This block exhibited some tightness on the #5 main bearings, so while we’re at it, we’re dragging a Sunnen align-hone through the main bores, to insure that all is perfectly straight. With the mains torqued in place (including the block girdle from Z10), there is minimal material removal involved, in fact no material had to be removed from the main caps to affect the cure.

As mentioned above, I’m going to use a crankshaft that has bearing codes that when combined with the block’s codes, will reference bearing thickness that are right in the “middle” of Honda’s bearing chart, so we won’t be using bearings that are too “thick, or thin”. There’s probably no good reason for doing this, but I feel best doing it this way, and when you have as many good Honda (and aftermarket) cranks as we have in inventory, selecting one for bearing fitment is simply the way we do it.

This crank is a B20 unit that has excellent journal finishes from the factory. We will not polish the journals, as this could remove enough material to throw our bearing thickness rational completely out the window…..or worse yet, make the use of Honda bearings impossible.

We’re also going to lighten the crank. On the subject of lightened cranks, let me begin with this….the more power you make, the more mass you have to have in the crankshaft, or harmonics will eat the bottom end up. It’s possible to run cranks that have counterweights you can shave with in lower power engines, such as road racing applications, but this is going to be a near 300Hp combination for my street car, and I’m not planning to be replacing the bearings frequently. We will remove approximately 2 pounds from the crank and then neutral balance it. During the balancing process, we’re also radiusing all the hard edges to reduce drag a bit as the crank is slicing through all the oil raining-down in the crankcase. To reduce rotating mass, I’ll be using one of our Clutch Masters aluminum flywheels to decrease rotating inertia at the largest possible diameter for maximum effectiveness and quick acceleration. The crank pulley I’m using is a new ITR unit that we’ve neutral balanced. This balancer will be replaced shortly with one of the new Fluidamper units that we’re helping them design and test, so the bottom end of this engine should be as vibration-free as we can make it.

Now that the block has been bored, honed, and align-honed, it’s time to make the pistons fit the bores with the .0028” clearance I’m looking for. Since saving the block’s cylinders required additional honing that netted a .0039” clearance, we’re going to build up the diameters of the piston skirts with a unique ceramic coating that also affords extreme lubricity…or lower friction. This process is similar to dry-film lubricants most of you are accustomed to seeing, but the material we’re using is much more wear resistant and can withstand extreme pressures. Its application requires a reasonably complex component preparation process and a lengthy heat curing cycle.

Once applied and cured, we are able to block-sand the skirts (with 800 grit wet cloth) until the correct diameter .120” above the bottom of the skirt tang is obtained to achieve my .0028” clearance objective.

As I stated earlier, the pistons I’m using are some early development strutted pieces and their domes aren’t the latest or greatest, but the pistons are “free” and I’ll make do. The valve reliefs on this set were moved outboard for use with an experimental head, which was milled more than .040”.

After massaging the domes, rounding all the corners and edges, we’re also carefully radiusing the edges of the valve reliefs and the edges of the Roller-Wave reflector slot on the exhaust side of the pistons.

I have individual “dummy” cylinders, which have inside diameters machined to the exact bore sizes of all the pistons we sell. These cylinders are used to duplicate the engines bores when flowing heads on our flow bench and they also serve as tool for CCing pistons. We seal the edges of the piston with red grease and insert it into the cylinder, achieving a leak-tight seal where the ring pack meets the ID of the cylinder. The piston is then pushed down to a depth that will allow the highest part of the dome to be just below the edge of the cylinder. This distance is measured with a depth micrometer for future calculations. A light grease seal is used to seal the Plexiglas plate to the top of the cylinder and fluid from a burette is metered into the area between the piston dome and the Plexiglas plate. If we calculate the volume of the cylinder down to the depth the piston is placed, and then subtract the volume of the fluid we used to fill the space above the piston top, we have the CC displacement of the piston dome. These pistons net 6.59CC’s, which is lower than we’d like, but remember that those relocated valve reliefs I talked about are really costing us valuable positive volume.

Next, we’re going to put the crankshaft in the block, suspended by the two end main caps (using some old bearings). We’ll take one of the rods we plan to use (in this case some standard issue Eagle units which are .137” longer than stock and assemble a piston on it. No piston pin clips are necessary for this “operation”.
The piston/rod combination is placed in #1 cylinder with the crank at exact top dead center. A depth micrometer is then used to measure the distance from the block’s deck surface to the quench pad on the intake side of the piston. This operation is repeated in #4 cylinder and each measurement is recorded.