Some Observations about Solid Lifter Valve Adjustment

Top End (cylinders and heads)
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Cotten
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Some Observations about Solid Lifter Valve Adjustment

#1

Post by Cotten » Mon Apr 20, 2009 12:53 am

Some Observations about Solid Lifter Valve Adjustment:

It is the nature of metals to expand and contract with heat. And different metals expand and contract quite differently.

Knucks top ends (and Sportsters of course) are all cast iron. Their pushrods were steel, which has a very similar thermal expansion coefficient to cast iron. Thus the cylinder/head assembly and the pushrod expand roughly to the same proportions.
So the cold clearance should be pretty much the same as a hot one.
And everyone assumes that at running temperature, the pushrod should turn freely to oil itself, but have zero lash to the rest of the valve train.
By 'lash', I refer the clearance between the pushrod and the rest of the valve train.

However the motor does not all heat up at the same rate: The cylinders and heads rise quickly, but the pushrods must wait for conduction and oil to warm them, so the lag creates lash. That's where the noise, and pounding upon the valve train originates.

So a motor with solids will start out relatively quiet, but begin to 'sing' as it warms, and eventually come to equilibrium with a pleasing tickity-tack, if all is in order and the final lash is minimal.

And it should be obvious to all that hydraulics were invented to overcome this phenomenon, as all lash is automatically taken up. Needle'd roller bearings were not introduced until these 'cushions' went into production, as their longevity can be quickly compromised by crystallizing hammering..
The persistance of use of solids can be attributed to several factors: The early models have no provision to oil the successful later design of hydraulic lifter, their simplicity eliminates the chance of a lifter failing, radical cam profiles require them,... and last but not least,... they are cheap.

So once our choice to go "solids" has been made, we must install them in a manner that reduces the lash to minimize the long-term effect of its hammering upon the hardened surfaces of the rockers, valve stem cap, tappet rollers, and cam lobes.
With the all-ferrous motors, things even out nicely and the range of adjustment is friendly and practical, as what-you-feel should be what-you-get.
But add aluminum heads, and the give and take of expansion and contraction gets a little confused. For reasons that are not intuitive, the pushrods get looser than they should.
So these motors start out with a tighter initial setting than iron motors, in order to compensate and achieve a zero-lash situation at full running temperature.

If we also toss in the wildcards of aluminum pushrods, then the initial setting may need to be as tight as possible without losing compression, lest the difference in expansion result in dangerous degrees of lash when hot. It is not unheard of to have one fly out under heavy acceleration, although it is invariably blamed upon an 'pushrod nut came loose", when it was really the nut on the handlebars to blame.

So some more things about adjustment should be taken seriously:

The valves should be as close to equal as possible (although many choose to stiffen the front exhaust a tad more than the rest, and some choose to stiffen both exhausts, at their own subjective risk.)

If a bind is encountered at any point when turning the pushrod in its sockets, then something is bent or blemished.

Adjustment upon a cold motor is most practical and reproduceable, but inspection thereafter of the lash on a fully-warmed motor is more than prudent, especially if it sounds like a coffeecan full of marbles.
(Drop the covers on some hydraulics and you will find them quite difficult to spin, until they leak down.)

Excessive rocker arm endplay may produce a thou or two difference depending upon where it has floated. Pulling the pushrod back and forth when not under tension quickly tells if it is sloppy.
Excessive play in the cam bushings/bearing allows the cam to push from side to side when the pushrods apply resistance. Even with a fresh camchest, it is most proper to alternate adjusting from cylinder to cylinder in order to "center" the cam.
Adjustments must be repeated to assure their accuracy. Pushrods that seem to constantly change are signs of slop in the camchest, or the most dangerous scenario of all, a disintegrating tappet roller.

Finding the "heel" of each cam lobe can be deceiving with aftermarket cams.
After each adjustment, the motor must be turned through four cycles in order to re-check its setting, and often a looser spot can be found. The adjustment must be made at exactly this spot. Stock cams are much more friendly, even though they were never intended for solids.

Now we come to the difficult task of putting the subjective "feel" for adjustment into English.

The pushrod's up-and-down play and slop within it sockets is the lash that we can feel with our fingers. Taking up all lash, but still turning with little resistance is Service Manual spec for iron motors.

But lets add aluminum heads and the need to compensate, as constant lash is more than annoying racket,.. it is destructive to the hardware.
(And remember: The Factory Service Manuals do not address this problem, because the MOCO never produced a solid lifter Panhead.)

When the adjustor has fully taken up the lash, further extending of the adjustor begins to 'preload' upon the valve spring. The tension increases and we feel it as drag when we turn the pushrod between our fingers.
This drag is all we have to inspect by, and once again: any points of bind are an indication of a hardware problem.

So we put some drag on pushrods installed to aluminum heads.
They spin quite freely when warm, but achieve zero lash with any luck at all.

