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
