Topic: 1977 Johnson 2 hp Piston ring gap – Antique Outboard Motor Club,Inc

This topic has 8 replies, 5 voices, and was last updated 7 years, 10 months ago by fleetwin.

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February 21, 2018 at 7:01 am #9270
PugetSoundBoater
Participant
I have temporarily misplaced my ’77 2 hp manual. Anyone know the ring end gap for .030 oversize rings?

I want to thank Dan A. in Tennessee for arranging the boring of the block to .030 over by his friend Jason White at:
Jay’s Block Shop in Sparta,TN He did a great job!
Thanks to Dan and Jason!
Jim PSB

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson
February 21, 2018 at 3:39 pm #71422
Tubs
Participant
Hastings recommends a MINIMUM of .0035
gap per inch of cylinder diameter.

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.
February 21, 2018 at 4:34 pm #71424
fleetwin
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US Member
Jim
Sorry, don’t have a 1977 manual. But, the 1979 manual prescribes the ring end gap to be: .015" min-.025" max
The 1972 manual prescribes: .005" min-.015" max.
So, I guess we better find the correct 1977 manual to be sure.
I am assuming you are using OMC piston and rings. If not, I would look for the end gap recommendation from the manufacturer of the parts you are using….
February 22, 2018 at 12:05 am #71435
PugetSoundBoater
Participant
Fleetwin-I am using OMC .030 piston and rings. Guess i’ll have to start digging through a large stack of assortment of boxes till i find the manual. Thought one of us would have the info more handy. Hope the info is in the manual covering .030 ring gap.Thanks, Jim PSB

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson
February 22, 2018 at 10:17 pm #71450
Mumbles
Participant
I found the specs for your motor and for the ring gap it says 0.025 max and 0.015 minimum. New rings these days don’t usually need filing to fit and their gap should be towards the lower spec right out of the package.
February 23, 2018 at 6:39 am #71458
PugetSoundBoater
Participant
Thanks for all of your responses.
Jim PSB

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson
February 23, 2018 at 1:39 pm #71463
jerry-ahrens
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US Member
I have a 1974 manual that say’s .005 -.015 is acceptable. If that helps any…
February 23, 2018 at 4:15 pm #71470
Mumbles
Participant
Jerry’s numbers seem more reasonable. I double checked my source and that’s what it said, 15 to 25 but doesn’t seem right. It could have been a typo. If you have a dealer nearby, they should be able to confirm the proper gap size for you.
February 23, 2018 at 9:29 pm #71484
fleetwin
Participant
US Member
The ring end gap spec changed over the years, have found the tight gap spec in the early 70s manuals, the relaxed spec in the 79 manual…
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