Now add after-market aluminum pushrods, and we must pre-load for expansion drastically.
This can mean putting so much tension on them that a rag must be used to turn them.
But you must still be able to turn the pushrod at the loosest point upon the heel of the cam.
If you lose compression, just loosen them a skosh.
Again, keeping them all equal is wise.
And you may yet still find lash at running temperature!

If you are really worried that valve might be cracked open from tight adjustment, put some air pressure on the sparkplug holes and turn the motor slowly, listening at the carb and exhaust.
With an installed seat pressure for most Pans at around 90 lbs, and much higher for hop-ups, it will take a minimum of 30 pounds of preload to begin to open a valve, if not more.
You must have vise grips for paws if you can turn a pushrod with that tension.

It is easy to see why steel pushrods are preferred by the major performance vendors inspite of their weight.

Looking forward to thoughtful replies,

....Cotten
PS: Off subject, but Flatties close up their valve clearance when they get hot, instead of loosen, as the large mass of metal above expands downward, at much higher temperatures.
Last edited by Cotten on Mon Apr 20, 2009 1:09 am, edited 1 time in total.



51Hog
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Re: Some Observations about Solid Lifter Valve Adjustment

#2

Post by 51Hog » Mon Apr 20, 2009 1:08 am

Very very nice write-up Cotten.
That puts it into perspective that everyone can understand.
Dale

concrete guy
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Re: Some Observations about Solid Lifter Valve Adjustment

#3

Post by concrete guy » Mon Apr 20, 2009 3:11 am

Always enjoy reading your threads Tom. Years of experience are priceless in my book.

I have aluminum pushrods on my solids. I keep a very close ear on the sound of my top end. I tighten them so that I have to clean the pushrod and my fingers to get them to spin. Last year I noticed that I had them a little two tight because it wasn't a one or two kick bike. They were snug like I said but no where near the 30 lbs. that you stated above. It seemed that it was a little harder to start after it was warmed up than when cold so I loosened them up a skosh. Just curious on your thought with that on my 56.

Thanks again.

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Re: Some Observations about Solid Lifter Valve Adjustment

#4

Post by mbskeam » Mon Apr 20, 2009 3:50 am

LOOSE=
ef1f9c41.jpg
nuff said
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51Hog
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Re: Some Observations about Solid Lifter Valve Adjustment

#5

Post by 51Hog » Mon Apr 20, 2009 5:29 am

Mike--
Thanks for posting those pics.
How many miles did it take to do that? Were they really sounding off, or were you just wondering if you were hearing them?
Dale

steinauge
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Re: Some Observations about Solid Lifter Valve Adjustment

#6

Post by steinauge » Mon Apr 20, 2009 11:55 am

Very well done indeed! Note that all iron XLs came with aluminum pushrods.

Cotten
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Re: Some Observations about Solid Lifter Valve Adjustment

#7

Post by Cotten » Mon Apr 20, 2009 1:10 pm

steinauge wrote:Very well done indeed! Note that all iron XLs came with aluminum pushrods.
I rarely encountered any, but then sportsters were always charity cases that rarely made it in my back door. I would have thought they were aftermarket, just like the rest of the crap hung on the machines.
It certainly adds to the "Sportster Disease" epidemiology!

ConcreteGuy noted
"They were snug like I said but no where near the 30 lbs. that you stated above. It seemed that it was a little harder to start after it was warmed up than when cold so I loosened them up a skosh. Just curious on your thought with that on my 56"

Everybody's got a slightly different motor and slightly different fingers, and a 'cold' motor can vary with ambient temperature, etc., etc., so everybody's at their own mercy to get the feel for it.

When the weather changes, you may find yourself adjusting again; Not because the settings changed, but the motor's heat disappation has changed. A change a scenery might be enough, if it includes hills or extra payload that makes the motor work harder.

The variables are endless, and that's why hydraulics are the favorites of those whose need for speed does not exceed their romance with the machine.

....Cotten

VT

Re: Some Observations about Solid Lifter Valve Adjustment

#8

Post by VT » Mon Apr 20, 2009 4:27 pm

Note to all Vol. 1 owners. Our push rod lash adjustment is called "Close Push Rod Adjustment" to distinguish it from the OEM method described in the Knucklehead manual, which could (through an individual's interpretation) allow the lash to be adjusted too loose. Our method is used for aluminum or steel push rod adjustment and should be followed to the letter. I'm here to answer any questions about anything we print.
If there were a correction on any of the procedures we published, it would be listed under "See All Editorial Reviews" on our amazon.com book-sites.
Good road to everyone.

Cotten
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Re: Some Observations about Solid Lifter Valve Adjustment

#9

Post by Cotten » Tue Apr 21, 2009 2:45 am

Well, maybe it doesn't take vise-grips for paws.

