Post by DOCTOR FIELDS on Mar 4, 2008 23:34:27 GMT -5
It's important you use a solid lifter if you don't have them already when degreeing in a cam. Only install the #1 cylinder intake and exhaust rockers / lifters. This will "free up" the engine and make it easier to rotate during the degreeing process. Set the #1 intake lifter to zero lash, which means there's no clearance between the rocker tip and lash cap. You don't want to go past zero and be holding the valve open, just keep adjusting and moving the rocker arm until it just starts getting tight. You shouldn't be able to get any feeler gauges under it at this point. Follow the rest of the steps from Comp Cams and you should be in good shape...
Step 3: Attach the pointer to the block. Many people will make a pointer out of some sort of rigid, yet
manageable wire. A stiff coat hanger wire works well.
Step 4: Attach the degree wheel to the balancer and install the assembly on the crankshaft. There are
several ways to attach the degree wheel to the crankshaft. The crank may be rotated from either the
front or from the flywheel end. Obviously, if the engine is in the car, you must rotate from the front.
Remember, the greater the leverage, the smoother the crank rotation, thus more accuracy. Note: Never
use the starter to turn the engine while degreeing a cam.
Step 5: Before installing the piston stop, rotate the crankshaft to get the #1 piston in approximate TDC
position with both the intake and exhaust valves closed. This can be a rough guess, but it can save you
from making a mistake later. Adjust you pointer to zero or TDC on the degree wheel.
Step 6: Turn the crankshaft opposite the engine rotation approximately 15-20 degrees. This will lower
the position enough to allow the TDC stop to be installed in the spark plug hole. Screw in the piston
stop until it touches the piston. Continue to turn the engine in the same direction until the piston comes
back up and touches the piston stop. Mark the degree wheel with a pen or pencil on the number the
pointer is on. Turn the engine in the other direction, same as engine rotation, until the piston comes
back up and touches the piston stop. Make a mark on the number the pointer is on.
Step 7: Remove the piston stop after marking the two points on you degree wheel. Rotate the
crankshaft to the midpoint of the two marks. This point is TDC for cylinder #1. Without rotating the
crankshaft, adjust the degree wheel to read 0 degrees at the pointer. You are now ready to locate the
intake lobe centerline relative to TDC. If you are not absolutely sure that your 0 degree mark is set at
TDC, repeat this procedure. This step by step is critical to proper cam alignment.
Step 8: Attach the dial indicator to the dial indicator mount. Position the dial indicator mount so the
tip will contact the retainer of the intake valve. It is important that the indicator plunger be parallel to
the valve stem. Any variance in the angle of the indicator will introduce geometric errors into the lift
readings.
Step 9: Rotate the engine in the normal direction of rotation until you reach maximum lift. The dial
indicator will change direction at the point of maximum lift. At this point, set the dial to zero.
10
Step 10: Back the engine up (opposite normal rotation) until the indicator reads .100.” Next, turn the
engine forward in the normal direction of rotation until the dial indicator reads .050” before maximum
lift. Record the degree wheel reading.
Step 11: Continue to rotate the engine over in its normal direction of rotation until the indicator goes
past zero to .050” on the closing side of maximum lift. Again, record the degree wheel reading.
Step 12: Add the 2 numbers together and dived by 2. That number will be the location of maximum
lift of the intake lobe in relation to the crank and piston. This is the intake centerline. For example:
The first degree wheel reading was 96 degrees. The second reading was 116 degrees. These two
numbers (96 + 116) added together will be 212. 212 divided by 2 will equal 106. Your actual intake
centerline is 106 degrees. Reference back to your cam spec card and see what the recommended intake
centerline is.
In the event that your camshaft did not degree in as per manufacturers’ specs, it will be necessary to
either advance (move the cam ahead) or retard (move the cam back) the cam to meet the suggested
intake centerline. Depending on the engine application, there are several different ways for advancing
or retarding the camshaft. A second method is to use offset
bushings that fit on the cam pin and in the cam gear. The offset will advance or retard the cam
depending on how the bushing is placed on the cam pin. A more elaborate system uses an adjustable timing gear. Contact COMP
Cams® for the method best suited to your application.
Note: When degreeing a cam, remember to look at the degree wheel as a full 360 degrees no matter
how the degree wheel you are using is marked. Many degree wheels are marked in 90 or 180 degree
increments. On wheels that are marked in 90 degree increments, keep in mind that you must
continue to count the number of degrees on past 90 degrees. Be sure all readings are taken from
Top Dead Center.
