What do you do when you have a tappet that just won't spin? I took it out and polished the cam follower end, polished the tappet body and nothing sometimes Get some random movement, the exhaust tappet rotates about 100 rpms, but the intake just won't turn, if I run the adjuster down so it just starts to spin a little the valve is open on the compression stroke.
What is supposed to make the tappets spin anyway?
Camshaft ground half a thou out of flat, sometimes mechanical rotators are used. Non rotating is usually not a big deal. I wouldn't worry about it.
In propane gas car and truck engines we used to remove the rotators as a rule, with no ill effects. It was found that valve wear actually increased with valve rotation in dry gas engines..
I believe the cam is off center of the lifter causing it to rotate. If the lifter is not perpendicular to the lobe it will confuse the lifter. There are many techniques to promote lifter rotation. I usually loosen the lifter guide clamp just enough so you can rotate the lifter guide then while the engine is running rotate the lifter guide until you see rotation tighten the clamp and see how it behaves. Tightening the clamp may stop the rotation so you try another sweet spot. Do not over tighten the clamp. It will distort and put clamping pressure only on the one inside causing the guide to tilt. It does not take a lot to hold it there. Put a white paint mark on the exposes lifter and you will be able to see at a glance it is rotating. Of course there are other reasons why......
Lots of engines have a little paint on the outside of the tappet that hangs up and prevents it from rotating. It might be a good idea to scrape the paint away so you're sure it's not interfering. Beyond that, maybe polish the sides of the tappet with 320-400 grit wet/dry sandpaper and kerosene or paint thinner to make sure there aren't any scratches/burrs that are hanging it up. And look inside and make sure your cam lobe is contacting the lifter face off center. Some engines have come into the US with cam lobes misplaced on the camshaft so that they are dead centered on the lifter surface, keeping it from rotating.
All that said, this is a slow speed (by modern standards) engine and I doubt that, even if the lifter didn't rotate, you'd accumulate enough actuations of the cam lobe against the lifter to cause troublesome wear.
Quinn
And then there are lifters where the face is not ground perpendicular to the bore. If that is the problem you'll need to find someone with a post grinder and have them chucked up in a lathe and ground square.
Right. The lifters I've seen have all been heat treated. During heating, if they are allowed to get too hot, they can sag to one side or the other. I've read here that others have found lifters that didn't turn true, and that's the only way I can envision that happening.
Quinn
in manufacture the lifters are machined square/plumb and all good, however
during heat treat, which is likely done with a flame (oxy/acetylene) with the lifter body standing in a jig
and submerged in water just to where the face is barely covered in water...
the flame is used to get the face red hot, the pressure of which displaces the water and when the flame is taken
away the water rushes back over the face and hardens the face surface...
done right there is little warpage, however
i suspect they are heated with a torch and thrown in a bucket of water, which will warp the face off of perpendicular to the body
of the lifter... this can be corrected in the final machining process which the indians seem to avoid for reasons likely of saving a few
penny's
done right the final process will first grind the lifter face perpendicular and flat, then followed up in a centerless grinder sort of machine
which will leave the face a bit convexed, anywhere from a half thou to a thousands high in the center...
the cam lobe should also be ground a bit high on one side of the peak of the lobe, this high side mates well with the offset and convexity of the lifter and together they assure proper lifter rotation and long lifter and lobe life.
which on a slowspeed engine is probably something on the order of a few hundred years :)
bob g
My lifters looked ok but I had them ground flat anyway. No heat treating afterwards and after 4000 hours there is no sign of wear. I also polished the lifter and guide and had to shim the cam internally with a washer to make things right. The red dot in the pic shows where I put the washer.
(http://genedevera.com/temp/cam.jpg)
Thanks, Geno
I love that white crankcase interior, Geno, wish I had one! Mine is dark green and swallows all light, so it's very hard to see anything on inspection.
Quote from: Geno on January 06, 2012, 03:13:48 PM
My lifters looked ok but I had them ground flat anyway. No heat treating afterwards and after 4000 hours there is no sign of wear. I also polished the lifter and guide and had to shim the cam internally with a washer to make things right. The red dot in the pic shows where I put the washer.
(http://genedevera.com/temp/cam.jpg)
Thanks, Geno
Great Pic Geno! You can see the offset on the cam to lobe......All the other reasons they don't rotate nice we can't see. Mine looked like they were faced on a lathe with worn out tools...soo I ground them perpendicular and all ....it still didn't rotate! I ended up having to do what Geno did only I found the lifter guide is not bored perfectly to the outside. I rotated the lifter guide and found the spot that tilted the proper direction. Then I found if you over tighten the tin clamp it won't put pressure on centerline it deforms and will put pressure on the inside only and with any clearance between the guide and the block with a mushy gasket causes it to tilt. ....and...I think I used to many ands..:) The point is any misalignment will cause a problem....You will find a spot where the star will align and it will spin :)
(http://i260.photobucket.com/albums/ii31/xyzers/xyzers%20stuff/clampview2.jpg)
Ok, that sounds like what I'm gonna try first and if it don't work, I'm leaning toward not worrying about it ;)
You say it rotates when you take out the valve lash? Does it rotate if you put a little pressure with your finger down on the rocker arm above the pushrod while running? If so, something like this with a hardware store compression spring might work for you. Worked for me anyway, had the same issue and nothing I tried worked to resolve it untill I tried this... That little bit of pressure is all it takes to rotate mine. That spring applies that force while still maintaining the proper valve lash. Also helps to be at full running temp. When warmed up fully they rotate much easier.
http://s270.photobucket.com/albums/jj85/rmarlett/?action=view¤t=DSCF0023.jpg&mediafilter=noflash
Yeah, I ran it for a week straight and it rotated the whole time, not fast 20-30 rpms maybe, now it won't unless it's opening the valve in the compression stroke, maybe I'll try the spring thing.
