piston ring gap

[mrcrw009]

I have a 35 hp 1976 evinrude and i just deglazed the cylinders today and i was wondering what the ring gap should be? I have new rings, they are the standard size and it took quite a bit of deglazing so i was wondering if i took to much off and if so would i just get oversized rings and file them down the the right dimension if the standard ones will not cut it? Also the sides of the pistons are kinda beat up what is the best way of smoothing them out or just cleaning them up a little? any help would be great thanks.

 

[milliesdad]

Re: piston ring gap

Go with new pistons if the skirts are scuffed on the ones that were removed.

No sense going cheap and have to do it all over again

 

[mrcrw009]

Re: piston ring gap

ya i was thinking about that will the scored pistons score up the cylinder walls i guess

 

[HighTrim]

Re: piston ring gap

It depends on the pistons. Best thing to do is post pics so we can see them. If you run your finger over the pistons will it grab the scuff? If it only light wear, you may be ok. But cant tell until we see them. \

Did you hone them yourself or pay a shop? What method was used? Have the bores been checked for round?

 

[mrcrw009]

Re: piston ring gap

ya they are scored pretty good you can catch a nail on them for sure. I will post some pics of them. Ya i honed them myself i cant think of the proper term for the tool but its a deglazer that uses the spring loaded square stones. no i have not checked it for out of round but i could take a mic to it tomorrow at work and see is there a tolerance or should it be perfect.

 

[mrcrw009]

Re: piston ring gap

another thing does anyone know the original diameter for the cylinders?

 

[boobie]

Re: piston ring gap

You may want to get an OEM factory service manual as all the specs are in them and it will help you out if you have other probs with the mtr.IE ign,g/c, carbs and ect.

 

[sschefer]

Re: piston ring gap

Ring end gap can usually go to a max of .025 maybe even more. The minimum for that motor would be around .017 without risking end bump. You'd be suprised at what you can get away with on these motors.

Using and 3 stone hone is the thing that concerns me. They are o.k. for a quick clean up but if you had to work at it at all you probably egg shaped the cylinders. Depending on what you're expecting out of the motor this may or may not make a difference. If you want it to run like new, it's not going to but it will probably run decent enough to get you to a fishing hole for the early bite.

Getting it back to factory new performance will mean either buying a bore gauge or taking it to a shop and having it checked. You can make a decision then whether to bore it or look for another one. Whatever you do, don't buy another part until you have the bore checked if the performance is going to be an issue.

 

[mrcrw009]

Re: piston ring gap

ok ya i pretty much just want it to run so i can go fishing. the compression was like 40 on both cylinders and it was just fouling the plugs. doesn't have to be perfect just want it to run decent. i spent about 5 to 7 min on each cylinder with a fine grit stone.