Valve Train Flashcards
On carbureted engines, a _____ supercharger system pressurizes the air cleaner above the carburetor or fuel injection system.
blow-through
Two technicians are discussing freewheeling engines. Technician A says that a freewheeling engine is one in which the valves will not contact the pistons if the timing chain or belt breaks. Technician B says that a freewheeling engine is one that does not slow the vehicle down when decelerating. Who is correct?
Technician A only
Technician A says on a flat tappet engine, the lifters do not need to be replaced when the camshaft is replaced. Technician B says when replacing a roller camshaft, the lifters must be replaced. Who is correct?
Neither technician
Technician A says there is no need to lubricate the valve stems upon reassembly. Technician B says intake and exhaust seals are the same materials and shapes. Who is correct?
Neither technician
All of the below are factors in camshaft performance EXCEPT _____.
valve size
Technician A says a mushroomed valve can be driven out with a punch and a hammer. Technician B says the mushroomed tip must be dressed with a file before the valve can be removed. Who is right?
Technician B
An engine has excessive valve guide wear. Technician A says to ream the guide and install a new valve with an oversized stem. Technician B says to knurl the valve stem and reinstall it in the guide. Who is right?
Technician A
Cam-in-block engines use pushrods to transmit motion from the lifters to the rocker arms.
True
A properly working supercharger will increase the density of the air in the cylinder.
True
Technician A says that a gear on the camshaft drives the distributor. Technician B says the exhaust and intake valves each operate on a separate lobe on the camshaft. Who is correct?
Both technicians
Technician A says a fixed geometry turbocharger requires pressure relief because it operates over a wide rpm band. Technician B says a wastegate is commonly used to control the speed of the turbine in automobile engines. Who is correct?
Technician B
Another term for mechanical lifter is tappet.
True’
Technician A says excessive valve lift causes piston-to-valve interference. Technician B says high valve overlap can lead to clearance problems between the valves and pistons. Who is correct?
Technician B
Two technicians are discussing valves. Technician A says that most exhaust valves are smaller then intake valves. Technician B says most intake valves are larger then exhaust valves. Who is correct?
Both Technicians
Technician A says valve overlap occurs at the bottom of the intake stroke. Technician B says valve overlap occurs at the top of the intake stroke. Who is correct?
Technician B
Technician A says that basket-type coil springs are installed with the tighter part of the coil against the head. Technician B says grinding a valve seat will not affect the installed height of the valve spring. Who is correct?
Technician A
Technician A says aluminum heads usually have an aluminum shim beneath the valve spring. Technician B says as the valves are removed from the head, they should be kept in order. Who is correct?
Technician B
What value is determined by multiplying the lobe lift by the rocker arm ratio?
gross valve lift
Turbochargers are driven by _____.
exhaust flow
Removal of 0.020” from OHC surfaces will result in 1° of advance in valve timing.
False’.
The camshaft is the determining factor in how efficiently the engine pumps air.
True’.
All of the following are timing components EXCEPT _____.
lifter
Valve springs are being discussed. Technician A says you should discard a 2” spring that is 1/16” out of square. Technician B says out-of-square springs can cause uneven valve guide wear. Who is correct?
Technician B
Technician A says aluminum heads can be checked for cracks with a process known as magnafluxing. Technician B says a red dye penetrant is used to check for cracks on cast iron heads. Which technician is correct?
Neither technician
All of these are dynamic superchargers EXCEPT _____.
positive displacement
An engine with a turbocharger is a normally aspirated engine.
False’
Two factors of cam lobe profile are called lift and length.
False
Technician A says springs should be tested for squareness, tension, and height. Technician B says to stack VSI shims under a valve spring until the spring pressure is correct. Who is correct?
Technician A
The camshaft is the determining factor in how efficiently the engine pumps air while operating at various speeds.
True
The turbine wheel and shaft assembled with the compressor wheel comprise the ____.
rotor
