Tech Notes:


LC Adjustable Cam Gear


1022003 - Cam Gear - 20R/22R Dual Row Adjustable Camshaft Gear
1022006 - Cam Gear - 20R/22R Single Row Adjustable Camshaft Gear
1022009 - Cam Gear - 2RZ/3RZ Adjustable Intake Camshaft Gear (95-03)

Using an LC Engineering Performance Single or Double Adjustable Cam Gear is the only way to accurately degree the camshaft to its proper specifications. For Electric Fuel Pump applications, we recommend using the LC Pro Fuel Pump part # 1035045. It is possible to run a Manual Fuel Pump with an adjustable cam gear by doing the following: 1) Remove allen head bolts and turn them around in the cam gear (allen heads outward). 2) Mark and machine the fuel pump concentric drive to clear the allen head bolts used on the cam gear (machining the concentric drive too deep may cause the drive arm to fall into the machined slots where damage will occur). Note: If you do not use the fuel pump drive, you must space the distributor drive gear out the same thickness (0.90?) as the fuel pump concentric or damage will occur to the distributor drive gear.

Camshaft Degreeing Procedures
NOTE: The zero marking on an adjustable camshaft gear is not always in direct correlation with the camshaft centerline. Because of the numerous variations in engine mechanics, including cylinder head decking, cylinder block decking, camshaft size, etc., which play an important role in overall camshaft timing, LCE recommends the following in the initial set up of your new adjustable camshaft gear.

Basic Camshaft Gear Installation:
With the #1 cylinder at TDC (top dead center), remove the factory timing gear from the camshaft. Be careful to not let the timing chain fall below the timing chain cover.

Set the factory camshaft gear on a flat surface and place the adjustable camshaft gear on top (make sure that the nuts on the adjustable cam gear are loose first). Line up the camshaft dowel holes on both gears. With the holes in the center hubs lined up, rotate the outer gear of the adjustable camshaft gear to line up with the factory teeth (make sure that the dowell holes on both center hubs still match). Tighten the nuts on the adjustable cam gear and make a mark (using a chisel) on the outer gear at the ?zero? mark of the adjustable camshaft gear.

Install the adjustable camshaft gear onto the camshaft with the timing chain and secure. You will now be able to advance or retard the camshaft timing accordingly.

Advanced Camshaft Gear Installation:
We recommend the Intake Lobe Center Method to degree the camshaft. This will achieve the most accurate settings available, resulting in the best performance from your engine package.

Setup Procedures. Install the degree wheel on the crankshaft. Using a stiff wire, form a pointer. Position it off of one of the 6mm water pump bolts.

To set true piston TDC (top dead center) on the degree wheel with the cylinder head installed. Rotate the crank shaft to position the #1 piston at BDC (bottom dead center). Install a piston stop, into the #1 cylinder spark plug hole and tighten. Loosen the cam bolt so the cam gear can be pulled off the cam, but still supported on the bolt. Carefully rotate the crankshaft clockwise until the piston touches the piston stop. Read the degree wheel. Example 15° ATDC (after top dead center). Rotate the crank counter clockwise until it reaches the piston stop. Example 25° BTDC (before top dead center).

Move the wire pointer to split the difference of these two readings (20°). The wheel should read the same at both sides of TDC at the cylinder stop. If not, adjust the pointer until it is accurate. Remove the piston stop and tighten the cam gear bolt to 60 ft lbs.

Using a 1\" travel dial indicator with a magnetic base and fixture plate position the indicator on the #1 intake valve retainer at the same plane as the valve.

Cam Card Specifications. Review the cam card provided with your camshaft. Find the intake center line the cam was ground on. If not provided you can compute the center line by adding the intake opening degrees at .050 valve lift to the intake close degrees at .050 valve lift plus 180° crank rotation. Divide this number by 2 and subtract the smaller number. This is your intake center line of the cam you are about to degree. Check every cam, they will differ from cam to cam. Example:

Opens 13° + Closes 37° + 180° = 230°
230° ÷ 2 = 115°
115° - 13° = 102° Lobe Center

Note: Always rotate the crankshaft in the running rotation (clockwise looking at the front of the engine). Never reverse crankshaft rotation to achieve a reading when degreeing the camshaft.

Step 1: Find Valve Open @ .050 Lift. With your indicator on the retainer and the rocker set at zero lash on the base circle, zero the dial indicator. Rotate the crank until the indicator reads .050 valve lift off base circle. Read the degree wheel and record. Example would be 11° on the degree wheel BTDC.

Step 2: Find Valve Closes @ .050 Lift. Rotate the crankshaft until the dial indicator reads .050 off the base circle (valve closing). Read the degree wheel and record. Example 39° on the degree wheel ABDC.

Step 3: Calculate Lobe Center. To figure the exact lobe center add intake open number and intake close number plus 180°. Divide this total by 2 and subtract the smaller number (usually the intake open number). Example:

Intake open 11° + Intake close 39° + 180° = 230°
230° Duration ÷ 2 = 115°
115° - 11° = 104° Lobe Center

In our example your cam is currently set to a 104° Lobe Center. Compare your actual findings with the information from your cam card and adjust the cam accordingly.

Step 4: Adjusting The Camshaft. Loosen the three 10mm lock nuts on the cam gear. Advance or retard the gear to achieve the proper intake center line for your specific cam. Torque the nuts to 8 ft. lb. And recheck your numbers to assure a proper setting.

Once indexed correctly, using a sharp small chisel, align with the zero mark on the gear hub and make a reference mark on the outer gear for future reference. You have now completed the degreeing process.

Calculating Duration: To calculate duration at .050 valve lift . Add the degrees when the valve opens @ .050 to the degrees the valve closes @ .050 plus 180°. Example:

Opens 11° + Closes 39° + 180° = 230° Duration @ .050 Valve Lift

Performance Tips

To change the performance of your engine, you can advance the cam to achieve a lower RPM torque curve (bottom end power) or retard the cam to achieve a higher RPM torque curve (top end power). Make small adjustments and record your results. This way you can always refer back to your previous settings.

Ignition timing and cam timing are not the same. Since the distributor is turned by the camshaft, always recheck your ignition timing after adjusting the cam timing.

For additional technical information contact LC Engineering at 928-505-2501

Return to Tech Engine Main Page