Piston ring end gap 63 Farmall cub

[Paul 300 U]

Hello. Continuing the valve and piston replacement on my cub. I reamed the ridge one more time per my previous post and very little material came off. I honed each cylinder once more about an additional 5 to 10 seconds. There is still a bit of a ridge but I decided to leave well enough alone.

My aluminium pop up pistons and rings are in. Today I measured the end gap and I'm pretty snug at .026. I believe my target is between .007 and .017. As usual, what I read varies tremendously on how serious of an issue this may be.

I'll look forward to your feedback and solutions. I am not aiming for this tractor to be perfect. Just a decent running machine. Thanks! Paul

 

[Duner Wi]

What is end gap 1/2 inch down and also very near the bottom of cylinder? You have more end gap than I would want in my engine with that diameter cylinder.

 

[Paul 300 U]

What is end gap 1/2 inch down and also very near the bottom of cylinder? You have more end gap than I would want in my engine with that diameter cylinder.

Duner Wi. Thanks for the reply. The gap at .5 inch is .026. The gap near the bottom (about 4.5 inches down) is. 010. Thanks Paul

 

[RedMVa]

Duner Wi. Thanks for the reply. The gap at .5 inch is .026. The gap near the bottom (about 4.5 inches down) is. 010. Thanks Paul

Yeah more than it should be but I’ve seen quite a few with more. Result is some compression loss and probably burn some oil. Next question is what is the piston clearance?

 

[Duner Wi]

Duner Wi. Thanks for the reply. The gap at .5 inch is .026. The gap near the bottom (about 4.5 inches down) is. 010. Thanks Paul

If it was mine and I spent money on new pistons and rings I definitely would bore it. I would expect increased blow by with that amount of taper.

 

[rustred]

Hello. Continuing the valve and piston replacement on my cub. I reamed the ridge one more time per my previous post and very little material came off. I honed each cylinder once more about an additional 5 to 10 seconds. There is still a bit of a ridge but I decided to leave well enough alone.

My aluminium pop up pistons and rings are in. Today I measured the end gap and I'm pretty snug at .026. I believe my target is between .007 and .017. As usual, what I read varies tremendously on how serious of an issue this may be.

I'll look forward to your feedback and solutions. I am not aiming for this tractor to be perfect. Just a decent running machine. Thanks! Paul

the spec is .004 for every inch of cylinder bore. you are way over with the cylinder wear, like about double. measure the gap near the bottom of the cylinder where there is no wear and compare the difference.

 

[Duner Wi]

The gap at .5 inch is .026. The gap near the bottom (about 4.5 inches down) is. 010. Thanks Paul

 

[rustred]

and you want to know the wear on the rings, check the gap with a used ring in the same spot you will see a lot bigger gap. DONT keep honing the cylinders.. you are removing material. you will never hone out a ridge. you have tapered cylinders with all the wear. cylinders ALWAYS wear more at the top, and less as you go down. if a person install new pistons then it should have the sleeves replaced also. to let the rings do their job in the piston and not keep the rings working on a tapered cylinder, that .010 at the bottom is what the top should be also.

 

[Janicholson]

and you want to know the wear on the rings, check the gap with a used ring in the same spot you will see a lot bigger gap. DONT keep honing the cylinders.. you are removing material. you will never hone out a ridge. you have tapered cylinders with all the wear. cylinders ALWAYS wear more at the top, and less as you go down. if a person install new pistons then it should have the sleeves replaced also. to let the rings do their job in the piston and not keep the rings working on a tapered cylinder, that .010 at the bottom is what the top should be also.

With respect, it is a Cub with no sleeves. So this is the way it will be for this engine as there is no boring and oversize pistons going in. Jim

 

[rustred]

It still can be bored and sleeves made. But way too much money for a tonka toy.

 

[Duner Wi]

Pistons are listed in std, 020, 030, 040, and 060. Sleeves are in Melling catalog in 2 5/8 with 1/8 Inch wall thickness. 3/32 wall thickness if you want .

 

[timcasbolt]

I'll bet if you can get a halfway decent cross hatch in those bores it'll work out just fine. Good old fashioned iron rings will seal up pretty fast on their own. You probably can't get a good enough finish for chrome or moly.

