Case SC Valve issues

ptosean · Jan 12, 2022

So a couple years ago I was using my SC to rake some hay. During that the tractor developed quite a miss and I ended up parking it until that winter (2020-2021). When winter hit I took the head off and discovered a broken piston on the number 3 cylinder (which I had had a problem with in the past not running when not under load). So I replaced the piston and put rings on all 4. I took the head to an engine shop and they ground the valves and seats. This summer I reassembled the engine and after some issues with me figuring out how to get the mag in time it ran just like it did before I took it apart, not running on number 3. So a friend of mine looked at it and he discovered what he thought was a weak valve spring. If you pulled up on the spring with a screwdriver while running it would run nice and smooth on all 4, but if you took the screwdriver out it would go back to 3. So I ordered a new spring and installed it. Still doing the same thing. Any ideas? I'm getting between 95 and 100psi for compression on number 3 and 100 to 110 on the others. Any suggestions are welcome. Thanks.

rustred · Jan 12, 2022

did these guys bother to check the spring tension??? it is standard procedure on a valve job. might be a weak spring. plus do you have good spark on that cyl.?

J Hamilton · Jan 12, 2022

My first thought would be the valve and seat are worn out and the spring is at or near the max extended length and not allowing it to fully seat while running, or the valve has a slight bend and binding just a little in the guide. How much did you have to compress the spring when installing the keepers?

jal-SD · Jan 13, 2022

SC's are noted to have valve springs weaken & even break under extended usage. I'd check out what the specific tension the factory springs were supposed to be & find some new ones that have a slightly higher tension raiting. We've done that, but I don't remember what the tension ratings were. My '44 SC ran much better after the head was done that way.

ptosean · Jan 13, 2022

I believe I have good spark. I had the mag gone through as well. I'm not sure what all they checked. Honestly it wasn't a good experience. They took forever to do it and when they did get it done I think they just did a quick and dirty to get me off their back. I'm afraid it's a bad guide or seat, as the new spring isn't changing much, I just don't want to take the head to another shop but I might have to.

John Saeli · Jan 13, 2022

I've read & re-read your post. It has to be the spring, for 1 reason or another. I'd simply shim the spring & try it.

ptosean · Jan 13, 2022

Well it's definitely a farmer fix but it works for now. I took a flat washer and cut the hole out so it was the inside diameter of the spring and put it in there. Might be temporary but it works for now. She's hitting on all 4. Thanks for the input!

John Saeli · Jan 13, 2022

There you go!! Shimming springs is not uncommon, but they are always shimmed from the bottom. Put that shim on the bottom, maybe try a thinner shim, and you'll have a permanent professional fix. Good luck.

rustred · Jan 13, 2022

yes as john and i say ,... shims always go on the bottom. there was also different thicknesses. but if they checked the springs they would ahve found it weak and it should have been replaced. i still would replace tha spring. very easy to do. put some air to the cyl. and remove and replace that spring. if its that weak it will not perform at high rpm.

John Saeli · Jan 13, 2022

Right now, I doubt he could find an SC Spring. Been on back order for a long time. If that valve & seat are pounded and or ground in, a new spring won't help and would need shimming anyways.

rustred · Jan 13, 2022

he said he took the head to a machine shop and had the valves and seats done. so if that s the case they have no clue. springs get weak. i would like to know if they checked spring tension.

J Hamilton · Jan 13, 2022

Agkits shows online that they have them in stock, I don't know if they actually do or not

John Saeli · Jan 13, 2022

They don't.

J Hamilton · Jan 13, 2022

I'm glad I saved my old ones from having the head redone on mine last year, for a just in case situation

casecollectorsc · Jan 14, 2022

Had a broken spring on a DC that I replaced with one from a Chrysler 318 v8.

tomturkey · Jan 14, 2022

Bubble gum, duct tape, baling wire, an old washer, whatever it takes to keep the Case machine rolling. Valve stem grew taller when it was recessed into the head further from grinding, making the spring to short to pull it closed. Requiring a shim under the keeper. Something to remember when having a head worked on. gobble

mEl · Jan 14, 2022

John,that spring does no look like a match for the other ones, it has a lot more gap between coils than the others. lookin at the height of the ends of the rockers there does not seem to be a drastic height difference between that valve and it's neighbors. If a valve and seat were ground enough to loose all valve spring tension you should be able to see it there, I'm bettin that someone either substituted a spring off another head and did not get a spring the right length or the engine shop picked up a wrong spring after the valve work. Most Case springs are built with progressively closer gap in the coils toward the bottom of the springs, the spring in question is not built that way, look at the spring and then look at those in view, you will see what I mean.

J Hamilton · Jan 14, 2022

Good eye to notice that! Its obvious now you
pointed it out. The original poster had also
stated tgat he had ordered and replaced that
spring, so he may have been sent the wrong
one or it may be an aftermarket design.

ptosean · Jan 15, 2022

I think you are all correct. I think I had a combination of every possible issue mentioned here. It is a new spring and the coils are different, but I think it is just an aftermarket design. They were the exact same size and length, and they felt very similar. I wasn't very happy with the shop that did the valve work. They took forever to do it and that was after me nagging them for a couple months. I don't think he checked spring tension, the only thing he said when I picked it up was that that was probably the last time I'd get away with grinding, next time valves and seats would probably need to be replaced. And I'm guessing that it'll need guides too.

J Hamilton · Jan 15, 2022

I wouldn't be happy with their work either, but I also know a good machine shop is hard to find. Lucily I have a very good one close by. Sometimes it takes a while to get machine work done, but they do a lot of work and very honest. If they find something close to being out of spec they will ask if you want to proceed as is or replace the worn parts. I had them do the head on my SC last year with new valves, seats, guides and springs. I always save my old valves and springs for a just in case moment lol

Case SC Valve issues

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