Valve replacement

[steveh1155]

I'm replacing the valves and associated parts on my 8N and I have to say, the old parts don't come right out like they do in the videos! It took me almost a full day to get the old valves and guides removed. The guides wouldn't budge when I pushed on the top with a ground down screwdriver. The only thing that worked for me was to pry the valve up off the tappet and tap on the old valve head to at least get the keepers to drop out. Then I could just lift the old valve out and get the spring off. Even then the guides had to be driven out with a hammer. I bought a 1 inch flexible hone to dress the guide bores, so hopefully I won't have any problems installing the new guides. Exhaust valves were somewhat easier than the intake for some reason. I bought a Neway valve seat cutting tool (used ebay), and I thought it took a 45 degree cutter for these seats, but when I looked at the cutter after it arrived it's in fact a 46 degree cutter on one side and 31 degrees on the flip side. Anybody know why there's 1 degree difference? Is this an appropriate seat cutter for 8N valve seats?
Thanks!

 

[HarryVanderpool]

It takes 3 angles. Call Neway and get the other angle.
They will want to know your arbor size.
Stop by NAPA and get some Prussian Blue as well.
If you do a perfect job, you'll be shocked at how your *N runs and performs.

 

[HarryVanderpool]

Reat this CAREFULLY, a few times:

Valve Seat Cutters - NEWAY

 

[used red MN]

I'm replacing the valves and associated parts on my 8N and I have to say, the old parts don't come right out like they do in the videos! It took me almost a full day to get the old valves and guides removed. The guides wouldn't budge when I pushed on the top with a ground down screwdriver. The only thing that worked for me was to pry the valve up off the tappet and tap on the old valve head to at least get the keepers to drop out. Then I could just lift the old valve out and get the spring off. Even then the guides had to be driven out with a hammer. I bought a 1 inch flexible hone to dress the guide bores, so hopefully I won't have any problems installing the new guides. Exhaust valves were somewhat easier than the intake for some reason. I bought a Neway valve seat cutting tool (used ebay), and I thought it took a 45 degree cutter for these seats, but when I looked at the cutter after it arrived it's in fact a 46 degree cutter on one side and 31 degrees on the flip side. Anybody know why there's 1 degree difference? Is this an appropriate seat cutter for 8N valve seats?
Thanks!

As for the 1 degree difference that is common valve seating methodology. The seal between the two sealing surfaces essentially becomes a narrow line of contact for the initial seal. After some time it wears in across to entire width of the seat. The difference is so slight that machinist bluing will get wiped of the entire seat surface when the valve is rotated against the seat with slight hand pressure.

 

[steveh1155]

I was getting the block cleaned up and saw this crack. This is at the center bolt on the valve side of the block. Is there any chance just some sealer on those head bolt threads would be enough that the crack wouldn't cause any problems?

 

[HarryVanderpool]

Yes. Not the end of the world.
Next thing to do is buy yourself a brand new. sharp, 12" flat file.
Lay the file on the deck, and WITH YOUR FINGERTIPS, move the file across the deck lightly in all directions.
Don't go all "King Kong", you're not filing the deck, you are locating high spots.
You will begin to notice high spots around bolt holes for sure.
You can measure with a straight edge and feeler gauge if you wish.
Once you are sure of high areas, you can gently lower them, again using minimum force.
Same procedure on the head surface, although you may prefer to just have a machine shop surface grind.
O.K, I'm ready for my whipping.
Let the flames begin....

 

[steveh1155]

I looked at the crack a little more closely and now I see that hole with the head bolt threads is open to a common coolant gallery that's shared with the hole to the left so now I'm thinking I just need to use some hi temp thread sealant on all the head bolts. When this tractor was running last fall, I never saw any oil or coolant leaking anywhere on the motor. Any recommendations on a head bolt sealer? Always had a slight amount of oil residue in the radiator and never anything in the oil.
I had to order a magnetic base for my dial indicator so I could do a proper setup of the exhaust rotator valves, so meanwhile I'll continue to get things cleaned up and use my mill file to check for high spots on the block. I bought the "soft" head gasket that j-u-s-t-8-n-s had and have a can of copper coat spray that I could use on the head gasket...is that recommended or not?

