Adjusting Pushrods

Different push rods require different adjustments as explained by Donnie Smith.

Also see the lower half of this post for the post by TQ.

One reason you are getting different explanations is that there is more than one right way. The second reason is that Harley mechanics and wannabe wrenches alike are always trying to reinvent the wheel. This is one of the many idiosyncrasies that define the contradictory nature of the Harley rider in Harleydom. "There must be a better way", they reason. Well……sometimes there is and sometimes there isn't. When there isn't a better way they are not deterred in their quest. On they go, using half truths and rationalizations to fuel their rebellious needs. Take oil for example. Airplanes must use the very best products. Right? Right! Therefore the oil they use must be better than what the automotive industry has developed for land based vehicles. Right? Wrong! A top automotive/motorcycle oil, (which are the same but we won't go into that scam of scams now), is unsuitable and even potentially downright dangerous in an airplane. And yes, you got it, an airplane oil is especially unsuitable for your Harley. Enough of that, Magic, let's explore some of the right ways to adjust pushrods. You didn't mention the year and model of your bike which is ok with me since I can ramble on even more than normal.

Types of Pushrod/lifter setups

Some Panheads used a solid lifter with a hydraulic pushrod. I haven't seen one of these setups, which is still functional anyways, for many years now. We won't go into these ones since 99% of Harley riders will never see these anyway. Early Big Twins and all Ironhead Sportsters used a solid lifter assembly with an adjuster built in. These were combined with fixed length pushrods. Shovels use a hydraulic lifter with an adjustable pushrod. Evo Big Twins and XL's and Twin Cam 88's use a non-adjustable system with fixed length, location color coded pushrods and automotive type non-adjustable hydraulic lifter/tappets. The aftermarket expands on all these types. They provide very necessary adjustable pushrods to replace the fixed length Evo and Twin Cam 88 ones. Another example is the Colony spring loaded solid lifter kits for the Shovels. There are little springs that supposedly take up play when the engine heats up and expands. Many riders like these kits since they allow for a little sloppier, (I didn't say correct), adjustment. The same riders dislike the S&S solids since an eighth turn preciseness is required for quiet but very effective operation.

Always do these steps:

Rule 1

The engine must be COLD during adjustment….not hot, not warm, not cool…it must be cold. Why? The metal expands when the engine is hot. The barrels, heads and rockers grow taller when hot and contract when cold. If a pushrod/lifter is adjusted when the engine is hot, the valve may be forced open as the engine cools and contracts. A valve that is opened at the wrong time will cause a loss of compression at the very least. At most the extended valve will hit the ascending piston and bend necessitating a rebuild. This can also happen if the lifters are adjusted on a high spot of the cam lobe. More on this in a bit. The Pros can tweak a lifter adjustment while the engine is hot. They listen to the tappet noise when the engine is running and determine which of the four is making the noise. They can tell by the noise on how much to turn down or up the adjustment. Leave these smooth moves to the Aces as they are also capable of rebuilding your top end if they screw up.

Rule 2

Take nothing for granted in mechanics If unfamiliar with the lifter setup that is about to be adjusted always read THAT SPECIFIC manufacturers instructions. Sound stupid? Not really when you consider that the threads per inch on the adjusters vary from manufacturer to manufacturer. One source may say turn the adjuster down 5 full turns. Well 3 full turns is more when there is less threads per inch and it is less when there is more threads per inch.

Rule 3

Always ensure the lifter/tappet/pushrod is at its lowest point before adjusting or else all kinds of bad things can happen. I'll expand on this later.

Rule 4

If there are two lengths for the 4 pushrods, the longer ones go into the exhaust portions of the valve train which are at the extreme front and the extreme rear. If there are three lengths, put the longest in the front exhaust, the second longest in the rear exhaust and the two shortest ones in the middle on the intakes.

Rule 5

Adjusting the pushrods too loosely will result in too much clearance and excessive valve train noise. Do it too tightly and the valve will be held open causing a loss of compression and power at the least. Tighter still and an ascending piston will bend the open valve.

Rule 6:

Practice makes perfect.