Keep in mind that to advance the cam, you must lower the intake centerline. For example, if our cam
has a lobe separation of 110 degrees. Moving the centerline to 106 degrees advances the cam 4
degrees. If we change the centerline to 112 degrees, this would be 2 degrees retarded.
Step 3: Attach the pointer to the block. Many people will make a pointer out of some sort of rigid, yet
manageable wire. A stiff coat hanger wire works well.
Step 4: Attach the degree wheel to the balancer and install the assembly on the crankshaft. There are
several ways to attach the degree wheel to the crankshaft. The crank may be rotated from either the
front or from the flywheel end. Obviously, if the engine is in the car, you must rotate from the front.
Remember, the greater the leverage, the smoother the crank rotation, thus more accuracy. Note: Never
use the starter to turn the engine while degreeing a cam.
Step 5: Before installing the piston stop, rotate the crankshaft to get the #1 piston in approximate TDC
position with both the intake and exhaust valves closed. This can be a rough guess, but it can save you
from making a mistake later. Adjust you pointer to zero or TDC on the degree wheel.
Step 6: Turn the crankshaft opposite the engine rotation approximately 15-20 degrees. This will lower
the position enough to allow the TDC stop to be installed in the spark plug hole. Screw in the piston
stop until it touches the piston. Continue to turn the engine in the same direction until the piston comes
back up and touches the piston stop. Mark the degree wheel with a pen or pencil on the number the
pointer is on. Turn the engine in the other direction, same as engine rotation, until the piston comes
back up and touches the piston stop. Make a mark on the number the pointer is on.
Step 7: Remove the piston stop after marking the two points on you degree wheel. Rotate the
crankshaft to the midpoint of the two marks. This point is TDC for cylinder #1. Without rotating the
crankshaft, adjust the degree wheel to read 0 degrees at the pointer. You are now ready to locate the
intake lobe centerline relative to TDC. If you are not absolutely sure that your 0 degree mark is set at
TDC, repeat this procedure. This step by step is critical to proper cam alignment.
Step 8: Attach the dial indicator to the dial indicator mount. Position the dial indicator mount so the
tip will contact the retainer of the intake valve. It is important that the indicator plunger be parallel to
the valve stem. Any variance in the angle of the indicator will introduce geometric errors into the lift
readings.
Step 9: Rotate the engine in the normal direction of rotation until you reach maximum lift. The dial
indicator will change direction at the point of maximum lift. At this point, set the dial to zero.
10
Step 10: Back the engine up (opposite normal rotation) until the indicator reads .100.” Next, turn the
engine forward in the normal direction of rotation until the dial indicator reads .050” before maximum
lift. Record the degree wheel reading.
Step 11: Continue to rotate the engine over in its normal direction of rotation until the indicator goes
past zero to .050” on the closing side of maximum lift. Again, record the degree wheel reading.
Step 12: Add the 2 numbers together and dived by 2. That number will be the location of maximum
lift of the intake lobe in relation to the crank and piston. This is the intake centerline. For example:
The first degree wheel reading was 96 degrees. The second reading was 116 degrees. These two
numbers (96 + 116) added together will be 212. 212 divided by 2 will equal 106. Your actual intake
centerline is 106 degrees. Reference back to your cam spec card and see what the recommended intake
centerline is.
In the event that your camshaft did not degree in as per manufacturers’ specs, it will be necessary to
either advance (move the cam ahead) or retard (move the cam back) the cam to meet the suggested
intake centerline. Depending on the engine application, there are several different ways for advancing
or retarding the camshaft. A second method is to use offset
bushings that fit on the cam pin and in the cam gear. The offset will advance or retard the cam
depending on how the bushing is placed on the cam pin. A more elaborate system uses an adjustable timing gear. Contact COMP
Cams® for the method best suited to your application.
Note: When degreeing a cam, remember to look at the degree wheel as a full 360 degrees no matter
how the degree wheel you are using is marked. Many degree wheels are marked in 90 or 180 degree
increments. On wheels that are marked in 90 degree increments, keep in mind that you must
continue to count the number of degrees on past 90 degrees. Be sure all readings are taken from
Top Dead Center.
Keep in mind that to advance the cam, you must lower the intake centerline. For example, if our cam
has a lobe separation of 110 degrees. Moving the centerline to 106 degrees advances the cam 4
degrees. If we change the centerline to 112 degrees, this would be 2 degrees retarded.