 

[BodaciousGaming]

I looked at the crack a little more closely and now I see that hole with the head bolt threads is open to a common coolant gallery that's shared with the hole to the left so now I'm thinking I just need to use some hi temp thread sealant on all the head bolts. When this tractor was running last fall, I never saw any oil or coolant leaking anywhere on the motor. Any recommendations on a head bolt sealer? Always had a slight amount of oil residue in the radiator and never anything in the oil.
I had to order a magnetic base for my dial indicator so I could do a proper setup of the exhaust rotator valves, so meanwhile I'll continue to get things cleaned up and use my mill file to check for high spots on the block. I bought the "soft" head gasket that j-u-s-t-8-n-s had and have a can of copper coat spray that I could use on the head gasket...is that recommended or not?

I had a crack behind the dry sleeve of #3 cylinder that I smeared a little JB SteelStik putty into before driving the sleeve home. No issues post startup. I wouldn’t worry about that crack since it goes from the water jacket to the water jacket. Nor do I think it’s severe enough to compromise head bolt torquing. I used some blue RTV on the bottom threads of every head bolt like I’ve seen periodically recommended, as well as the smearable tube of copper coat (heavily recommend the spray stuff btw) on the head and exhaust manifold gaskets. No leaks to report so far.

 

[DanielW]

It'd probably be fine with nothing done except sealing the threads. But if it were mine I'd be safe and vee out that crack with a die grinder, clean well with brake-cleaner/acetone, and smush some high temp goop in there - trying to force it as deep into the crack as I could. Then trim flush with a razor and put the appropriate sealant on the threads before assembly. Not uncommon to find cracks like that, or similar ones between cylinder sleeves on lots of old tractors. And usually it's not the end of the world. Especially on a smaller gas engine like an N.

Lots of folks use a hardening epoxy for these type of cracks. I have a slight preference to something that remains a little more rubbery like a high-temp RTV, because I figure when the block heats, the block is going to expand at a different rate than epoxy and the crack might open up. But that's just my own thinking. Folks have good luck with epoxy, and I'm sure either would do fine for you. For larger engines, more significant cracks, or higher-compression diesels, it's not uncommon to cross-drill the block form side-to-side between cylinders (right through the water jackets). and use threaded rod with some nuts & gasket washers to pull the block together and hold the crack closed. Did that for a Massey 555 diesel I had. But I don't think that would be necessary (or even possible) on an N.

 

[steveh1155]

I've decided to use Gasoila soft set on all the head bolts that go into a coolant gallery. It has a good high temp rating, doesn't set up hard and I already had some on hand. I got the valves installed yesterday, and later today when it warms up a bit I'll get them adjusted, which is a little easier with the head off. Hopefully I'll get the head on as well today. The head gasket I received is a Tisco soft fiber gasket silver colored, and both sides look identical to me, even the metal ring that goes around the cylinders is the same on both sides, since this gasket looks symmetrical and isn't marked for block or head side, maybe doesn't matter which side goes down?

 

[DanielW]

One thing to keep in mind with those aluminized N gaskets: They work well, but a lot of them don't have all the holes for the head studs perfectly located, and they sometimes rub or bind very slightly on the studs when you go to drop the gasket on. Have all the studs in-place (or thread in the bolts through the gasket if yours has been changed to bolts like some were) and make sure the gasket drops smoothly and cleanly onto the block with absolutely no binding on any stud/bolt. If it rubs/binds at all on any hole (even if only a slight amount) you'll want to file the hole in the gasket a smidge to let it drop on cleanly.

Although you may think that it's only rubbing slightly and it'll just clamp down nicely when you torque it down, even the slightest binding around a stud will cause the gasket to 'bulge up' slightly around the offending stud when it's torqued, and the head won't seat fully at that location, sometimes causing a head gasket leak a that location.

 

[steveh1155]

One thing to keep in mind with those aluminized N gaskets: They work well, but a lot of them don't have all the holes for the head studs perfectly located, and they sometimes rub or bind very slightly on the studs when you go to drop the gasket on. Have all the studs in-place (or thread in the bolts through the gasket if yours has been changed to bolts like some were) and make sure the gasket drops smoothly and cleanly onto the block with absolutely no binding on any stud/bolt. If it rubs/binds at all on any hole (even if only a slight amount) you'll want to file the hole in the gasket a smidge to let it drop on cleanly.

Although you may think that it's only rubbing slightly and it'll just clamp down nicely when you torque it down, even the slightest binding around a stud will cause the gasket to 'bulge up' slightly around the offending stud when it's torqued, and the head won't seat fully at that location, sometimes causing a head gasket leak a that location.

Good to know, I'll check that. I was going to spray the head gasket with some copper coat, but since aluminum and copper react badly together perhaps, I should skip that step?

 

[DanielW]

Good to know, I'll check that. I was going to spray the head gasket with some copper coat, but since aluminum and copper react badly together perhaps, I should skip that step?

