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Category : A- Small Block "LA" : Lifters : Flat Tappet
HIGH PERF. HYD. LIFTER VARIABLE DURATION
ASSEMBLED W/ HEAVY DUTY RETAINER & QUICKER, EVEN BLEED DOWN RATES
These lifters are held to a higher quality surface finish and have a corner break on the cam face. We suggest using these lifters in high performance applications as they will produce more low end torque. These 5003 lifters also utilize heavy duty pressed in retainer in place of the wire clip. The faster bleed down will create more vacuum than the standard lifter when used with a performance type camshaft. The even bleed down rates will also produce a smoother running engine, with more vacuum at lower RPMs. With these lifters, you can step up 1 cam size and not lose any low end or vacuum.
Plunger travel in this lifter is 0.146 +/- 0.02
Do not use oil heavier than 10W30.
Racing hydraulic lifters for use with an adjustable valve train.
Note: This lifter is an oil metering type. It can be used in engines that oil through the pushrods. Type of retainer ring may vary from photo. Made in the USA by Hy-lift Johnson.
These lifters are manufactured to have a closely controlled leakdown rate that will give them a slight mechanical sound similar to a mechanical cam with a tight lash. The controlled leakdown rate will cause the lifter to give the camshaft a variable duration rate. This reduces the duration (the size of the cam) at lower RPM and builds it back up as the RPM increases. This feature allows a larger cam to be used on the street without the loss of low end torque associated with OEM style lifters and these lifters are quieter than other "so called" variable duration lifters.
Any tappet adjusted to .000" preload will operate as an "anti-pump up" lifter (We do NOT recommend .000" preload, this is a comparison). However, when using a lifter with a small wire retaining ring such as OEM lifter (shown as #5001), there is a higher probability of the retainer ring failing with this amount of pre-load. Anytime maximum RPM is necessary and a minimum tappet preload or lash is used, racing lifters with heavy duty retaining rings (#5003) are strongly suggested.
If you are converting an OEM roller lifter engine 1987-1991 to a conventional flat tappet camshaft use P/N 5001 or 5003, along with the proper length pushrods. Do not fill or pump up hydraulic lifters before assembly. They may hold the valves open causing difficult starting and/or engine damage.
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