by iOnic » Tue Dec 22, 2009 11:03 am
I wouldn't try degree'ing the cams unless you know what you're doing and have ALL the specs for the cams you're installing. Here is a basic how-to on doing it though.
1. Use a pencil, paper and arithmetic for this procedure, to keep track of the results.
2. Fashion a rigid pointer from stiff wire or an old coat hanger and attach it to the engine block. This pointer locates the degrees on the degree wheel.
3. With a degree wheel installed on the crankshaft, rotate the crank to get the no 1- piston at TDC and check to ensure that the valves are fully closed then adjust the pointer to zero (0º TDC) on the degree wheel.
4. Turn the crankshaft opposite the running rotation approximately 15-20 degrees. Install a piston stop on the top of the engine block fastened in place by two head bolts.
5. Continue to turn the engine in the same direction until the piston comes back up and just touches the piston stop. Make a note of the exact number on the degree wheel that the pointer is on.
6. Rotate the engine in the other direction (running rotation) until the piston comes back up and touches the piston stop. Again note the number where the pointer is.
7. Remove the piston stop and rotate the crankshaft to the midpoint of the two marks. At this point the piston is at the true top dead center. Loosen the degree wheel and adjust it so it will read 0º TDC at the pointer. Don't rotate the crankshaft to do this!
8. Now, it's time to locate the lobe centerline relative to TDC. Attach a dial indicator on the top of the engine block. Set the tip to contact the top of the no 1-cylinder inlet valve shim/bucket. Check to make sure that the indicator plunger is parallel to the valve stem. NOTE - any variance in an angle will produce geometric errors in the lift readings.
9. Rotate the engine in the normal direction of rotation until a reading on the dial gauge of 0.040” lift is reached. (Valve will start to open) Mark the dial gauge and make a note of the reading on the degree wheel.
10. Continue to turn the engine in the normal direction past maximum lift. The valve will now return to its close position. Make a note of the degree wheel reading when the indicator reads 0.040" on the return side
11. Now add the larger of the two readings that you noted on the degree wheel to 180 subtract the smaller number and then divide the answer by two. Your answer will indicate the lobe center of the cam. Example: open reading was 4 and close reading was 43. Now add 43 to 180 = 223, subtract 4 =219 divide by 2 = 109.5. Lobe center is 109.5 degrees.
12. Continue to move the cam on the adjustable cam gear and redo steps 10 to 12 until the required lobe center is achieved.
13. Now do the same for the exhaust cam
Faber est suae quisque fortunae
2009 Mazda3 MPS
2016 CFMoto 650NKs
2013 Hyundai IX35 Highlander