What is tappet clearance?

Question

it is related to internal combustion engines.it is provided during their manufacturing.

Answer 1

Well, that term usually applies to engines with mechanical valve lifters (tappets) as opposed to more modern hydraulic lifters (which have zero lash). When setting clearance on mech. lifters you are adjusting the clearance or lash between the valve stems and the rocker arms using a feeler gauge and a socket wrench to tighten or loosen the rocker mounting nut. Typically on an old muscle car engine (350 cu. in. / 360 hp Chevy) intake is set to .024" and exhaust is set to .030", hope that helps.

Answer 2

there is tapper clearance in our syllabus which is given to do tapper on part after moulding or other process

Answer 3

"Tappet Clearance" is the gap between the poppet valve actuator

and the valve stem or cap.

As tested and adjusted, it generally represents the total mechanical gaps

in the entire valve actuator system.

Since the engine parts expand at operating temperature this 'clearance'

is necessary to keep the closed valves on their seats when the engine

is running.

Answer 4

Tappet clearance is a space between the top of the valve stem and the rocker arm.  Its purpose is to allow for some mechanical expansion and lenghtening of the valve stem and push rods as the engine warms up.  This clearance is also called valve lash.  

If insufficient valve lash is set when the engine is cold the valves will not properly close when the engine warms up. If too much lash is provided (additional clearance) then even after the engine warms up there will be some clearance which will result in lost motion.  Lost motion mean that as the cam tryes to open the valve the push rod and rocker arm moves to first take up the clearance before touching the valve to open the valve. The result is late opening of the valve.

Excess lash can beheard in an idling engine as a series of ticking sounds that sould disappear as the engine warms up.  Over time mechanical wear causes an increase in lash usually with the symptomatic ticking sound in the engine (one or more valves can produce the sound). The fix was to remove the valve cover and mechanically adjust the lash with an adjustment s***w on the rocker arm.

Modern engines now operate with zero lash through the use of hydraulic lifters. Lifters use engine oil pressure to automatically remove the mechanical clearance of the valve operating components.   It is possible for dirt in engine oil to foul the tight clearances in a hydraulic lifter and the lash will not be taken out while the engine is running resulting in the ticking noise. The hydraulic lash adjuster would then need to be replaced

Answer 5

The valves open when the tappet 'taps" on the top of the valve and forces it downward, this creating an opening for the gases to come in and out of the cylinder.  Timing has to be perfect.   There is a time associated with the opening and closing of the valves, and the tappet clearance determines that the valves do their thing at just the right time.  If the clearance is too much the valve will open late, and too close it will open too soon.

Answer 6

It's the clearance between the 'Rocker Arm' and the top of the valve 'Push Rod'.