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Are your Evo Big Twin, Pan or Shovel’s valves noisy even after the engine is warmed up? If the answer is yes, they’re sending you a signal. That clattering sound is the sound of lost power.

High bleed-down reduces volumetric efficiency, the ratio between actual and theoretical flow of air through your engine’s combustion chambers. That’s what determines how well your engine “breathes,” and in some cases, whether it lives or dies.

A very important fact about volumetric efficiency is found in the difference between solid and hydraulic lifters.

Because they’re air cooled, Harley engines “grow” with increasing temperature. A solid-lifter street-ridden Harleys on pump gas will grow as much as .060" between the camshaft and the rocker shaft at 350-degree head temperature.

Now take that .060" and multiply it by the rocker arm ratio, subtract that figure from the valve lift and duration of the cam specifications and guess what, that solid lifter cam just cost you approximately 18 percent in volumetric efficiency! Not to mention the damage to the valve train components.

Hydraulic lifter bleed down rates are still an unknown factor. However, bleed down rate is controlled by a number of factors such as valve lift and duration of your cam, valve spring pressure, and oil temperature and viscosity.

If your hydraulic lifters are noisy after warm up you can safely say the bleed down rate is costing a lot of horsepower.

After much time and testing and development, FLO Headworks is proud to make available the High Performance Hydraulic Lifter Kit that will fits Harley-Davidson big twins from 1948 on.

This top-quality kit is also compatible with most aftermarket cams and stroker motors. Available clearance will accommodate cams up to .600 lift and valve spring pressure in excess of 400 pounds open.

For 1948 to 1953 models, the case must be drilled for oil passage. The lifter hydraulic unit has been greatly improved with anti-float, anti-pump-up and anti-bleed-down features.

High tech bypass and check systems will maintain totally silent operation in a variety of adverse conditions. Oil pressure requirements start as low as 10 psi and go all the way up to 50 psi. Oil viscosity from 20/50W up to 70W, with air temperatures in excess of 100 degrees. The lifter dimensions have been increased in three critical areas.

The body diameter is .110 thousandths larger. The body length is .195 thousandths longer. The roller diameter is .088 thousandths larger. The lifter blocks are cast with 356 grade aluminum alloy. Hardened for maximum strength and durability. Detailed and polished to give a show clean appearance.

The pushrods are manufactured by FLO Headworks from seamless chrome moly tubing, centerless ground for precision construction. The tips are welded and hardened. The nuts are made of 1018 steel with 5/16 by 32 NEF threads for maximum strength and durability.

FLO Headworks High Performance Hydraulic Lifter Kit comes complete with gaskets, installation instructions and all necessary hardware (not pictured).

Our work and products are guaranteed for one year. For an estimate on your particular application contact us directly by telephone at 805-481-6300 or you can e-mail us.

High Performance Hydraulic Lifter Kit


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© 2000-2014, FLO Headworks. Contact Perry Kime at 805-481-6300 or via e-mail.
FLO Headworks, 1150 Pike Lane, #2, Oceano, CA, 93445.
All rights reserved. All prices subject to change without notice.
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