Compression on 1950 8N

leroy1142 · Apr 9, 2016

Can anyone tell me what the compression should be on my 1950 8N tractor. I would like to know the hi end and the low end. I keep hearing that you should do a wet and dry test, what do they mean by wet and dry. The engine that I ran the compression check on is as follows. I have 120, 108, 108 and 83. Thank you for your time.

leroy1142

hadley · Apr 9, 2016

83 is pretty low

gene bender · Apr 9, 2016

I would check #3 see if valve is stuck or has clearence its like the valve just isnt closing tight.

old · Apr 9, 2016

On the N series 90 is about as low as one want to have an engine that runs well. As for wet and dry test it is this way. You check compression dry as in right after you have run it to warm it up then check then after the first check you add a table spoon or so of oil and then check again. That 83PSI says that cylinder has a problem like a valve that is not closing and or stuck or broken ring etc.

Dell (WA) · Apr 9, 2016

LeRoy.........Ford specs fer 8N is 90psi min; good runnin' 8N's are about 110psi; brand new rebuilt 8N's about 125psi; ........HTH, the amazed Dell

leroy1142 · Apr 9, 2016

OLD, I thank you for the information it is helpful, but I steel would like to know the compression ranges.

leroy1142

old · Apr 9, 2016

A good fresh rebuilt engine will have up wards of 125PSI maybe a tad more and a engine that is pretty close to worn out is 90PSI and under. That is on the N series flat heads

leroy1142 · Apr 9, 2016

Dell thank you for the information. This will help.

leroy1142

leroy1142 · Apr 9, 2016

Dell thank you for the information.

leroy1142

Bob · Apr 10, 2016

Leroy, do a "cylinder leakdown test" on it to determine (by where air escapes) what is causing the low # an the one cylinder.
Leaky, leaky here...

jimg.allentown · Apr 11, 2016

I don't know the actual specifications for that specific engine, BUT.....
The spread between the highest and the lowest cylinder should be no more than 10%.
The spread from 120 to 83 is too much. It indicates a problem with a weak cylinder. Could be rings, valves, or head gasket. The wet/dry compression test would help to pinpoint whether it is rings or valves. A leakdown test will tell if it is a head gasket, rings, or valves.

Compression on 1950 8N

leroy1142

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hadley

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gene bender

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old

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Dell (WA)

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leroy1142

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old

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leroy1142

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Bob

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