Valvetrain test Flashcards
All of the following are timing components EXCEPT _____.
lifter
An engine has excessive valve guide wear Technician A says to ream the guide and install a new valve with an oversize stem.
Technician B says to knurl the valve stem and reinstall it into the guide. Who is correct?
Technician A
Cylinder heads are being discussed. Technician A says porting is when the size of a passageway is altered. Technician B says polishing smoothes the surface of the port. Who is right?
Both technicians
Cylinder heads should be checked in five planes for warpage, distortion, bend and twist. What tool or tools should be used to check these issues?
Straight edge and a feeler gauge
If your engine has a rocker arm ratio of 1.5:1 and the camshaft lobe pushes up on the rocker arm .400” at the pushrod side, how far would the valve be pushed off of its seat?
.600
Modern day engines can have _____ valves per cylinder.
two
three
four
all of the above
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
Technician A says aluminum heads can be checked for cracks with a process known as magnafluxing. Technician B says a red dye penetrant can be used to check for cracks on cast iron heads. Which technician is correct?
Technician B
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
Technician A says cross-flow heads improve engine breathing. Technician B says cross-flow heads inhibit engine breathing. Who is correct?
Technician A
Technician A says if an OHC camshaft does not turn easily, the head may need straightening.
Technician B says that if warpage is out of specification on the cam side of an OHC head, the head can be straightened. Who is correct?
Both A and B
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 springs should be tested for squareness, tension, and height. Technician B says to stack shims under a valve spring until the spring pressure is correct. Who is correct?
Technician A
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 that before a valve guide can be repaired, the valve seat should always be ground. Technician B says the exhaust and intake valves each operate on a separate lobe on the camshaft. Who is correct?
Technician B
Technician A says to grind less than .020 from the tip of the valve stem to avoid grinding through he hardened area.
Technician B says the tip of the valve should be ground approximately twice the amount removed from the seat. Who is correct?
Both A and B
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
The benefit of using roller rockers is:
Reduced wear and friction
To measure valve spring installed height you measure:
From the spring seat to the bottom of the spring retainer.
Turbochargers are driven by _____.
exhaust flow
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
What are the names of the angles used when grinding valve seats?
Top, seat and Throat
An engine with a turbocharger is a normally aspirated engine.
‘False’.
Another term for mechanical lifter is tappet.
True’.
Cam-in-block engines use pushrods to transmit motion from the lifters to the rocker arms.
‘True’
Intake valves are smaller than exhaust valves.
False’
Springs that have been overheated will stretch and be longer.
False’.
The camshaft is the determining factor in how efficiently the engine pumps air.
‘True’.
Two factors of cam lobe profile are called lift and length.
False’.
Valves will contract as they warm up during use.
False