smoking from rebuilt

[garlicman]

my 56 cub stills smokes a little after 20 hrs on the rebuilt engine. Is this normal ?

[Slim140]

Did you bore it or just put rings in it?

[garlicman]

I was told it only had new rings

[Slim140]

Probably needed boring if it's still smoking after 20 hours. I rebuilt one recently and it had been bored .030" over previously and it all measured in tolerance so I only put rings in it and it hasn't smoked at all.

[garlicman]

what is the down side if I don't have it bored. I was told it did not have to be bored.

[Slim140]

It will smoke, under powered, spark plugs will foul etc. Do you have any way to do a compression test on it? That will tell you a lot.

[garlicman]

no I don't but have friend that might what should it be at

[Slim140]

120-130 is normal, should be after a rebuild anyway.

[garlicman]

ok thanks I was told it was not seated yet

[Eugene]

I was told it only had new rings

I understand this sentence to mean that you are not the one who put this engine together. Correct?

20 hours on the engine, engine should be broke in. Did you cross hatch hone the cylinders?

[Stanton]

no I don't but have friend that might what should it be at

Handy to have around...


https://www.napaonline.com/napa/en/p/BK_7768080/BK_7768080

[Urbish]

Handy to have around...


https://www.napaonline.com/napa/en/p/BK_7768080/BK_7768080

I have the cheapie from Harbor Freight. Works fine:
http://www.harborfreight.com/compression-test-kit-8-pc-62638.html

[Matt Kirsch]

Yeah, if it hasn't seated by now, it isn't going to.

I have heard legends of putting some sort of dry abrasive cleanser (Bon-Ami?) in the intake as a old-timer's trick for seating rings. Not sure I would have the guts to try it.

Who told you the cylinders didn't need to be bored? If it was an engine machine shop, that's one thing, but I would still have my doubts because it's rare to impossible for a cylinder to wear perfectly round. They are usually somewhat egg-shaped.

[garlicman]

ok just tested and low all within 10 % (65, 66, 70 ,68)

[Slim140]

There's where your smoke is coming from, needs a bore. Crank it and take the oil fill tube out and see if it's blowing out there while running. That will indicate needs boring too if it has new rings in it.