'42 A piston ring questions

[620 John]

So.....

Working on a '42 A that was stuck. Long story short I got it freed up, pistons and block removed. Got a different block with std bore because original was going to need to be bored out. I'm using the original all fuel std pistons that were in it. Got a new set of piston rings for it and noticed the new ring set came with 3 compression rings and 2 oil rings. The bottom oil ring is a 3 piece design and the upper is the normal style ring with holes in it.

To me having that 3 piece design oil ring at the very bottom groove is asking for trouble because it might catch the bottom lip of the bore. I'm thinking maybe leaving out the 3 piece ring and using one of my old rings in the 4th groove. Then install the one piece oil ring in the bottom groove like it was originally. What do you guys think????

Did find a couple of older threads on this topic but nobody really posted back what they did

https://forums.yesterdaystractors.com/threads/john-deere-a-oil-ring-question.541729/

https://forums.yesterdaystractors.com/threads/5-ring-jd-a-piston-question.539433/

Second question. I know this "new" block has some wear in it and there's a slight ridge at the top of the bore. I'm thinking about adding another gasket to the block so the top ring doesn't hit the ridge. Bad idea??? Or should I lightly grind the edge of the top ring down a little??

When I did my B I was able to use a ridge reamer to remove the ridge but most reamers only go to 5" . The A has 5.5" bore and haven't found a reamer that goes that big.

Thanks in advance

 

[M-MAN]

Adding another head gasket isn't going to effect the piston stroke. Only the crankshaft can do that.

 

[Watthour]

https://forums.yesterdaystractors.com/threads/large-bore-ridge-reamer.930659/

 

[used red MN]

Adding another head gasket isn't going to effect the piston stroke. Only the crankshaft can do that.

I suspect he means adding a second gasket under the cylinder block section.
To the OP or others a question and I am not a Deere guy. He has a concern about the thin 3 piece ring catching on the bottom of the bore. Since he said this I looked at some blocks for sale in adds, I was expecting to see a convex or half moon cut on the bottom meaning that only part of the ring might pass out of the bottom of the cylinder which probably works. But the blocks look basically square on the cylindrical end that faces the crank. In that case the ring cannot come out of the bore or it will expand and not go back in. So essentially is his concern valid?

 

[620 John]

Yes I was thinking adding a another gasket at the block to main case gasket joint.

My only concern adding another gasket is the bottom ring catching the lip of the bore. Gasket is about.030 thick. If I use the single piece oil control ring in the bottom groove of the piston I wouldn't think that little bit would cause an issue. I don't remember exactly how far it travels down in the cylinder. I think they use the entire surface of the bore.

I've heard of it happening with like a 620 or 630 when the oil ring groove would get too sloppy and allow the ring to come back too far and catch the lip of the bore. But those have aluminum pistons which would probably explain why they can get too sloppy.

 

[teddy52food]

Put a solid ring not the 3 pieced one in that bottom groove. the 3 piece will come out of the bore enough to let the 1 rail expand & come out of the groove when the piston goes back up. I have seen it on a B when somebody put it together wrong.

 

[620 John]

Put a solid ring not the 3 pieced one in that bottom groove. the 3 piece will come out of the bore enough to let the 1 rail expand & come out of the groove when the piston goes back up. I have seen it on a B when somebody put it together wrong.

That's exactly what I was thinking. That's why I'm leaning towards using one of my old compression rings in the 4th groove and installing the one piece oil ring in the 5th groove and leaving out that flimsy 3 piece ring all together.

Interestingly I was reading the description of the piston ring set sold here on YT and it says to put the 3 piece ring in the 4th groove and the 1 piece ring in the 5th. The description from the package I got my rings in (came from Steiner) says to install the 3 piece oil ring in the 4th groove and the 1 piece in the 3rd groove. But it doesn't take into consideration there's 2 rings in the package where it says to install them in the 2nd groove. Kinda contradicts itself. Not sure why these ring sets are coming with two different oil rings.

 

[rwhb12]

I have recently been working on a broken pipe in my 1946 gas kerosene A crankcase and the bottom piston ring groove on both cylinders is empty.

Russ

 

[MSD]

2 things you could do. Skip the bottom ring altogether. Will workout fine without it. Or you could put the piston in a lathe and cut a new groove in it up further. If you skip the ring drill some small holes in the bottom of the ring groove on the top side pf the pistons so the oil can drain back out of the groove.

 

[Mark-Ia]

www.handjmachining will have your tractor rings.

 

[620 John]

2 things you could do. Skip the bottom ring altogether. Will workout fine without it. Or you could put the piston in a lathe and cut a new groove in it up further. If you skip the ring drill some small holes in the bottom of the ring groove on the top side pf the pistons so the oil can drain back out of the groove.

I should probably clarify that this tractor isn't going to be doing a lot of serious work or pulling. It's going back together as a stock tractor. The guy who owns it just wants to get it running because it was his grandpa's tractor. He might use it for raking hay, pulling a small manure spreader, or parades ect.


As an update to the whole situation, I tried my hand at grinding the ridge out of the cylinder block with a die grinder and carbide bit. Seem to work pretty good. I was a little reluctant to try it but I found a little bit of a technique to doing it. So I put the block in with just one gasket.

Now I just gotta decide what I'm going to do with the rings. Definitely not putting that flimsy 3 piece ring in the bottom groove.