Pre-adjustment Procedure

On all models except the 1990-99 Sportster which has one piece pushrod tunnels, push the spring retainer down. If you have paws the strength of Godzilla you can do this with your fingers. For the rest of us, there are various techniques. The one I use is with a slotted or flat-sided screwdriver. I wedge the slot, horizontally between a couple of head fins while the screwdriver shaft lays on top of the spring retainer. The leverage provided allows for the retainer to compress easily. This can be done with one hand. With the other use another slotted screwdriver or a set of needlenose pliers and remove the spring keeper.Now the lower cover can be easily pushed by hand over the upper cover exposing the adjuster mechanism.

Oil Seals

On 1978 and earlier models, a set of 12 cork washers are used to seal the various component pushrod tunnels at the top where they mate with the head, at the bottom where they rest against the tappet guide and in the middle underneath the spring retainer. Circa 1979 and later models use rubber o-rings. The corks and o-rings are not interchangeable since the mating pushrod tunnels are designed for either or but not both oil sealing methods. It is prudent to replace these seals every time an adjustment is made. I've learned to do this even if the seals look ok since doing the same job twice is a drag. This will necessitate removing the pushrods totally. This is no big deal. Undo the locking nut and turn the tappet adjuster down or the pushrod adjuster up as the case may be. Rotate the engine until the tappet, (lifter), is at its lowest point. At this point the pushrod can be removed.

Rotating the engine:

Remove the spark plugs. Why? There will not be any engine compression building up to make this easy job difficult. If the engine is out of the bike or the clutch is totally disengaged with the outer primary removed, the engine sprocket, which is attached to the engine shaft at the front of the primary chain case, will be free to move. There is a special tool for this rotation procedure but it is not required for the hobby mechanic. Put on some gloves and turn the sprocket until the tappet is at its lowest point. However, in most cases, the bike will be in your garage or on the side of the road. Put the bike in the highest gear possible. Why? The engine will rotate easier than if in a lower gear and it will rotate slower to enable a more precise determination of the lowest point of the lifter as it rotates over the cam lobe. A friend can roll the bike back or forward while you observe the lifter going up or down on the cam lobe. The rear wheel can be raised off the ground via a bike lift or put on a crate in order to manually rotate the rear wheel back and forth to obtain the lowest point on the lifter/cam lobe. As an exercise, rotate the rear wheel in first gear by hand while it is on a lift or a crate. Now put the bike in 4th gear and try it again. This will demonstrate the reason for doing this procedure in a higher gear.

How to tell if the Tappet is at its lowest point.

There is not one precise location that is the lowest point so it is easier to find as it is many degrees of the cam heel. Of course, I didn't know this simple little fact when I started out so I methodically used to roll the bike back and forth looking for the precise spot wasting time and causing much anxiety. After all, the penalty can be a bent valve if a lifter/tappet is adjusted on a high spot of the cam lobe. If you look at the lobe of a cam, which you can ask to see in the shop you patronize, you will notice quite a distance where the lifter will remain at its lowest position. Why? The corresponding intake valve will remain closed while the exhaust valve is open to allow the spent gases to exit on the exhaust stroke. Or, the exhaust valve will be closed on the intake stroke while virgin air/gas is sucked into the cylinder. Or both valves will be closed on the compression and the power strokes. So, what are some techniques for arriving at the cam lobes low point? One way is to put the piston at TDC, (top dead center), on its compression stroke. Huh? I'll explain three ways to figure this out. With spark plugs removed put your thumb firmly over the spark plug hole of the cylinder for the pushrod that needs adjusting. Have a friend rotate the rear tire or gently kick the bike over if it has a kicker. The piston will build up pressure on your thumb as it rises on the compression stroke. When feeling this pressure, look into the spark plug hole with a flashlight and the TDC of the piston can easily be determined. A second way. Remove the timing plug on the left center side of the engine at the base of the cylinders, (barrels). With the piston at TDC, the timing mark will be aligned in the center of the timing plug hole. The front cylinder is indicated on most engines by a straight vertical line. A round dot near the top of the hole on some year engines also indicates TDC. The rear has a rectangular horizontal mark or a single dot near the bottom of the hole. Harley has changed these marks over the years so it is wise, as usual, to check a manual whether it be Harley or a variety of others like the user friendly Clymer. Or you can physically watch the lifter go up and down while rotating the engine. The first two ways allow adjustment of both lifters in the same cylinder side once TDC on the compression stroke has been determined. In these two cases the lifters on the opposite cylinder will be at their highest point.Every Harley wrench has a favorite way of doing this. Remember that there can be more than one right way.

