Hello, I am repairing an nice 59 Evinrude 3hp. My dad had it and had complained of low power-not revving up fully. He bought it from a roadside sale. I know it was just a poorly tuned carb, but it had too many tell tale signs of it being tinkered with. I decided to pull it down to just the short block for now as $150.00 for gaskets and rings is cheap insurance.
A few questions.
1) What is a good compression number? I got 60 psi on each, forgot to oil the cylinder to do a wet test, but there is a good oil film in each bore. I know the gauge is good because I get 120 psi out of my 9.9 hp.
2) Does everyone still run the 24:1 mix with this engine? My friend has a 68 Johnson 3 hp and by all looks of it it is the same basic engine and it calls for 50:1. Tuned right it shouldn't smoke much, but just curious.
3) Lastly, I want to double check the orientation of the pistons, as this engine has been opened up in the past. They look correct from memory and double checking off my 6 hp & 9.9 Johnson's. Squared side of the dome towards the exhaust, and the smoother taper towards the intake transfer ports correct? Only reason I ask is because my 1960's Neptune 500 has the piston the opposite. Squared side of the dome towards the intake transfer ports. Guessing this was a mistake on Neptune's part? I installed that piston per the owners guide that came with it.
Thanks again for the help.
Brian
P.S. Also, I noticed that the intake port is really tiny compared to the carb bore. Guessing this was done to make it a "3 hp"? Has anyone port matched this before? I will leave this alone as it is my Dad's and is really nice engine. But if was mine I would port match, and watch to avoid over revving it.
A few questions.
1) What is a good compression number? I got 60 psi on each, forgot to oil the cylinder to do a wet test, but there is a good oil film in each bore. I know the gauge is good because I get 120 psi out of my 9.9 hp.
2) Does everyone still run the 24:1 mix with this engine? My friend has a 68 Johnson 3 hp and by all looks of it it is the same basic engine and it calls for 50:1. Tuned right it shouldn't smoke much, but just curious.
3) Lastly, I want to double check the orientation of the pistons, as this engine has been opened up in the past. They look correct from memory and double checking off my 6 hp & 9.9 Johnson's. Squared side of the dome towards the exhaust, and the smoother taper towards the intake transfer ports correct? Only reason I ask is because my 1960's Neptune 500 has the piston the opposite. Squared side of the dome towards the intake transfer ports. Guessing this was a mistake on Neptune's part? I installed that piston per the owners guide that came with it.
Thanks again for the help.
Brian
P.S. Also, I noticed that the intake port is really tiny compared to the carb bore. Guessing this was done to make it a "3 hp"? Has anyone port matched this before? I will leave this alone as it is my Dad's and is really nice engine. But if was mine I would port match, and watch to avoid over revving it.
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