cages (were plastic).
  • bigger exhaust ports.
  • plastic reed valve (was metal).
  • primer button on carb (a kit was available to update earlier engines).
  • governor vane modification.
  • fuel/oil mix changed to 24:1 (32:1 now recommended with modern oils).
  • quadrant speed control on carb.

The U.S. Department of Agriculture tested the direct drive Paradox pump in May 1964 and managed a 99 hour test with only a failed coil & a new set of piston rings being required. General maintenance included a couple of replacement spark-plugs and de-carbonising of the exhaust ports after 25 to 35 hours of continuous operation. See the previous post for a link to this report.



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