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8n oil pressure

Kevin s I am curious, what should the average oil pressure be on an 8n at full throttle?
Bob G It will vary a lot. the relief valve will open around 45 lbs moe or less.It will be more on a cold engine than a hot one. mine runs at about 20 to 25 lbs when mowing at 540 PTO RPM/3/4 throttle. I consider that pretty good. Wide open will run 40 +
Dave Mine goes to almost 60psi on start up and steadies up at 25-30 once it's warm at about half throttle. Idles at about 20psi warm. I've always heard a rule of thumb for acceptable oil pressure is 10psi per 1000 rpm. If that is true then a little less than 10psi at idle up to about 25-30 at high rpm should be fine. The manual I have doesn't have OP specs in it. Dave
Kevin s Thanks guys
I don't have a tach. so just checking to see how mine compared. I believe I'm pretty close to normal then.

Ken Pike According to the 8N owner's manual oil pressure at 3/4 throttle should be about 27 PSI. With all new bearings, good camshaft bearings & a good oil pump you can probably get more pressure by monkeying with the spring in the pressure relief valve. My late '47 8N runs a bit over 20 lbs. cold or hot & shows 10 lbs. or slightly less at hot idle. Supposedly rebuilt about 12 years ago.


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