 

[used red MN]

Not going to say it won’t work, but here is another reason why myself and several others suggested the engine should have been bored. Every time the piston goes up or down in the bore the rings will be sliding ever so slightly in and out in the piston ring grooves due to the changes in bore diameter along the stroke of the piston. This will accelerate the wear of the ring grooves. Not sure if you are familiar with raising cattle on a farm but some may say “you have closed the gate after the cows are already out”. I know it is easy for me to spend your money and delegate additional time to you project from this end of the internet. In the hot rod world it would be called “bench racing” not sure what it’s called when applied to tractors. Put it together, if it is not going to be used real hard it will probably be fine for a long time.

 

[Butch(OH)]

With that kind of taper in the bores your rebuild isn't going to last as long as a prim and proper one. However if your usage will be low hours then go ahead with it. If your expectations are new engine life and performance then it either needs to be bored for oversize pistons or dry sleeved back to std bore size.

 

[Butch(OH)]

Not going to say it won’t work, but here is another reason why myself and several others suggested the engine should have been bored. Every time the piston goes up or down in the bore the rings will be sliding ever so slightly in and out in the piston ring grooves due to the changes in bore diameter along the stroke of the piston. This will accelerate the wear of the ring grooves. Not sure if you are familiar with raising cattle on a farm but some may say “you have closed the gate after the cows are already out”. I know it is easy for me to spend your money and delegate additional time to you project from this end of the internet. In the hot rod world it would be called “bench racing” not sure what it’s called when applied to tractors. Put it together, if it is not going to be used real hard it will probably be fine for a long time.

Agreed, we have the online race engine dreamers and the slop it together crowd. Reality for most old tractor engines is somewhere in-between those extremes depending on the expected service.

 

[Paul 300 U]

Pistons are listed in std, 020, 030, 040, and 060. Sleeves are in Melling catalog in 2 5/8 with 1/8 Inch wall thickness. 3/32 wall thickness if you want .

Probably and oversimplified question but can I do sleeves myself?
Thanks Paul

 

[rustred]

Probably and oversimplified question but can I do sleeves myself?
Thanks Paul

No. It’s machine shop work. And expensive. The block has to be bored. A sleeve has the be made if none available. And they need to be interference fitted and pressed in. Then the sleeves honed for the piston fit. Block has to be removed from tractor.

 

[Paul 300 U]

Hello. Continuing the valve and piston replacement on my cub. I reamed the ridge one more time per my previous post and very little material came off. I honed each cylinder once more about an additional 5 to 10 seconds. There is still a bit of a ridge but I decided to leave well enough alone.

My aluminium pop up pistons and rings are in. Today I measured the end gap and I'm pretty snug at .026. I believe my target is between .007 and .017. As usual, what I read varies tremendously on how serious of an issue this may be.

I'll look forward to your feedback and solutions. I am not aiming for this tractor to be perfect. Just a decent running machine. Thanks! Paul

I'm going to reply to most everyone here since I tend to make a real mess of the string when I do multiple, individual replies.
First thank you for the replies. I've had good success in the past weighing the replies and moving forward with a process. I understand that some are recommending the ideal and I'd like to proceed that way but then reality (budget, time, etc.) sets in.
I paid a very reasonable price for this tractor and my goal has been to get it to run as best as possible within a reasonable budget.
I would like to know more about sleeves per Duner Wi comment. Is that something that will work without reboring? Can I press them in myself?, approximate cost? Barring that suggestion or anything new I will probably proceed to install my new pistons and rings. If there is anything else I should be doing while I complete, please let me know and thanks again! Paul

 

[Paul 300 U]

I should mention that my "reasonable" budget I mentioned above includes: complete new valve assembly, gasket kit, pop up pistons w/rings and of course maintenance items like new plugs, filter etc. Thanks

 

[Duner Wi]

I should mention that my "reasonable" budget I mentioned above includes: complete new valve assembly, gasket kit, pop up pistons w/rings and of course maintenance items like new plugs, filter etc. Thanks

Here is what I consider normal best practice for your situation.
Bore it to first oversize that cleans up your bore and install new pistons. When you reach limit on boring say .060 that is largest oversize I see then you would sleeve engine back to standard. If you engine had factory installed sleeves than you would get sleeve and piston sets unless one piston got damaged somehow. Boring costs vary by local . Check locally.