Cam Sensor Adjustment Procedure
Ken Mosher
Cam Sensor Adjustment Procedure
1. Measure on a piece of masking tape and mark it at 1.45" and tape it to the Balancer at 0 degrees.
2. Bring #1 to TDC and then grab the intercooler fan and rotate the motor to your mark (25 degrees ATDC). This takes a little patience and muscle. You can try bumping it with the starter, but I'm never very successful at that.
3. Back probe the middle wire of the cam sensor (marked B and normally blue) with a voltmeter. Turn the key ON, but leave the engine OFF.
4. Loosen the sensor with a distributor wrench or a wobble socket and extension.
5. Rotate the sensor full CLOCKWISE. The voltmeter should read 7.5+ volts.
6. Slowly rotate the sensor COUNTER clockwise until the voltage drops.
7. Secure the sensor at the instant the voltage drops.

The sensor is a hall effect device with a rotating metal ring that is driven from the front of the cam gear via a shaft (like a distributor). This ring passes thru a grooved sensor molded into the sensor cap. The metal ring has a notch or window cut out of it. When the window goes by the sensor, the voltage drops, which tells the ECM where #1 TDC is.

Jim Frankovich has done some measuring and calculating and has the following input:

  • 20º = 1.160"
  • 21º = 1.218"
  • 22º = 1.276"
  • 23º = 1.334"
  • 24º = 1.392"
  • 25º = 1.450"
  • 30º = 1.740"
  • Every degree figures out to be about 0.058"

Several people have found that when running a bigger cam with advanced valve timing, it sometimes will help cure a popping or sputtering symptom by advancing the cam sensor a few degrees. The above values give you an idea of what to shoot for.

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