The thirty pounds of spring tension I suggested was not to mean it takes 30 ft/lbs of torque to turn the rod. But it was my guess that it would be pretty hard.

Today I stuck a 'solids' slug upright in a press plate, and placed it on a bathroom scale. Then when I used a rocker arm to press a pushrod down upon it, I could feel its drag while I read the pressure applied.

The difference between thirty and forty pounds of pressure isn't much, and it takes a good fifty to drag it down the way I would do aluminum rods.

A fellow could get his own feel for drag at different pressures in this manner, but...
How do we know when the valve will be opened to a dangerous degree? Just the airpressure trick?

Until now, I have successfully assumed that if there was enough compression to start the machine, then warming the motor sensibly would soon take up the pre-load anyway.
Even with cams with healthy overlap.

...Cotten
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concrete guy
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Re: Some Observations about Solid Lifter Valve Adjustment

#10

Post by concrete guy » Tue Apr 21, 2009 3:26 am

I understood your 30 lbs reference the way you intended it to be Tom. Thanks for doing the little experiment, very informative. When I switched over to Sifton solids they wrote that the twisting motion applied to the rod should be fairly tight so I have learned to get the feel of them. I assumed that I had over tightened one or more when I was having problems starting when hot. Like I mentioned I like them to be tight enough that oily fingers will not be able to rotate them but when everything is clean you can spin them. That is the fine line for me.

Thanks again
Scott

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Re: Some Observations about Solid Lifter Valve Adjustment

#11

Post by awander » Tue Apr 21, 2009 4:06 am

Interesting discussion.

BTW, torque is measured in ft-lbs, or feet times pounds, not in ft/lbs or feet per pound.

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Re: Some Observations about Solid Lifter Valve Adjustment

#12

Post by 58flh » Sat Jan 15, 2011 3:02 pm

Whats-up guys----I have been riding my sled now for many years,& I remember going through what i been reading about here! about 25yrs. ago i been running a solid-roller cam type set-up. My first choice was a (dont quote me on this )but I believe a set of Colony aluminum pushrods! & I can remember at least 3 or 5 times bending a rod or just mashing the adj. up the hollow in the pushrod, then blow a hole in the telescope tube!-on a few occasions. It would happen anywhere from 1000 to 2000 miles. What i did was grab some big-block chevy pushrods I had laying around.( there are 2 sizes 3/8&7/16 & they are steel!) I opted for the 7/16 ones,& with a little machine-work,very little, I went & got a set of new Colonys----pulled the adj.& tops out! & sent the rods flying into the river next to me!!! I adapted the chevy pushrods to size & fit the tops&adj. into them. After I took a little step further & pinned the parts with a hardened rollpin,probably didnt need to but this was new to me & didnt take any chances! Atlast never had a problem again----20+yrs now!----since then I been using the 3/8 steel pushrods,to the same effect.( the most important thig is making sure your on the bottom flank of the cam-lobe) then I adj. for no up&down movement---on the exaust valves I give around .003 extra in play lock it down & recheck them all 4 or 5 times) I run straight 60 oil, in the gas I add 3oz. of marvel mystery oil to 5 gallons.) In 15 min. when she is warmed up I have a pleasant sounding symphony of cam,rockers ,springs,pushrods! with no hassels.or breakdowns!-----The weight difference between the 3/8&7/16 pushrods is surprisingly almost a whole weight of a alum. colony rod!----This bike is riden daily ,I can hold between 70&80 mph. down the pike no problem. For me it turned-out to be very good&reliable!--Obviosly Im not dragin it! But if your looking for HORSEPOWER the 7/16s I made for a friend with a shovel-stroker,with good results! hope i answered & helped a few bros out there.----58flh

Cotten
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Re: Some Observations about Solid Lifter Valve Adjustment

#13

Post by Cotten » Sun Jan 16, 2011 4:28 pm

Here's what a little "extra play" on your solids can do:
CAMCRAK.jpg
....Cotten
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58flh
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Re: Some Observations about Solid Lifter Valve Adjustment

#14

Post by 58flh » Sun Sep 23, 2012 1:34 pm

COTTON!---YES that pic. is right on!, This was awhile back when I use to run the ex a smidge loose. What I should of wrote is that with the steel pushrods I ADJ. for no up & down movement on the rod-(cold motor). I do this on all the rods! Just be able to grab it & turn it without any binding & no up & down play!--(steel pushrods only!)---RICHIE,---ALUM. have to be TIGHT! & I dont know of any good quality ALUM. pushrods out there!. Steel is safer & way better for a quiet solid-lifter set-up. 8)

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Re: Some Observations about Solid Lifter Valve Adjustment

#15

Post by George Greer » Sun Sep 23, 2012 3:48 pm

Ok fellas,

That brings to my mind another question if I may.

It this type of damage done only to engines with the solid bushing installed?

George

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