The Balancer Delete

On the F/H-series honda engines the oil pump housing takes up most of the front (belt side) of the block. The actual functional part of the pump is not so big. Maybe the size of a 10oz. steak. However, for many valid design and engineering related purposes the balance shaft system is integrated with the pump housing.

The following excerpt from Wikipedia.com explains the concept of a balance shaft system well.

Balance shafts are most common in inline four-cylinder engines which ... have an inherent second order vibration (vibrating at twice the engine RPM) which cannot be eliminated no matter how well the internal components are balanced... This vibration is generated because the movement of the connecting rods in an even-firing four-cylinder inline engine is not symmetrical throughout the crankshaft rotation; thus during a given period of crankshaft rotation, the descending and ascending pistons are not always completely opposed in their acceleration, giving rise to a net vertical inertial force twice in each revolution whose intensity increases quadratically with RPM...

The problem increases with larger engine displacements, since one way to achieve a larger displacement is with a longer piston stroke, increasing the difference in acceleration or by utilizing a larger bore thereby increasing the mass of the pistons. One can utilize both techniques in order to maximize possible engine displacement. In all cases, the magnitude of the inertial vibration increases. For many years, two liters was viewed as the 'unofficial' displacement limit for a production inline four-cylinder engine with acceptable noise, vibration, and harshness (NVH) characteristics.

The basic concept has a pair of balance shafts rotating in opposite directions at twice the engine speed. Equally sized eccentric weights on these shafts are sized and phased so that the inertial reaction to their counter-rotation cancels out in the horizontal plane, but adds in the vertical plane, giving a net force equal to but 180 degrees out-of-phase with the undesired second-order vibration of the basic engine, thereby canceling it...

By Wikipedia's description the reason for the shafts in inline-four engines over 2 liters is to bring the NVH to acceptable levels. Frankly, I couldn't care less about NVH characteristics. If the price of less complexity, less static weight and more available power is noise, vibration and harshness then I will gladly pay it.

When I remove the shafts there will be open holes in the front of the block/oil pump. Those will need to be patched somehow. There will also be empty bearings in the block which are feed by pressurized oil from the pump. Without the journal of the balance shafts to control the flow, oil pressure would drop and other critical parts of the engine would be starved and eventually seize. That's not so good. To take care of these issues I've ordered and installed Kaizenspeeds balance shaft eliminator kit.  The kit replaces a few hollow dowels in the main caps and block brace with solid ones, plugs the holes where the shafts once protruded the front of the block and replaces the rear shaft reversing gear with an aluminum block off plate.

First things first, the pump needs to come off.

Had a little fun in Photoshop with this one. This is the oil pump with balance shaft pulleys still on. Time to get it off!

I've got the head off and the block on the bench. The pulleys also have been removed along with the oil pan and sump pickup.

Once all of the M6 bolts are off some careful prying with a screwdriver breaks the sealant and the pump can be removed from the block.

 The left balance shaft is retained in the block by the small plate with the two bolts and the right shaft...

...stays with the pump housing. It's held in by the gear at it's end. The two gears in the hosing on the right (in the first image) act to spin the shaft the opposite direction. 

After the gear is removed I held the shaft in a vice and gave a few taps with a mallet to free the shaft from the pump.

Here is the pump. As part of the kit I've pressed in the plugs (highlighted in pink) to cap off the now unused holes left by the shafts. The three yellow circles are holes that feed oil to and drain oil from the reversing gears for the rear shaft. The block off plate from the kit covers the area traced in blue. I've decided it would be better to tap the three holes and use threaded plugs to seal them.

This is the bulk of what's being removed. Altogether it weighs about 10lbs.

The "main bridge/block brace/crank girdle" in the shot above gets these three solid dowels to block oil flow to the now unused bearings. The hole at the upper left is clearly smaller than the supplied plug. I contacted the guys at Kaizenspeed and they were able to make a custom dowel for me. Apparently the F23 is slightly different from the F22s and H22s they made the kit for.