Once the head was finished being reworked by Portflow, Tom hand-lapped each valve per NPD's request. A gray ring should form 360 degrees around the valve and valve seat. Although head specialists like Portflow perform vacuum testing, not all do. Vacuum testing on its own is great, but hand-lapping promotes a sense of break in between the valve and the seat, in conjunction to creating a contact patch that's visible to the builder. NPD's belief is that the responsibility of final assembly falls on the shoulders of the engine builder and not the machine shop. These details should be examined by the builder prior to assembly. Each valvespring is then checked to ensure that they're equal and up to manufacturer specifications. In this case, we're using Supertech dual valvesprings with a seat pressure of 225 pounds and an 11.8 lift.

Final assembly was performed using Supertech titanium retainers, buckets, and shims. Instead of the factory-style outer shim, Supertech switches to an inner shim-type bucket. This frees up about 32 percent in weight from the bucket assembly and helps in reliability during high rpm operation. Although there's a port on the front water neck, which can be connected to an air separator tank, we opted to incorporate Auto Staff's water bypass block. This provides an additional source to remove any trapped cavitations in the cooling system.

While this much work may seem a bit excessive, this is the standard amount of effort and consideration that should be taken into building a motor of this caliber. These techniques can be applied to any high-performance motor build. Stay tuned for the next installment as we take a visit to the machine shop to have our KA24DE block bored and honed.

SOURCE
AMS Performance Portflow
Auto Staff
Distributed by AP Boss USA
Supertech Performance
NPD
800-521-6104
www.nationalpartsdepot.com