Piston Rings/ Bore

[CraigKennedy]

Hey yall, I've been rather busy lately and I've been trying to find more time from my engine rebuild. I've measured the bores, everything is within the taper limitations, but on my #1 cylinder the the out of round, Side to Side, top measurement is 0.00285 and the not exceed limit is 0.0026. Should I worry about this? and yes I have remeasured a few times and this is what I keep getting.
And another question, I've got my bore measurements from side to side, front to back, I know its a stupid question but how go i figure out what size over rings I need?
Thanks yall
Craig

[coralhead]

I'm not sure what you tools are using to measure within .00025 on the bores but I would say being .0002 out of tolerance is not going to hurt you.

[DieselDennis]

You say the top measurement is 0.00285. I guess that's the side to side measurement. What was the measurement front to back? Give us some more measurements from bore #1.

[CraigKennedy]

Measurements of #1 cylinder, A being front to rear, B being side to side.
A

[CraigKennedy]

#1 cylinder measurements, A front front to rear, B from side to side
A B
Top, below ridge: 2.6326 2.62975
1/4 down : 2.6274 2.62665
1/2 : 2.6269 2.6264
bottom: 2.6244 2.6251

[DieselDennis]

Do you want to double check your numbers for that Top, below ridge line? Those numbers you posted tell me that you're 0.0649" out of round at the top. Which is too much.

The first post you said you were 0.00285" out of round.

[CraigKennedy]

Dennis, I fixed it, I was meaning 2.62975, lol, I wasn't looking out my good eye

[DieselDennis]

If you have a place on a cylinder that's reading 2.6326, then that's ( 2.6326-2.625= ) 0.0076" past the nominal bore size. Then next size up would be a 0.010" oversize.

So then you'll have to get your bore up to 2.635" diameter. And preferably you do the entire engine 0.010" oversize.

Of course, this will mean some machine work for your engine. The good news is, the oversizing will take care of your out of round condition.

[ricky racer]

Unfortunately your bores are worn out. Time to make a decision. Do you rebuild it and have a like new engine or do you buy another running Cub for about the same money and hope the motor is better than the one you've got. Now the plus as I see it, is your engine is still on it's standard bore so it apparently hasn't been used to death like a lot of them out there. My '53 was not quite a worn as yours. My most worn cylinder was about .005" over nominal measured with a bore gauge. As I disassembled the engine I couldn't believe how little wear everything had. Anyway, long story short I bored the engine and rebuilt it completely as well as rest of the tractor. I've never regretted the investment and the Cub has never let me down or given me a minute of trouble since. That's been about 8 years now and it gets lots of use. I understand the cost of a rebuild may not fit every budget. However, putting half that amount into a re-ring job, bearings and seals, etc. when the cylinders are worn out just doesn't make since to me but it's not my decision. Everyone has to make there own decisions and establish their own priorities and I'm sure you'll make the decision that is right for you.

[CraigKennedy]

Thanks yall, I'm still between calling the shot on this engine, I'm not going to use this tractor for work but just for show. Last year when I did a compression test, The ranged from 105 psi on #1 to 95 on #4. I think rebuild compression is 120 psi??

[CraigKennedy]

yall, If I do have the block rebored to 2.635" will that call for new pistons?

[Eugene]

yall, If I do have the block rebored to 2.635" will that call for new pistons?

Yes.

[CraigKennedy]

Well, I'm going to try to talk to the machine shop sometime this week, and see what they will charge to rebore. Does anybody have recommendations on rebuild kits? a specific brand or website? Not really looking dome tops.

Thanks Craig

[Eugene]

Typically the least expensive way to purchase pistons and rings, the rebuild kit, is through the machine shop.