Ronmar, how are the springs held in place? It looks like a little post glued to the valve spring cap?
I'd like to try this as I have always had excessive valve clatter (tappet noise, really), and if I manually hold the rocker lightly down on the tappet (as your spring does), the clacking goes away. It is the loudest sound in my engine room!
XYZER you are (as usual) spot on ;) What makes a lifter spin when acted upon by the cam is the point of contact being off center form the centerline of the lifter bore, not the finish of the lifter or anything else. If the lifters guides are held correctly (and they are not with the Indian tin foil hold downs) and the cam lobes are in he correct (off-set) position under the lifters they are going to rotate unless something else is off by a very large margin. A look down through the lifter guides with lifters removed will reveal the real problem with an engine with rotation problems, at least on the handfull I have been into. Exhaust lobe is off set from center, intake is very close to dead center one every Indian engine I have laid my hands on. It seems when the subject is brought up it is nearly always the intake that is not spinning? Must be every cam is made (wrong) on the same jig? I wished I would have taken pictures of my Dursley built engine vs the 'roids in this respect, it would then be obvious. Both lifters spin like crazy on my Dursley engine and the off-set is markably more on it than any Indian cam, again what I have laid my eyes on. All this does not mean that the roughly made Indian lifters do not need corrected for both finish and trueness. It also does not mean that if you have made them spin by other means that you have done wrong. I have shifted the entire cam as above myself.
My point here being the lifter finish is not the prime mover behind rotation, point of contact being off set from center is. And there are indeed several ways to get there besides the prim and correct way.
Sorry about the blurry pic, that is actually 2 springs, one inside the other. Had these from another project in the hardware bin, they were both pretty soft and neither alone was quite enough by itself so I doubled them up. Nothing holding them there but their own spring tension. They have been there quite a while now and havn't moved a bit.
I initially experimented with a piece of music wire with a bent hook on each end, and a tension spring. I put this alongside the pushrod, hooking one end of the wire under the tappet holddown bracket. The other end hooked to the end of the tension spring, and the other end of the tension spring I hooked to the rocker arm near the adjuster setscrew/locknut with a ziptie... This worked well also then I cooked up the pictured solution which was a little cleaner looking and simpler...
Not sure how far the cam lobes are offset from center of the tappet, but sounds like a likley reason. Mine would almost rotate unassisted if I rotated the guides just right. They would appear to rotate about 1/4 turn then shift back to where they started after the cam passed. This indicated to me a misalignment of tappet face to cam, it could also be like mentioned, lobe too close to center of tappet face, so as the cam went past the peak, you actually get a reverse torque applied. Without the spring tension, the best rotation I could manage, I could never maintain when I tightened the "tin foil"(perfect description:)) hold down bracket. Was going to machine out a solid one like that pictured, but never got around to it. The one pictured looks great...
Also you need to lap the pushrod ends into the tappet cups and rocker adjust screw balls into the pushrod cups. If you roll the cam till it puts a pushrod under tension, the pushrod should still rotate smoothly by hand. New, when under load, mine were rough and would stick. You can lap them in place with some valve compound in the cups and a piece of string/shoelace wrapped around the pushrod. You can roll the crankshaft to control the tension you are applying to the pushrod. I could not spin mine with the shoelace under any real cam tension. I had to gradually increase tension as the parts smoothed out. A pair of vise grips can be used to gently hold the tappet from rotating under low cam pressure untill you get things lapped smooth. Pull the lace back and forth a bit, then rotate the tappet and the rocker arm adjuster screw so the cups and balls polish evenly all around. Rough pushrods could be adding enough drag to the process that the tappets cannot rotate...
Thanks for the clarification on the springs, Ronmar. I'll go "fishing" at Ace on my next trip to town.
i would strongly disagree,,, lifter and lobe finish is very important to proper operation or rotation
of course if there is plenty of offset the lifter should rotate, however there are many other engine's with ample offset that
don't rotate and will flatten the lobe of a cam (no not flat in the classic sense, but flat in that the .001 offset grind will wear away, along
with the convex face of the lifter.)
if the offset is incorrect, correct that first and see if the thing will then rotate
if it still doesn't then do the guide rotation thing and see if it will now rotate, if it still doesn't
then check the lobe and lifter face and correct as needed.
me i would certainly do all these things to get the lifters to rotate, it is important to more than just the lobe/lifter face interface
the pushrods also benefit along with the rocker adjusters from proper rotation.
bob g
I'll second Bob G. My intake lifter did not rotate, so they were replaced with a blue printed set from George and now the work fine. I'd suggest checking them for finish and that they are straight and square to the cam before applying bandaids. The lifters can be pulled without removing the cam, so it's not to big a deal to check them.
Oh I pulled the lifter and stuck it in the lathe and polished it to a mirror finish, I rotated the holder as suggested above and found somewhat of a sweet spot, it rotates now, slowly but it rotates and that's good enough for me, it has been running now for two weeks straight.
Quote from: fabricator on January 20, 2012, 05:40:33 AM
..., it has been running now for two weeks straight.
Is it running around the clock? We live off grid with only gen power. It is shut down at night and lots of times during the day. Most use is early morning and ofcourse dusk to bed time.
Ken Gardner
24/7, I intend to run it for the entire month and then see what everything looks like.