Is it possible to identify if you have two piece valves without removing the head? My engine was rebuilt in the late 80's by a pretty prominent engine guy in our area, but who knows if he did indeed update them. If i can get a light in there, would the two holes on the valves indicate a two piece, and would no holes represent a one piece unit?..Thanks.
(Message edited by Jp_noonan on March 01, 2015)
no holes is a good sign, but i have seen one piece that have the holes too. rebuilt engine would surely mean new valves to anyone in the business. i think you can see the bottom of the valve thru the ports with out taking the head off
About the only way to know is to remove the manifolds. Usually that is not a major project. With the manifolds off, you can look in through he ports and see the hideous bulge indicating two-piece valves. I call it the "hideous Bulge" because I do not trust two-piece valves. I have spoken to T owners even in recent years that still use them. But the risk of destroying an engine is just way too high for something that cheap to replace.
Often, you may be able to keep the exhaust pipe connected and pull things to the side just enough to see in with a penlight to see what type valves you have. And check them all. I have taken a couple T engines apart that had only one or two two-piece valves in it. (I have pulled the manifolds over to change gaskets a few times.)
A simple fact, is that for the most part, referring to valves as "one-piece" or "two-piece" is a misnomer. Nearly all "one-piece" valves are actually made from two pieces welded together. What we refer to as "two-piece" valves are a cast iron valve head cast onto a steel stem. It really isn't that different. When the valves were new, they probably worked just fine 99.9 percent of the time for many years. The risk comes with age. Moisture has had an opportunity to get into the casting and create rust. That in turn can loosen the head from the stem, or even worse, rust expansion enough to begin a crack in the cast head. Possible unknown abuse or damage adds another layer of failure possibilities. The older they get, the more untrustworthy they become. I didn't trust them forty years ago. At about the same time-frame, a friend of mine lost a valve head on a tour.
And in all fairness to reality. Replacing two-piece cast-head valves with so-called one-piece actually welded valves is NO guarantee that a valve won't destroy your engine. The conditions were more extreme. A model T is not likely to do this, but I have heard of one that did. I still like the numbers. NOT worth the added risk to run the old two-piece/cast head valves.
My dad rebuilt a Chevy V8 for his '68 Chevy pickup. It was a nice engine with excellent valves (supposedly). However, the rear end was geared way too low. I have not been able to find any numbers on it, but I am sure I have never driven any other highway vehicle geared this low. It should not be driven over 55 mph. But my dad was always late, in a hurry, and would push the poor thing to over 70 mph.
Well, one day, late, flying up a steep hill as fast as he could make it go, one valve head broke off. Bent the rod and broke the piston both badly. The cylinder had three cracks running down the full length top to bottom. The valve head wound up inside the water jacket portion of the cast iron cylinder head (I was surprised that the aluminum piston held up enough to hammer it clear through the engine head casting).
The engine was pretty destroyed. He got another engine, rebuilt it and put it in the truck. It took a long time. Long story about that.
Drive carefully, and enjoy, W2
I'm unfamiliar with the concept of welded one piece valves, I've only seen them being hot forged in a press out of one piece of steel.
This thread show multiple images of the 2-piece valve.
I'm wondering if one could go in the back of the exhaust mnanifold w/one of them new-fangled digital inspection cameras, w/the long, thin flexible probe, to look at the valve stems.
I see them gadgets advertised in the fliers all the time.