This probably talked about many times, but I'm new to the Model T. I took the exhaust manifold off tonight and saw what looks like the infamous two piece valves. Should I change them, and is it a difficult job? Stainless or not?
If you are rebuilding the engine, yes. If it runs OK now and does not need valve job, leave it alone. I have never thought I needed stainless valves. Also,be prepared to be opening up a can of worms.Everyone that owns a T needs to buy a service manual.
I was interrupted before. By can of worms I mean the following. It will probably not just need new valves. That will also mean new tappets. Probably oversize on one or both. That means reaming. Oh, gee, the cylinder walls are worn, and I can wiggle the tops of the pistons.New pistons, bored out. Alas and alack, the rods are worn. Rebuilt rods. Now, those mains, and that crank is already .025 under.......
If it were mine I'd replace them, but then again, I'm pretty anal when it comes to my engine.
Here's a thread from only a few Months ago...I report, you decide.
they make great drawer knobs, just tap threads on em. but they do not make good valves
When I got into this hobby, (over 45 years ago), those old valves were about a half century old, and may have still been okay to run for many more years. Or not. At nearly a century old, they have had twice as many years for thermal changes, humidity ingress, and corrosion to attack the bonding between the steel stem and cast head. Forty years ago, I knew enough people that had broken two-piece valves that I considered it unwise to use them then. Today, I wouldn't consider running them. They are second only to the rear end thrust washers for my "must upgrade" list. Most things, I like to run original stuff as long as it is fairly good. I run original crankshafts, cast iron pistons, original bearings (both Babbitt and roller/ball), wood wheels, pretty much you-name-it. Except Babbitt thrust washers and two-piece valves.
But, that is MY opinion.
Drive carefully, and enjoy, W2
Jim, sounds like DOOM and GLOOM!
What are you going to use your T for? Occasional rides at original T era speed,say 25-30 mph with frequent stops and slowdowns, or some grueling high speed tours?I agree that the original valves can fail. I've had it happen. So can an endless list of other components fail. I personally would be nervous on ball bearing front wheel bearings unless they were perfect. Yet I have known people that go like hell on them. With early hubs, too. I am not trying to be negative. But, when you unbutton an engine that may not have had major work since the Hoover administration you might not be able to stop short of a total rebuild. And I will always say not everybody's T needs a multi-thousand dollar engine rebuild.
Probably not more than 2 or 3 hundred miles a year. Easy driving under 30 mph.
Does it run OK now? If so, I would make sure my rear axle nuts are TIGHT, along with no excess play or wear in the steering, No loose or dry rotted spokes and a few other things. Drive it and enjoy it.
Runs great. Axle nuts thigh, no play in the steering and spokes are good and tight.
I've had one break on me. It was an exhaust valve back in 94 or 95. There was no forum then and nobody to let me know so I had no idea that they were prone to break so I only replaced the one valve. One might break tomorrow but the other 7 are still in there. I don't drive fast or to far though, but I wasn't when it broke either
I had one break back in the 80's while on a vacation to Hershey, 1st day out. Head did not come off, a wedge shaped piece broke out. What to do, park the car for 2 weeks. No, the guy at the camp ground had a T. Dug it his junk parts box, got a used valve and away we when. Did not do a valve job till about 1991. Can you run them? Yes. Should you run them? I do not any more, I change them in all my cars. They will not break when they are sitting in the shed, only when you are on the first day of a tour! All that said you can do what you feel comfort with. Dan
Everyone has their opinion. Until two years ago, I had an old original '25 pickup that had all original valves, pistons and everything. It all worked too. If it works leave it alone, fix it if it doesn't.
My opinion is, like Jim's above, depends on how you will use the car. On two I owned I opted for NOS two piece valves on rebuilds of very original cars so as to keep things stock. These cars were driven a few hundred miles a year at speeds of about 25 mph around the neighborhood. Re rear end thrust washers, it depends on the condition. I've seen them in pristine condition and left them alone. Granted most are in bad shape and need replacement, but not all.
To me, it is not a doom and gloom it is going to break and my car will be destroyed, or anything near that. Of the several people I have known to actually drop the valve head into the cylinder, a couple (I think actually three) did no damage whatsoever to anything but the valve itself. replaced quickly by another second-hand two-piece valve, and the tour day was continued.
Then, there are the others. At least three engines were effectively totaled. Broken pistons, bent rods, one bent rod cocked the piston so badly the cylinder was split lengthwise. A couple valve heads punched holes through the combustion dome of the head. And one block knocked the center main webbing completely out of the block when the piston ceased travelling upward.
To me, the potential risk is high, versus a rather low cost to probably avoid what could be extensive damage. Especially with rare early blocks. Proper replacement valves are not expensive (about the same cost as a new set of inner-tubes for the same car). And if you are on a really tight budget? Used modern valves can usually be had for nearly free that can be cheaply adapted to fit and work very well.
Just me, and I am a cheapskate.
Drive carefully, and enjoy, W2
Jonathon, are your manifolds still off? As I've stated elsewhere, I'm a bit rusty at this T thing, and have overlooked something important. If someone has mentioned this above and I missed it, sorry to be repetitive. Back in the day, and even now, some of the driving technique left something to be desired when it comes to spark advance. Those that chronically do not advance the spark erode valve stems.I have worked on engines where the stems in the exhaust ports were barely thicker than the lead in a pencil. These, of course must be replaced.
Jim, the stems do not seem eroded.
You can do a total valve job with the engine in the car. Even grind the valve seats with a Portable grinder. I had an engine that was rebuilt around 1980 that had some poor quality valves that mushroomed. One afternoon and new valves were in place. Of course I was fortunate that there were adjustable tap pets in place and I didn't have to grind the stem ends. With two piece valves, you probably have non adjustable tap pits. Not a major problem, but you will need a valve grinding setup with the stem grinder.
I wouldn't let the worry about opening a can of worms worry you. Replacing the valves will not harm any other components of you motor.
I have read of different clearances from the end of the valve stem to the tappet. What should they be for the intake and exhaust?
When i had my engine apart i updated my valves to stainless, added adjustable lifter's, and adjusted both the intake and exhaust to about 0.012-0.014., and my engine runs like a top. Do your own research, but i can tell you Glen Chaffins post on adjusting lifter's is a must read on this topic, that's how i did mine.
Woke up for a nature call.Your old tappets will have a wear pattern from the stems pounding them.Other words, cupped. You can't get an accurate measurement with a feeler gauge. And far be it for me to suggest on here you should do anything half-assed.Provided your cam is not too worn, you should set the valvesJim Eviston by piston position. Do a search for it.
I type slow. And fight sPELLCheck. Agree with John. You could probably use plastigage in there to get clearance.Nevef done it, may not work.
Johnathan, if it runs well then I would leave it alone and enjoy it as is. If a valve breaks it is unlikely to destroy your engine. In fact, I have never seen that happen with a stock cylinder head. Plenty of room in there. Might make a little noise but will not grenade the engine. If you take it apart right now you will probably find it needs everything, same as it will if a valve breaks, so why not just roll with it?
When it comes to things like this, I am a risk taker. I KNOW what COULD happen, but I am willing to accept that risk, believing the chances of it happening are slim. I wouldn't do it on a 1909 engine, but I wouldn't think twice about leaving them alone on a 1918 engine until other circumstances made me open it up. At that point, yes, I would change them out.
But that's just me.
Jonathon, I have a valve reamer that is .015 over o/s that you can have if you decide to ream. It is the "solid type". It has a pilot section on it, and just needs a tap handle to clamp it into.Yours if you need it because yer a newbie.
Thanks Ray. Still not sure. Like I said it runs great.