Cylinder Heads

An internal combustion engine’s cylinder head is the gateway to horsepower, torque, fuel economy and response. It’s the valves, seats and air flow that are responsible for how well the engine runs. So with this thought in mind, why use used – will fit valves and seats? There isn’t a winner in NASCAR that has a poor valve job.

Getting back to machining, the head must be true and straight. There isn’t any used head that isn’t warped. Milling the head true is very important. The valve seats are the most critical area in terms of air flow, both in air entering the engine and exiting the engine.

The object in the head valve job is to get the valves as far out of the casting as possible without hitting the piston and to make sure all valve protrusions are the same – a three angle valve seat helps air flow and the life of the valves and seats. Some port and polishing is very helpful as per the porous castings from the manufacturer.

Last, but not least, spring pressure: why go through all of this expense and use a $2.00 valve spring over. Just think of how many times it’s been compressed. Without the proper spring tension, it will not close the valves properly. And even in high horsepower engines, the turbo boost will hold the intake valves open longer so the intake spring tension must be increased.

We use the round exhaust port design for the best flowing horsepower. Remember that Chevrolet started the round design in the 60’s for the performance and it only took the diesel industry 30 years to catch on. “Not bad!”

The intake ports should be as big as possible because the bigger the better. The more air to get into the engine, the more power you can make. Yet on the other hand, a fuel injected forced air induction engine (turbocharged driven by exhaust) smaller and rounder is better to develop more turbulence and velocity to spin the turbine (exhaust side of the turbo).

Thinking of the exhaust port theory, flowing better, just watch a toilet flush water or a garden hose squirt water. Depending on which way the water swirls, whether it be the United States or Australia, I still have never seen a square toilet bowl or a square hose.

Our new head casting (the pathway to power, torque, fuel economy and response) has all the warpage milled out to our standardized specs for performance. By porting out the valve bowl pockets, cleaning up the short term radius, and polishing the intake runners, we gain better air flow. Using Stellite valve seats with 5 angles called a “3 angle seat”, Stellite valves cut one half of a degree angle off and all valves set at the same height, the cryogenically treated valve guides give longer wear from heat, along with seals – to stop oil consumption.

Copper Head Gaskets

Whenever cylinder pressure is substantially increased, usually as a result of performance enhancing modification, specifically by forced air induction from street blowers, turbochargers, or higher combustion through nitrous oxide injection, something more is needed than a conventional stock head gasket.

We use copper because of its superior thermal conductivity, to stabilize head and block temperatures. It has a 25% coefficient of elasticity that stretches before a catastrophic failure, thus providing an extra measure of safety before failure.

This Pro-Copper Gasket we use is .060 thick with a tensile strength of 32,000 PSI compared to the stock one of 1,200 PSI. Stainless steel O-rings (wire ring) are required to make the copper system work to highest potential. O-ring receiver grooves must be cut in the cylinder head and the stainless wire must be pressed into the bottom of the head with a 25% protrusion for complete crush.

The head gasket must be re-torqued after initial run in using factory torque specs. This is the style of gaskets that all the big boys use, but they won’t tell you.