The complete engine assembly was balanced to 0 grams by "Dyno" Don Henderson at Acts II in Statesville, North Carolina. Dyno Don also completed all other machining, and the headwork. Don has experience with the most demanding machining tasks, usually only working on higher-end builds.
Balancing is straightforward: The weights of the pistons, ring set, rods, and bearings are taken, then they are all matched equally in weight to one another. This doesn't mean that the weights of the pistons are matched to the weights of the rings. Basically, each matching component is matched weight to like components, i.e. piston to piston, ring to ring. The process of balancing the crankshaft includes adding or subtracting weight. The crankshaft is centrifugally spun, checked, and either drilled or ground (material removed), or welded (material added) for an even balance.
Overall, free horsepower is easily found in headwork. The castings used in common small-block Chryslers (SBC) are very poor and greatly reduce flow and performance. Our Mopar's heads were flowed at the lift being used, and port modification was decided upon on both the intake and exhaust. The primary work was performed in the bowl, seat, and exhaust port areas. The bowls (areas under the valve seats) are hideous in stock castings and constitute a tremendous power loss. Porting the bowls to 80 percent of the overall valve diameter will provide a marked increase in power. The exhaust deficit (due to overcasting) on stock heads in relation to intake flow is bad, really bad. The heads were ported to achieve a 15-percent variance. This means that our engine will not be hampered by restrictive exhaust ports not being able to flow.
A five-angle valve job is usually standard. A five-angle valve job means there are three angles cut on the valve face and two on the head. Our heads actually received a seven-angle cut: four on the valves, three on the seat. Tim won't give out the angle of the valve cuts because they are proprietary to the power and performance gains he achieves though his work.
New Clevite valve springs proper for this type of roller cam were installed, and high-performance locks and retainers were also used. A replacement roller cam (factory specs) and lifters were used. Again, a Clevite factory-spec camshaft was used because the usage (performance range) intended was so varied. Most of the roller camshaft grinds available vary widely in specifications. The possibility of using too aggressive a cam was clearly present with all cam grinds in relation to the ECU. Basically, a cam affects the ECU by changing the amount of vacuum, reversion, exhaust temp, pulse, etc. An unmodified ECU is slated to operate a "stock" engine and the anticipated set changes that engine sees in its usage. The use of an aggressive cam in some cases is too much for an OEM ECU and it can't cope. The cam would have added more power - probably much more - but the ECU might not have been able to manage the air/fuel ratio, and the engine would consequently run too lean or too rich.
When assembling an engine, it is important to be clear on one thing: correctness. This means getting your tolerances perfect. Do not assume anything or that "close" is OK. Do it right. Proper tolerances are the difference between a 100,000-mile engine and a 200,000-mile-or-beyond engine. Small-block Chrysler engines can be tricky. Check and then double-check again!
Some builders make the common mistake of assuming all is perfect and ready to go right out of the box or directly from the machine shop. Other problems arise when parts are cleaned improperly (this goes for new parts too). Do not forget to double-check all tolerances, fitment, gaps, and endplay. Thinking you can just bolt parts together can lead to disaster.
Trying to cut corners to save a buck or two may lead to more trouble than it's worth in savings. This is especially true if you are concerned about engine longevity, performance, and dependability. Short cuts and inferior parts usually leave an engine builder wishing he had gone the extra mile literally.