TECH-LINE

VALVE TIP & OVERALL LENGTH

The Overall Length shown here allows for dimensions that you might be removing if you measured the spring pads from the valve seat, as the author used to do. In this case, you would add the .050" Margin height, as well as another .020" for the BEVEL edge on the valve's combustion chamber side. The valve MARGIN is best around .050" for the intake, and .080" to .100" for the exhaust valves. IF a LASH CAP is used on your particular assembly, you can allow for that thickness, in lieu of the .300" shown.

Valves are very critical in choosing for more than just performance, they are critical in reference to where and how the rocker arm operates; or more specifically, how you make it fit -- to operate.

We established this standard of valve tip HEIGHTS back in the late 1970's. As we shifted from building Ford engines to more popular Chevrolet engines, we became concerned over the many combinations of necessary valve lengths to adjust for installed valve spring heights. A major concern of all engine builders. VALVE TIP HEIGHT needed to be standardized, and it couldn't go by the adaptive terms .100" long, if rocker designs were needed. Because the heads had too much work done to valve seat locations, angle milling, etc. There was no "standard" where using a "loose" term like .100" long will be the same from one combination to the other. Measuring from the sacred valve SPRING PAD was necessary. Using his Ford background, Jim chose the Ford Valve "TIP" specification of .310", to establish where the keeper grooves would be, and Crane's standard spring retainer. They make two other depths, one shallow, and one deep. But with the .300" valve tip length, the crown of the valve tip sticking up above the retainer is perfect for rocker arm underside clearance. If you prefer to use the shorter .250" valve tip length, then you can deduct .050" from 2.250" (for small block engines), using 2.200", and reduce the big block standard to 2.300" as suggested on the previous page: VALVE TIP HEIGHTS. The views shown below can still be achieved with these small valve TIP lengths, but you may have to be more selective in choosing your RETAINERS.

RETAINERS & VALVE TIPS

TOO SHALLOW

TOO HIGH

PERFECT

LEFT: Shows a valve tip which is TOO SHALLOW using a STANDARD depth retainer with a .250" Chevrolet Valve Tip. The more shallow retainer (center) can solve this, but crowds the keepers and has limited choices in keeper styles for strength. CENTER: Shows a shallow retainer with a .300" tip.

RIGHT: Is a "PERFECT" combination of the STANDARD depth retainer on a .300" valve tip. Here both strength and choices in keeper designs are adequate for various installed spring heights and valve tip rise above the keeper is maintained.

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