cylinder heads and valves. cylinder heads purpose – regulates the air/fuel in/out of the engine...
TRANSCRIPT
![Page 1: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/1.jpg)
Cylinder Heads and Valves
![Page 2: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/2.jpg)
Cylinder Heads
Purpose – regulates the air/fuel in/out of the engine
Construction Cast Iron Cast Aluminum
Overhead valve heads incorporate: Valves @ related components Coolant passages Valve operation mechanism(s)
![Page 3: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/3.jpg)
Cylinder Heads Overhead camshaft heads will also incorporate: Camshaft(s) Rocker arms or followers
![Page 4: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/4.jpg)
Hemispherical Cylinder Heads
Hemi – a Chrysler term for a symmetrical cylinder design.
Typically valves would be positioned directly opposite in the head with (ideally) a spark-plug positioned between them. Modern designs my incorporate two spark-
plugs. NOT exclusive to Chrysler!
![Page 5: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/5.jpg)
![Page 6: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/6.jpg)
Hemi Head
![Page 7: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/7.jpg)
Cylinder Heads
Cross flow head design – the practice of placing the intake port and the exhaust port on opposite sides of the cylinder head.
![Page 8: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/8.jpg)
Traditional Arrangement
Traditionally, combustion chambers would have one exhaust valve and one intake valve.
![Page 9: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/9.jpg)
Four valves per cylinder – two exhaust and two intake valves. Pentroof
design – each pair of valves are inline
Multiple Valves
![Page 10: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/10.jpg)
Intake - Exhaust Ports
The passageways in the cylinder head that lead to/from the combustion area.
Intake: Larger ports = more airflow Smaller ports = better
velocity for low RPM operation
Longer ports = better atomization on carb and TBI
Shorter ports = denser A/F charge
![Page 11: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/11.jpg)
Gasket Matching
•Using an intake gasket as a template to “port” the heads
![Page 12: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/12.jpg)
Coolant Passages
Coolant travels through the cylinder head from the engine block.
Cylinder head gaskets may be designed to restrict coolant flow rate. Often a source for
corrosion and leakage.
![Page 13: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/13.jpg)
Blown Head Gasket
![Page 14: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/14.jpg)
Cylinder Head Removal
All aluminum cylinder heads should be removed with a reverse torque procedure.
![Page 15: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/15.jpg)
Cylinder Head Resurfacing
Heads should be checked in five places for warpage, distortion, bends or twists.
Check manufacturers specifications, maximum tolerances usually around .004”.
![Page 16: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/16.jpg)
Valve Guides
The “bore” in the cylinder head that supports and controls lateral valve movement. Often integral on
cast iron heads Always an insert
on aluminum heads
![Page 17: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/17.jpg)
Valve Guides
Steel insert on aluminum heads
![Page 18: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/18.jpg)
Valve Stem To Guide Clearance
Always check manufacturers specs Intake valve will typically be .001
to .003” Exhaust valve will typically be .002 to
.004” The exhaust valve stem clearance
will generally be greater due to the higher operating temperatures.
![Page 19: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/19.jpg)
Valve Guide Wear
Guides are checked in 3 locations With a small-hole
gauge then measured with a micrometer
Or checked with a small bore gauge
![Page 20: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/20.jpg)
Valve Stem Wear
Measured with a micrometer at three separate locations.
![Page 21: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/21.jpg)
Valve Stem To Guide Clearance Correction
Oversized Valve Stems – the guide is reamed to accept a larger stem. Must use a valve
with an oversized stem.
Reduced flow rate
![Page 22: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/22.jpg)
Valve Stem To Guide Clearance Correction
Valve guide Knurling – a tool is driven into the guide that displaces metal thus reducing the inside diameter of the guide. (p. 340-341) The guide is then reamed to attain proper
clearance Not recommended for clearances +.006
![Page 23: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/23.jpg)
Valve Stem To Guide Clearance Correction
Valve guide replacement – (insert) the old guide is driven out and a replacement guide is driven in.
The guide may require reaming to achieve proper stem to guide clearance.
![Page 24: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/24.jpg)
Valve Guide Inserts – (integral) the old guide is drilled oversized and inserts are installed. Pressed fit May be steel or
bronze
Valve Stem To Guide Clearance Correction
![Page 25: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/25.jpg)
Valve & Seat Service
![Page 26: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/26.jpg)
Intake & Exhaust Valves
Automotive valves are of a poppet valve design.
