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By 1960fordf350 - 5 Years Ago
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What causes the valves to rotate? After pulling my heads and lapping the valves, I noticed the ends of a couple valves clearly show the rubbing of the rocker arm straight across the end of the stem. These valves were brand new when I put the heads on my engine 400miles ago. On those valves I can see a straight up/down pattern on the shaft. There were all new guides installed in these heads. none seem too tight to prevent rotating. So are these valves bad, or are the rockers?
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By MoonShadow - 5 Years Ago
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The design of the mushroom lifters causes them to rotate thus turning the pushrod. This is the way it's supposed to be for the best oiling.
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By DryLakesRacer - 5 Years Ago
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I did not know our valves rotated. MoonShadow described the lifters and pushrods which have no contact with the valves. There are engines with valve rotators on the top of the springs.
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By Joe-JDC - 5 Years Ago
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A lifter turning and pushrod turning have nothing to do with valve stem rotation. They do not come into contact with the valve stem and cannot affect the rotation unless the rocker arm is not centered and pushing the stem at an angle. Spring harmonics with too soft springs will cause the valves to bounce off the seat, or loft over the camshaft lobe. Your valve with the nice even pattern on the top is working exactly as it should. If the tops of the valve stems show a pattern of continual rotation, the spring rate was wrong for the camshaft lift and/or not enough seat pressure at installed height. Joe-JDC
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By oldcarmark - 5 Years Ago
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Yes, the valves do rotate under normal operation albeit slowly. Some valves have rotate mechanisms to ensure they rotate at a predictable rate.
The rotation action helps keep the valve and seat clear of debris to ensure good sealing. I think Ted will confirm this when He reads this Post.
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By MoonShadow - 5 Years Ago
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Once again I get caught reading too fast and missing the issue. Sorry guys.
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By KULTULZ - 5 Years Ago
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Valve rotation is as a result of valve-train dynamics. There is nothing to prevent the valve from rotating.
Rotation will increase with engine speed. Thai is why a HD Engine will have valve rotators as they are operated at lower RPM and subject to much more cylinder heat.
Let's see if I pass the quiz once TED showers and shaves ... 
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By 1960fordf350 - 5 Years Ago
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I appreciate the feedback. Any truck info I've read has mentioned rotators on industrial and truck engines. Someone spent good money on these heads before I got them. New valves, new guides with spring loaded valve seals, double springs, and hardened valve seats. They didn't lap the valves, just put them in. They must've assumed they would seat themselves. After a compression and leak down test, I had one cylinder down. The hardened exhaust seat had a punch mark in it leading to the leak. Lapping took the mark out, so I lapped them all. I just didn't want to have to pull the heads again for an issue with the valves rotating
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By darrell - 5 Years Ago
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i dont lap my valves but i do check them.i turn the heads over and install the plugs and fill the combustion chambers with water and leave them overnight.any leaks will show.
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By Ted - 5 Years Ago
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1960fordf350 (2/21/2019)
What causes the valves to rotate? After pulling my heads and lapping the valves, I noticed the ends of a couple valves clearly show the rubbing of the rocker arm straight across the end of the stem. These valves were brand new when I put the heads on my engine 400miles ago. On those valves I can see a straight up/down pattern on the shaft. There were all new guides installed in these heads. none seem too tight to prevent rotating. So are these valves bad, or are the rockers?
The springs themselves have a natural tendency to rotate due to their spiral nature. The idea behind the original two piece valve spring retainers is to promote valve rotation. Going with single piece retainers does slows that rotation down but does not stop it. In the grand scheme of things, you want the valves to rotate to promote even wear at the seats as well as helping to keep the seats and valves clean. Badly worn rockers can create enough drag at the valve stem tips to inhibit valve rotation. Here are some videos showing the valve springs rotating on performance engines.
https://www.youtube.com/watch?v=WtqDHJDN79w
https://www.youtube.com/watch?v=019Jyn9oB5k
https://www.youtube.com/watch?v=ijYC8LbB5ZI
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By FORD DEARBORN - 5 Years Ago
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Greetings to all: I'm not an expert on the intricate dynamics of valve train operation but will try to offer a few things from an old memory. A coil spring has a natural tendency to tighten the coil, that is, reducing it's outside and inside dimensions, when compressed. The opposite happens when released. I may have the direction of coiling and uncoiling wrong but the point is either direction will produce a rotational effect. There are, as we know, one piece retainers and 2 piece retainers available. With the 2 piece retainers, it's the inner section that is often referred to as a rotator. At some speed there are natural harmonics going on, and with the natural "coiling/uncoiling tending to rotate the spring and the ability of the spring retainer free to turn against the inner piece, rotation can happen. Not sure how constant or predictable it is. Adding an inner damper spring and/or changing to1 piece retainers, one or both may prevent the natural rotation tendency. Find something similar to an old fashioned door closing spring, secure one end in a vise, tie a short length of string on the springs free end and stretch it. It soon becomes evident how much the free end rotates. Again, I can't remember which action produces what direction of rotation. Just some food for thought, thanks for reading, JEFF..........................
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By FORD DEARBORN - 5 Years Ago
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Ted was faster at the trigger than I. Well said Ted.......................
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By Joe-JDC - 5 Years Ago
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I will agree that spring harmonics cause valve rotation, but the pushrods and lifters do not. Joe-JDC
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By FORD DEARBORN - 5 Years Ago
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Extremely amazing videos. I would think an engine with solid lifters would tend to promote valve rotation more so than an engine with hydraulic lifters? Thanks Ted for the links. EDIT: I base this on the fact that for a certain time during the cycle, the rocker is at zero contact with the valve stem allowing more freedom of movement.
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By Tedster - 5 Years Ago
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"The intake and exhaust valve assemblies are the rotating type." So sayeth the Ford Shop Manual.
Eickman's book pg. 25 sez "The valves in a Y-block were equipped with rotators to pro-long valve face life. The rotator was simply a tapered sleeve in which the keepers were seated. This sleeve was in turn seated in the retainer. The rotator served to reduce the contact area with the retainer, which enabled the valve to turn in the retainer and valve spring."
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By DryLakesRacer - 5 Years Ago
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In all the photos you can see the "paint" removed from springs and can just imagine what the bottom edge of the spring that rests on a cast iron head is doing. These are good reasons for using steel shims under valve springs and buy a very very good oil filter,,....
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By KULTULZ - 5 Years Ago
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