Adjusting Pushrods

Shovel Hydraulics:

This system has the adjuster and locking nut on the bottom of the pushrod. It is used from 1966 to 1984 on FL and FLH's. There are various ways of doing these and I'll relate two. Unlock the locking nut. Two 7/16" open-end wrenches are required but 3 make it easier. I grind down the faces of these wrenches to provide more room in a tight spot. There is a flat on the pushrod that is narrow for stabilizing the rod especially when locking the lock nut. This flat requires a skinny wrench. Hold the pushrod stable with one wrench while slowly turning down the adjuster screw until the hydraulic lifter is fully compressed. No brute force here. This is a job for a sensitive person of the Nineties. Once compressed, turn up the adjuster 1 1/2 turns. Now lock the locking nut. I use 3 wrenches here to ensure the adjuster does not turn while snugging up the lock nut to the base of the pushrod body. Torque is between 6 and 11 ft-lbs. No, a torque wrench will not fit in here! You'll have to practice tightening this size nut on a bolt and then checking it with a torque wrench until you get the "feel". Harley has a tool called the Pushrod Adjustment Gauge, (part #94438-79), that is a glorified bent up clothes hanger. You place the gauge on the lifter. Adjust until the top of the lifter is even with the top of the gauge. To me, this is a ballpark adjustment and I have never used this tool since I feel that if you need the gauge maybe you shouldn't be foolin' around in there in the first place.

Ironhead XL's, Knuckles, early Pans and S&S solids in a Shovel:

These Harley systems have a non-adjustable pushrod that fits into a solid lifter incorporated into the tappet body. The S&S solid lifter adjusting mechanism fits snugly into the later style Shovel tappet body. Solid means that there is no cushioning or expansionary device to take up extra room created when the top end expands with heat. Therefore the adjustment becomes a compromise one. Here is what the HD manual says to do. Once adjusted, "the pushrod should have a slight amount of play or shake and must freely turn completely around without trace of binding, when rotated by the fingertips." I agree with this particularly on the Knuckles and to a lesser extent on the Pans since the valve springs tend to be weaker especially if they are original. On the Ironhead XL's and with the Shovel S&S, I like to have the adjustment tighter where I can barely rotate the pushrod with my bare oil free fingers. This is difficult to get this exact adjustment since it is very precise.

Evo Big Twin + XL + Twin Cam 88

All three of these engines have fixed length pushrods with NO lifter adjustment. Pushrods are location color coded for mechanics that prefer not to think. Stock fixed length pushrods require the removal of gas tank(s) and all 3 Evo wafers for installation. The "Fathead" has two wafers but only the top has to be removed and the rocker arm supports have to be loosened and/or rocker arm shafts removed. This is a lot of time consuming work requiring expensive gasket replacement. The aftermarket supplies adjustable pushrods in two main styles to allow for more precise adjustment. They are also made out of superior materials and are sometimes lighter. However, the real reason I use these kits is to save time and money.

Tip: Use bolt cutters to cut stock pushrods in half for easy fast removal. Don't despair. They only cost a couple of bucks and are useless. If you ever need any for free I have hundreds on hand just taking up space.

The more inexpensive of the two, (quality is still superior to stock), requires that the timing cover come off and the cam pulled. This allows the hydraulics to slide down which allows the adjustable pushrods to fit in. There are a variety of ways to install them but this is the way we do it. The labor and gaskets saved easily makes up for their cost. The more expensive ones are colloquially referred to as "Timesavers" or "EZ-install". Even less part removal is required since the pushrods can be shortened more than the normal adjustable ones. 1990-1999 Sportsters have one piece pushrod tunnels, which necessitate wafer removal. For stock motors, I see no reason to use the adjustables in this particular application. On late model hi-performance XL motors we will substitute older style removable pushrod tunnels in order to use the adjustable pushrods for more precise and frequent tweaking. I think Andrews explains the theory behind adjusting these rods best. "For hydraulic lifters to function correctly, the engine oiling system must operate with at least 10 to 15 psi oil pressure…..in this case more oil pressure will not be better. Hydraulic lifter units…..can move down approximately .200 inches. This downward travel is called the adjustment range. In other words, the adjustment length starts at 0 and can be as much as .200 inches. A correctly set adjustment places the hydraulic unit in the middle of the .200 travel range."

