Jim Smart
December 25, 2006
Contributers: Marvin Mcafee Photos By: Marvin Mcafee

Rocker-Arm Stud Girdles
Power comes in many ways, including making the valvetrain more stable. A rocker-arm stud girdle keeps rocker arms stable at high revs by stopping rocker-stud movement, which means more consistent power. Stud movement happens at high rpm, which upsets valve timing. Inconsistent valve timing steals power.

Deep-Sump Oil Pan
We suggest this for much the same reason we suggest a windage tray or high-volume oil pump. A deep-sump pan from Canton, Moroso, Milodon, and others keeps oil away from the spinning crank. It also keeps the oil supply plentiful when we pin the butterflies.

Port Matching
Mismatched ports will steal you blind when it comes to power. During an engine build or head swap, check out port match. Intake-manifold and cylinder-head port sizing must be identical. We're talking perfect port alignment or you will flush power right down the toilet. Cylinder-head ports that are smaller than intake-manifold ports disturb airflow and cause turbulence. Seamless airflow from manifold to cylinder head improves power. When you take delivery of your manifold, check port match and be prepared to do a little grinding. Get those ports seamless, and be certain the alignment is seamless as well. Ports don't have to be polished, just smooth. Polished ports, especially with carburetion, can sometimes rob power. A slightly rough surface helps keep fuel droplets in suspension with carbureted engines.

Exhaust-Port Matching
Exhaust scavenging is as important as smooth intake flow. Why? Because how hot gasses leave determines how smoothly the next air/fuel charge enters and lights, especially when it comes to valve overlap. Get the exhaust flow cleaned up by port matching exhaust ports and headers. Header tubes should always be larger than exhaust ports for smooth exhaust flow. Clean up exhaust ports and header-flange transitions to smooth up exhaust flow. High points and ragged edges (welds) create hot spots and turbulence.

Increase Valve Size
Larger valves make power two ways-by improving and increasing airflow into and out of the chamber. Valves that are too large can rob power, so make sure they aren't shrouded. Also, take an accounting of what happens to the valve based on camshaft lift and duration. How much shrouding occurs at different lift points?

Attention To Detail During Build
We keep harping about internal friction, but it happens so many ways. Blueprint your valvesprings and retainers in order to reduce friction and build in longevity. Gently file all sharp edges and coat valvesprings with a low-friction coating-the same kind used on pistons. Closely examine retainers, rocker-arm tips, studs, valve stems, tappets, pushrods, timing gears, and so on for ragged edges and imperfections that can create friction. The little things add up to substantial power gains.

Think about every possible friction point inside your engine and ask yourself how it can be reduced. Even a pushrod gently rubbing the cylinder head is a friction point. An oil-pump shaft brushing the block creates friction. Valve stem-to-guide clearances that are too tight mean friction. Piston-to-cylinder wall clearances that are a bit snug consume power and make heat. Side clearances and crankshaft endplay create friction. Distributor drive gear to block clearance is another source. The trick is to get just the right amount of clearance with every aspect of your engine build.

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