![Page 27: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/27.jpg)
Valve Materials
Stainless steel May be aluminized to
prevent corrosion Aluminum
Hardened valve tips and faces
Stellite (nickle, chromium and tungsten) valve tips and faces
Stellite is non-magnetic
![Page 28: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/28.jpg)
Valve Materials Sodium-filled – a hollow
stem filled with a metallic sodium that turns to liquid when hot (heat dissipation).
Exhaust valves are largely comprised of a chromium material (anti-oxidant) with nickel, manganese and nitrogen added. May be heat-treated May be of a two-piece
design
![Page 29: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/29.jpg)
Intake & Exhaust Valves
Valves are held into place by a retainer and keeper.
Aluminum heads will have a separate spring seat (iron heads will have integral seats)
![Page 30: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/30.jpg)
Valve Seats
Integral seats – cast iron heads – induction-hardened to prevent wear
Valve seat inserts – typically aluminum heads – hardened seats are pressed into the heads
![Page 31: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/31.jpg)
Valve Inspection
Valve tips should not be mushroomed
Most valve damage is due to excessive heat or is debris “forged”.
Replace any valve that appears Burnt Cracked Stressed Necked
![Page 32: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/32.jpg)
Valve Springs
A spring “winds-up” as it is compressed – this causes the valve to rotate.
May have inside dampers to control vibration.
Springs are camshaft specific. Squareness (+ (-) .060) Spring free height (+ (-) .060) Compressed force (+ (-) 10%)
Valve open height Valve closed height
![Page 33: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/33.jpg)
Valve Spring Tester
![Page 34: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/34.jpg)
Valve Seat Reconditioning
The angle of the valve seat is reconditioned.
Often 3 stage (triple-angle) to promote flow and overhang. May be done with “seat
stones” May also be done with a
SERDI type set-up where the 3 angles are cut with one cutting tip.
![Page 35: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/35.jpg)
Valve Reconditioning
The stem is lightly chamfered to insure proper fit in the valve grinder.
The face of the valve is reground using a valve grinder. (45 or 30 degrees typical).
Interference angle – the practice of grinding the face 1degree less than the seat angle.
The valve must retain its “margin” area.
the stem should be ground ½ the value that the face was ground with nonadjustable rockers.
![Page 36: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/36.jpg)
Valve Lapping
The use of valve compound and a suction cup stick to establish a pattern
May be done to “freshen” the seat and face areas
![Page 37: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/37.jpg)
Valve Lapping
The use of valve compound and a suction cup stick to establish a pattern
May be done to “freshen” the seat and face areas
Also used to check the contact pattern while cutting valve seats
All compound must be removed prior to
service
![Page 38: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/38.jpg)
Valve Seals Valve Seals are
designed to allow sufficient lubrication of the valve stem/guide and also control oil consumption.
Umbrella seals – hold tightly onto the valve stem
Positive valve stem seals – hold tightly onto the guide
O-rings – controls oil between the spring and retainer
![Page 39: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/39.jpg)
Checking Installed Height
If a valve seat and face are cut the valve will sit lower in the head.
The result is that the stem will sit higher on the top of the head.
This will cause the springs to have improper tension.
Installed height is measured and shims are added under the spring to compensate.
![Page 40: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/40.jpg)
Camshafts
![Page 41: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/41.jpg)
CamshaftThe camshaft rotates ½ times
the crankshaft – or – once per four-cycle stroke.
The camshaft may operate the: Valve train Mechanical fuel pump Oil pump Distributor
![Page 42: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/42.jpg)
Camshaft Major function - operate the valve
train. The lobes on the cam open the
valves against the pressure of the valve springs.
Bearing journal can be internally or externally lubricated (oiled).
![Page 43: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/43.jpg)
When installing externally oiled cam bearings it is essential that the holes in the bearings lineup with the oil passages in the block
![Page 44: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/44.jpg)
Camshaft
Pushrod engines have the cam located in the block.
•Cam is supported by the block and the cam bearings.
![Page 45: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/45.jpg)
•Cam may or may not be held in place by a thrust plate.•Most roller camshafts are held in by a thrust plate.
Camshaft
![Page 46: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/46.jpg)
Overhead Camshafts
Overhead camshafts are either belt or chain driven and are located in the cylinder heads.