Andrews V2 BT + XL + TW 88 1984-1999 adjustable pushrods:

Lengthen the adjuster screw by hand until it makes tight contact with the seat in the hydraulic lifter. Extend it further by 3 to 4 full turns. I'll let Andrews explain and you can decide on your own adjustment. "Andrews adjusters are manufactured with (5/16 x 32) threads so 3 turns will create an adjusted length of .093 inches. (3 x 1/32 = .093 inches). Each turn extends the adjustment by .032 inches. As long as the hydraulic unit and pushrod seat can move up and down and not touch the top retaining ring or "bottom out" during operation, the pushrod length has been correctly set and the lifters will function normally." Andrews advises to adjust their TW "88" pushrods 3.5 to 4 full turns.

S&S:

The same procedure as above but turn down the adjusting screw 4 to 4 1/2 turns once free play has been eliminated. Remember differing threads per inch require a different number of turns.

Crane:

Same thing here but 3 turns is the key here.











More info here on the JIMS site.

http://www.jimsusa.com/pdf/2411.pdf


Posted by TQ...

Adjusting pushrod:

With the pushrods removed from the engine, rotate the rear wheel watching the lifters rise and fall to determine when the piston is at TDC on the compression stroke.

With piston at TDC on compression stroke (see above), install and thread out the adjustable end until it JUST touching lifter socket. Make sure top end of PR is nicely in rocker arm socket. Should be able to rotate the PR easily, but no vertical movement.

Mark the flat on the rod facing you and then I ROTATE the TOP section of the PR while holding the "bolt" end from turning (but this is the end that is actually extending). This is just my personal preference, and I think that either end can be adjusted as long as you can keep track easily how many turns have been made (that is why I do it the way I do).

Once the correct number of turns have been made, lock the jam nut, and move to the other PR. Adust it the same way.

When both are adjusted, go take a break for 15-20 min. When you get back, you should be able to rotate the PRs with very little effort. If not, go take another break.

When the PRs rotate easily, button up the PR covers.

Rotate the rear wheel until the other piston is at TDC on its compression stroke, and similarly adjust those two PRs. When all done, then I follow the rest of the procedure I descibed previously.

Calculating the Adjustment

The PRs should identify the tpi for the adjuster end. Let's call that X. So each complete turn of the adjuster is 1/X inches increase (or decrease!) in the length of the PR. So as an example:

24 tpi = 1/24th inch per turn or .0417"/turn
28 tpi = 1/28th inch per turn or .0357"/turn
32 tpi = 1/32nd inch per turn or .0313"/turn

Now as a general rule, to figure out the number of turns you would divide half the lifter piston travel by the number of inch/turn to give you number of turns.

Another method is to multiply the tpi times half the lifter piston travel. In the case of the "B" lifters, since this is a nice figure of 1/8" or .125", we multiply that times tpi to give you this:

24 tpi = 3 turns
28 tpi = 3 1/2 turns
32 tpi = 4 turns

This last method is the easiest. So if you want a different adjustment besides half the lifter piston travel, it is exactly the same process; that measurement times the tpi = number of turns.

Since the adjustable PRs will have hexagonal nuts on the end of the rod part, each flat is 1/6th of the movement noted above or the following fraction of turns per flat:

1 flat = 1/6th = 0.167 turns
2 flats = 1/3rd = 0.333 turns
3 flats = 1/2 = 0.500 turns
4 flats = 2/3rd = 0.667 turns
5 flats = 5/6th = 0.833 turns

So if I wanted to adjust my 24 tpi PRs to 0.140" out, it is:

24 x 0.140 = 3.36 turns

3.36 turns is approximately 3 turns and two flats!!

So, that was all long winded, but I hope it makes sense.