Non rotating tappet

[Ronmar]

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...

[BruceM]

Thanks for the clarification on the springs, Ronmar.  I'll go "fishing" at Ace on my next trip to town.

[mobile_bob]

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

[Tom Reed]

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.

[fabricator]

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.

[akghound]

..., 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

[fabricator]

24/7, I intend to run it for the entire month and then see what everything looks like.