![Page 47: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/47.jpg)
Overhead Camshafts Will use one of the following:
Cam followers Rocker arms
May have a one piece lifter – rocker design
A bucket design
![Page 48: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/48.jpg)
Camshaft Operation
![Page 49: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/49.jpg)
Bucket Design
![Page 50: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/50.jpg)
Camshaft Followers
![Page 51: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/51.jpg)
Rocker Arms
![Page 52: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/52.jpg)
Design
A cam casting will include Lobes Bearing
journals Drive flange
(gear)
![Page 53: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/53.jpg)
Design
A cam casting may include Oil pump drive
gear(s) Fuel pump
eccentric (mechanical fuel pump)
![Page 54: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/54.jpg)
The fuel pump plunger rides on the camshaft eccentric.
![Page 55: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/55.jpg)
Classification Camshafts are of one of four types:
Hydraulic flat-tappet Hydraulic roller Solid flat-tappet Solid roller
This designation is actually determined by the lifter design.
![Page 56: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/56.jpg)
Hydraulic flat-tappet
The lifter is “spring” and oil loaded to allow for compensation.
Traditional O.E. style (1950’s – mid 90’s)
Used with flat or convex-faced lifters Generally cast iron or hardened steel Requires a “break-in” period to
establish a wear pattern
![Page 57: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/57.jpg)
Cutaway view of a hydraulic lifter. TECH
TIP
![Page 58: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/58.jpg)
Flat tappet Lifters
![Page 59: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/59.jpg)
Hydraulic flat-tappet
Most cams are coated at the factory with manganese phosphate . This gives the cam a dull black appearance. This coating is to absorb and hold oil during the “break-in period”.
![Page 60: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/60.jpg)
Hydraulic flat-tappet Most late model designs use a convex bottom (.002”)
to encourage lifter rotation. This rotation helps reduce lifter and (or) bore
wear. The Cam lobe will also be slightly tapered (.0007”
- .002”). This provides for a wider contact pattern.
![Page 61: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/61.jpg)
Hydraulic flat-tappet
Camshaft “break-in” The lobes of the cam and the bottom of
the lifters must be coated with a molydisulfide lubricant often called “cam lube”. This insures that the cam is properly
lubricated during “break-in”.
![Page 62: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/62.jpg)
![Page 63: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/63.jpg)
Hydraulic flat-tappet
Camshaft “break-in” Typical procedure –
Maintain 1,500 RPM for 10 - 20 minutes Drain the engine oil a immediately
afterwards
Check the recommended procedure and lube for your
particular cam!
![Page 64: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/64.jpg)
Hydraulic Roller The lifter is “spring”
and oil loaded to allow for compensation.
The contact between the cam and lifters are separated by a steel roller. This roller reduces
friction. Lifters cannot be
allowed to rotate within the lifter bore.
![Page 65: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/65.jpg)
Hydraulic Roller A roller camshaft is generally
made of non-hardened steel. The lobes must be “finished” by
the manufacturer prior to assembly there is no “break-in period”.
![Page 66: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/66.jpg)
Hydraulic Lifters (tappets) Hollow cylinders
fitted with a plunger, check valve, spring and push-rod seat.
![Page 67: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/67.jpg)
Hydraulic Lifters (tappets)
![Page 68: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/68.jpg)
Hydraulic Lifters
The oil passed through the check valve exits through the hole in the push rod seat.
The oil then passes through the pushrod to lubricate the rocker arms.
![Page 69: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/69.jpg)
A cross-sectional view of a typical flat-bottomed hydraulic lifter.
•Engine oil pressure forces oil into the lifter through the oil inlet holes.•A check valve and ball hold most of the oil inside the lifter “hydro-locking” the plunger inside the cylinder.
![Page 70: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/70.jpg)
Hydraulic Lifter Preload Also called valve lash. The distance between the pushrod
seat and snap-ring when the lifter is resting on its base circle.
Typical values range from .020 to .045”.
Check manufacturers specifications.
![Page 71: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/71.jpg)
To correctly adjust the valve clearance (lash), position the camshaft on the base circle of the camshaft lobe for the valve being adjusted.
Remove all clearance by spinning the pushrod and tightening the nut unit all clearance is removed.
The adjusting nut is then tightened one complete revolution. This is what is meant by the term “zero lash plus 1 turn.”
End of show
![Page 72: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/72.jpg)
Hydraulic Lifter Preload Adjusted by:
Adjustable rocker arms Often referenced by “turns past
zero lash” Non-adjustable rocker arms
Longer or shorter pushrods Shim or grind rocker stands
![Page 73: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/73.jpg)
Hydraulic Lifter Preload Necessary if:
Cylinder head has been decked Cam has been changed Altered head gaskets Camshaft is worn An engine rebuild
![Page 74: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/74.jpg)
Hydraulic Lifter Valve-floatNOT GOOD
The lifter fills with oil faster than it can purge it. This raises the lift of the camshaft.
