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Cam Timing - The art of making it all happen at the right time    by Lance W.

Required equipment:  Degree wheel, dial indicator and suitable mount, piston stop (can be fabricated from a used sparkplug and a bolt or screw), a piece of coat hanger wire.

1. Prepare as if you were doing the valve adjustment (in fact this in an opportune time to check the valve lash).

2. If you haven't already removed the radiator (it's way, way easier with the radiator out!) consider the advantages and just do it.

3. Remove the crank balancer centerbolt, attach the degree wheel to the crank nose.  This may require a standoff and a longer bolt if you want to leave the balancer on the engine.

4. Attach the coat hanger wire to the engine at a fixed point and fashion a pointer that points to the degree wheel.

5. Install your piston stop in #1 cylinder preferably with the piston not at TDC.  Be sure the rest of the cylinders have no plugs or the crank will be very difficult to turn.

6. Slowly rotate the crank BY HAND until the piston contacts the piston stop and note the degrees on the degree wheel.

7. Slowly rotate the crank in the opposite direction BY HAND until you contact the piston stop again.  Note the degrees on the degree wheel.

8. TDC is exactly half-way between where your degree wheel stopped on each side.  If you are in the ballpark at all, TDC will already be in the zone that the piston stop prevents you from entering.  If that is the case, you may be able to just move the pointer to get an equal number of degrees on either side of TDC when you rotate back and forth, otherwise you need to reposition the degree wheel to get in the ballpark and have the pointer somewhere visible.  Then you can fine tune by bending your coat hanger wire to exact TDC.

9. Remove your piston stop.  Now that you have located TDC, it is critical that you not move the degree wheel in relation to the crank (by turning the wheel without turning the crank).

10. Install your dial indicator to measure valve travel.  This can be difficult, but the spot to use is beside the cam lobe without the lobe hitting the dial indicator or the dial indicator slipping off the top of the valve adjustment shim.  Be sure to compress the plunger at least 0.400” so that the tip never loses contact with the bucket while the valve is opening and closing.

11. With the valve closed, set your indicator to 0.000"

12. Rotate the engine BY HAND in the normal operating direction until the dial indicator measures a significant lift.  I like 0.040" (1 mm), others prefer 0.050”.  It doesn't matter which measurement you use, as long as it is consistent.  Note the degrees on the degree wheel.  It should be around 3 degrees BEFORE TDC (BTDC), but if it's not don't worry, it just means your measurement is a little different than the factory's.  If it is After TDC (ATDC), consider it a negative number in your calculations.

13. Now continue to rotate around until the valve closes to the same point you used for the opening, and note the number of degrees.  It should be around  50 degrees AFTER BOTTOM DEAD CENTER (ABDC).  Again, don't worry if it's not, just be sure to be consistent with your measurements.

14. Now comes the hard part:  Add your two degree numbers, and 180 degrees.  Divide that number by 2.  Subtract the degrees opening BTDC.  This is when your lobe center occurs ATDC.  The stock setting should be 113.5 degrees.  It may vary as much as 3 degrees on either side of that number depending on your particular engine.

15.  Make your adjustments and note where true 0 degrees is on your cam sprocket indicator.  This will aid you when discussing cam timing with other tuners, since your 0 point will be relative to design spec, not just where your engine happened to end up after all the machining tolerances were added together.

16. Perform steps 10 through 14 for the exhaust cam.  Your numbers will be slightly different, opening will be around 52 degrees Before BDC (BBDC), and closing will be around 4 degrees ATDC.  Perform the same arithmetic, add degrees BBDC to degrees ATDC and 180 degrees.  Divide that by two and subtract degrees ATDC to indicate lobe center BTDC.  Stock is 114.  Just as with the intake, note your cam sprocket's indication when set to the correct factory position.

17. When you tighten everything that adjusts timing, I highly recommend you use Loctite 242 (blue) or equivalent.  An engine is a high vibration, high stress area.  Having your cam timing shift because the adjuster bolts came loose could be disastrous under certain conditions (like high boost on NOS), so put the goop on 'em for safety's sake!

18. Now put it all back together and know that you are precisely in time with stock, or you've made a repeatable advance/retard that you can tell all your buddies about, and they can try it too!