I'm hesitant to comment on that one, because there are a lot of strong opinions on what sealant (if any) to use. You'll find folks have used just about anything, and in most cases it works dandy regardless of what's used. Never used cooper-coat on an N myself, but other folks folks on here have with no complaints. So if I had some copper-coat handy, I wouldn't hesitate to use it. I'm not even sure what alloy those N head gaskets are. They're called 'aluminized' head gaskets, but they're certainly not any pure/common aluminium alloy, and I'm thus not sure how badly (If at all) they'd react

Don't think you can go too wrong with almost any high-temp sealants on an N head (and lots of people don't use any). But that's just my opinion.

 

[soaked]

Hi guys, I haven't used coper coat before either, and have also had the metal head gasket where the holes don't all line up.
Here is the older FO-4 manual on the left, and Fords later Attachment #3, on the right, giving a different torque sequence. I made a drawing of the new version, and put the paper right on the head, so as to not loose track...

 

[steveh1155]

Well, I've got the new valves installed and did the 3 angle cuts on the inserts then lapped them and checked with the dye. Everything looked good. I put the head back on and got it torqued down and then checked compression again. I ended up using the copper coat on the head gasket. The compression numbers were still pretty disappointing,
#1 30lbs
#2 35lbs
#3 30lbs
#4 90lbs
Sounds like stuck rings doesn't it? I poured some ATF in each cylinder and checked it the next day.
#1 50lbs
#2 50lbs
#3 60lbs
#4 90lbs
I gave them the ATF treatment again and let it set another day, and today when I checked compression I got,
#1 60lbs
#2 60lbs
#3 90lbs
#4 90lbs
At least it's going in the right direction! I'll check again in the next day or two then decide if I want to just go ahead and install new rings and liners. I think I just need to remove the front axle and drop the pan to do that and I'm already most of the way there (and unfortunately remove the cylinder head again). Meanwhile, the grass I need to mow is still growing quickly.

 

[HarryVanderpool]

Is the throttle plate and choke WIDE OPEN when you are checking compression?
Also, for those following along; Neway recommends NOT lapping the valves after cutting seats.

 

[steveh1155]

Is the throttle plate and choke WIDE OPEN when you are checking compression?
Also, for those following along; Neway recommends NOT lapping the valves after cutting seats.

The manifold wasn't on when I checked compression. What I read from Neway was that it doesn't help to lap after cutting, but it also doesn't hurt anything as some people do a light lap to check tolerance between the two surfaces (as opposed to dye). Apparently lapping will result in a better seal INITIALLY, however after a very short time it becomes mute as the two surfaces are "peened" together. This was from an interview I read with a Neway representative from about 4 years ago.

 

[560Dennis]

Crack on right is going to continue till it reaches the hole. Drilling a hole at end cracks will eliminate.
Then lock and stitch it .
Link to how that’s performed.

Engine Block & Cylinder Head Crack Repair MA,CT,RI,VT,NH,ME,NY,NJ

Engine Block & Cylidner Head Crack Repair. metal stitching, pinning and welding. MA,CT,RI,VT,NH,ME,NY,NJ. 603-742-8812

www.rlengines.com

 

[DanielW]

What is the intent with the ATF in the cylinders? Confirming if valves or rings are the problem? Or freeing up stuck and carboned-up rings? As you probably know, the way to confirm whether valves or rings are the cause of low compression is to put some oil in the cylinders and check again. If the compression goes up, it's a ring problem. If it stays pretty much the same, it's a valve problem.

Seeing that the numbers went up with ATF in the cylinders and knowing you just had the valves done, it sounds very much like worn or stuck rings. Might be time for a ring/top-end job. But I'd try to get the rings unstuck and get rid of some of the carbon in them first. That might do the trick without more parts and tear-down. But you'll need to let them soak in something thinner and more potent than ATF. And you'll also need to run it for a bit with a load to really clean them up and set the rings. I prefer a good dose of a high quality penetrant in each cylinder. Deep Creep is good. The Delco penetrant GM sells is even better. A mix of ATF and acetone would probably be good too. But ATF alone won't do much apart from confirm where the problem is.

Spray a healthy dose of your penetrant of choice in each cylinder through the plug holes, let soak for a few days, repeat, let soak, then fire it up and run it with a load for an hour or so. With any luck after running for a bit with the penetrant having worked into the rings and broken down any carbon, the rings will free up and help those compression numbers.

 

[Jim.ME]

Just curious, I don't see setting the valve clearances mentioned. What are the valve to tappet clearances?