Usually caused by excessive RPM.
May damage valves, pushrods, pistons etc.
![Page 75: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/75.jpg)
Solid Flat-tappet and Roller No internal hydraulic absorption.
Allows for a more consistent valve lift, especially at high RPM.
Noisy when cold, more frequent and precise valve-lash adjustments required.
![Page 76: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/76.jpg)
Solid Flat-tappet and Roller
Oil is diverted through the
pushrods via a
pushrod seat.
![Page 77: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/77.jpg)
Solid Flat-tappet and Roller No lifter preload – valve lash only. Lash values may be given hot or
cold Typical values range from .002
- .005”.
![Page 78: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/78.jpg)
Cam Specifications Lift Duration Valve overlap Lobe center (separation angle or
lobe spread)
![Page 79: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/79.jpg)
Lobe Lift The amount the cam lobe lifts
the lifter Expressed in decimal inches
As lift increases the forces on the entire valve train
also increase.
![Page 80: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/80.jpg)
The lobe lift is the amount the cam lobe lifts the lifter.
Because the rocker arm adds to this amount, the entire valve train has to be considered when selecting a camshaft that has the desired lift and duration.
![Page 81: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/81.jpg)
A 1.5:1 ratio rocker arm means that dimension A is 1.5 times the length of B.
Therefore, if the pushrod is moved up 0.400 inch by the camshaft lobe, the valve will be pushed down (opened) 0.400 inch X 1.5, or 0.600 inch.
![Page 82: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/82.jpg)
Lobe Lift Asymmetrical design – the amount
of lift between the intake and exhaust lobes is different.
Symmetrical design - the amount of lift between the intake and exhaust lobes is the same.
![Page 83: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/83.jpg)
Duration The number of degrees of
crankshaft rotation for which the valve is lifted off of the seat. If the amount of degrees that the
intake and exhaust valve are open differ – it is of an asymmetrical design.
![Page 84: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/84.jpg)
DurationUsually expressed as one of two
values
Duration (at zero lash) Duration at .050” lift – preferred
method Compensates for tappet styles and
clearances
![Page 85: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/85.jpg)
Duration More duration = rougher idle and
better high RPM performance Less duration = smoother idle and
better low RPM performance
![Page 86: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/86.jpg)
Valve Overlap The number of degrees of
crankshaft rotation that both valves are off of their seat (between the exhaust and intake strokes). Lower overlap = a smoother idle and
better low RPM operation Higher overlap = better high RPM
operation
![Page 87: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/87.jpg)
Valve Overlap Having the exhaust
valve still open when the intake starts to open uses the exhaust "pull" out the exhaust port to help start the intake charge entering the chamber -- before the piston has started down and has generated it's own vacuum.
![Page 88: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/88.jpg)
Lobe Separation Angle The difference, in degrees,
between the center of the intake lobe and the center of the exhaust valve. The smaller the angle the
greater the valve overlap The larger the angle the
less the overlap Link to LSA effects
![Page 89: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/89.jpg)
Camshaft (Valve) Timing
It is crucial that the crankshaft, camshaft and balancing shaft (if equipped) are timed correctly.
This is often achieved by aligning “timing marks” on the gears
Pushrod- Type Engine
![Page 90: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/90.jpg)
Modern DOHC motors may incorporate chains and belts on the same motor
Some of these designs are quite elaborate
Camshaft (Valve) TimingV-type DOHC Design
![Page 91: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/91.jpg)
Some designs do not provide “alignment marks” and require special tools for proper timing
Camshaft (Valve) Timing
![Page 92: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/92.jpg)
Camshaft Degreeing Advanced cam timing
The camshaft is slightly ahead of the crankshaft
More low speed torque less high RPM power
Retarded timing – The camshaft is slightly behind the
crankshaft More high RPM power Reduced low RPM torque
![Page 93: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/93.jpg)
![Page 94: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/94.jpg)
Adjustable Camshaft Gear
![Page 95: Cylinder Heads and Valves. Cylinder Heads Purpose – regulates the air/fuel in/out of the engine Construction Cast Iron Cast Aluminum Overhead valve heads](https://reader033.vdocuments.us/reader033/viewer/2022061422/56649d875503460f94a6c03b/html5/thumbnails/95.jpg)