Tip #006 How to Adjust Valve Lash
Setting valve lash accurately requires that each lifter be on the base circle of the camshaft to ensure it's fully closed when you adjust the rocker arm. You've probably heard of shortcut methods for ensuring that the lobe you want to adjust is center on the base circle, but the most foolproof method is to remember "EO/IC", which stands for Exhaust Opening/Intake Closing. Pull off the valve covers and pick a cylinder to start with. Crank over the engine (preferably with a remote starter button and the spark plugs removed), keeping your eye on the exhaust value. When the exhaust valve just starts to open, stop cranking and adjust the lash on that cylinder's intake valve. Then, crank over the engine again, keeping your eye on the intake valve of the same cylinder. After it's fully open, and the rocker tip is at the bottom of its travel, crank it over slowly until the valve is about 2/3 closed. Stop and adjust the exhaust valve on that cylinder. Repeat on each of the remaining cylinders.
     So how do you get accurate, repeatable lash adjustment on every rocker? Some guys adjust the rocker until the feeler gauge has a slight drag when slid between the tip of the rocker and the valve stem, others prefer the gauge to fit tighter. We've found that proper valve setting should pass the "go/no go" test. That is, for a correct 0.020 inch of lash, a 0.020 inch feeler gauge will slide through, but a 0.021 inch gauge will not.

Tip #005 Breathe Easy
Engines are air pumps. The more air you can squeeze in them, the more power they will put out. There are several ways to get more air into your engine. The most common is with the use of a less restrictive air cleaner such as those made by K&N and Holley Performance.  You also want to get this air from outside of the engine compartment. The cooler and denser the air, the more ponies it will produce. The best thing to do, is to create some sort of "ram air" intake to force the air into your engine from the front of your car.

Tip #004 Rocker Ratio 
Dyno testing has shown that almost any engine will respond favorably to a rocker arm ratio increase. Stock small-blocks Chevys have a 1.5:1 ratio. By bumping that up to a 1.6:1 ratio you can expect a gain of about 10 hp on a stock engine, and more than 20hp on modified engines. Installing bigger ratio rockers is straightforward on most engines, but don't go overboard. Too much ratio is a bad thing so keep your increases within one step higher.

Tip #003 Lower your Thermostat
This tip is so easy.. Engines don't like heat. Especially after you've increased ignition timing to squeeze out that last ounce of power. With more timing engines can detonate. To partially cure detonation install a thermostat that's 20 degrees colder than stock. But remember, try not to keep the engine operating at less than 160 degrees, because contaminates that burn out of the oil at higher temperatures will be left behind and eventually break down the lubricant.

Courtesy of 
1001 High Performance Tech Tips
by Wayne Scraba
©1995 Wayne Scraba

Tip #001 - Valve Flow :
Low Lift valve flow is extremely important to performance, although it often isn't considered. Low lift flow centers upon the valve seat. If it isn't right, then the flow cannot be initiated properly. Close attention must be paid to the angles which lead up to the seat, and the only way to determine what's right for your combination is via a flow bench. What you have to look for is a valve seat that minimizes reversion (backwards flow) on the intake side. Any seat configuration that promotes early outward flow on the exhaust side is also important. In the end, this simply means that high performance valve jobs shouldn't be left up to the amateur. 

Courtesy of 
1001 High Performance Tech Tips
by Wayne Scraba
©1995 Wayne Scraba