Helping a friend reinstall engine into 1986 GN Engine was rebuilt and am sensor installed with electronic tool? This is what the engine builder told me. I need to remove the cam sensor to prime oil pump and engine. Hw do I reinstall the cam sensor and get it adjusted correctly. I remember engine builder saying something that itneeds to be set 5* before TDC and that u need a special electronic toolto set the cam sensor. Can anyone tell me how or where to find the procedure for this and where to get a tool. Is this something that can be loaned out from like NAPA or Autzone etc? Thanks Mark
Cam Sensor Install
- Thread starter msharkf2
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TurboTdr3.8
Well-Known Member
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- Jan 15, 2013
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Cam Sensor
The cam sensor has nothing to do with ignition timing. Its primary purpose is to locate cylinder #6 in order to synch injector pulse to the the correct cylinder on the intake stroke so that the injector sprays at the proper point in the intake cycle and to the correct cylinder.
If the cam sensor is not working, the engine will not start.
If it is bad, you will have no start due to no injector pulse. See the troubleshooting pages.
Once the engine has been started, the cam sensor may be disconnected and the engine will continue to run. The ecm has been told where number 6 is and the spark will continue to be correct. What does change is the technique of applying injector pulses. The injectors will normally fire in a sequential mode. If the cam sensor is disconnected after starting the engine, the injectors start firing in batch mode. In the early days, we often put a switch on the cam sensor and turned it off before making a run thinking that the engine might get more fuel that way. Later we decided that that might not be true, and, we had a lot better selection of injectors, fuel pumps, chips, etc. to cover the fuel problem. At wide open throttle, the injectors are probably on as long as they can be with regard to duty cycle so this should not be beneficial with today's larger injectors.
Note that the cam sensor must be reconnected again or the engine will not start after being shut off.
So, remember that the cam sensor controls the point that the injector sprays, but not ignition timing.
In order for the engine to start, and to run properly, the cam sensor must be installed correctly. Go here for install directions. Note that the new Casper's replacement cap is installed with the timing mark set at zero rather than 25 degs ATDC. It has an led in the top that comes on when the cam sensor is installed correctly, and, this greatly simplifies installation if the sensor has been removed, or, the original cap has failed. Read the instructions that come with it and ignore the install directions I have provided.
I highly suggest reading the cam sensor article on GNTTYPE by Tom Chou who worked at Delco. It explains in detail the workings of the sensor and what it does.
For years, a number of experienced Buick guys have suggested moving the cam sensor about 1/8" counterclockwise from the theoretical setting point especially if you have a modified engine with a larger cam. I always do, myself. This has absolutely nothing to do with ignition timing, but, it does alter the point where the injectors begin to spray. It might help engines with larger cams as prior stated. If moved so much that the sensor is on the wrong (next) window, it will probably backfire very badly and that ain't good.
After 25 years, or so, there has to be some wear in the original cam sensor gear. This leads to increased vertical movement in the reluctor shaft as well as more potential shift in the reluctor window from its desired setting because the increased clearance in the teeth and the vertical movement of the shaft allows some small rotation. This can move the reluctor window a bit from the set point and/or allow the window to shift vertically in its relationship to the magnet. This can cause a miss at part throttle and at low boost.
One fix may be the installation of some distributor shaft shims (Mr. Gasket 2820) to get the vertical movement of the shaft down to 0.040" or so. The other is the aforementioned clocking of the cam sensor an additional 1/8".
When the sensor is installed 180 degrees out (as if you were not on top dead center, but were one crank revolution out), then the fuel will be sprayed on the exhaust stroke rather than the intake stroke and the engine will idle badly, and generally not run well at all. Make sure the crank is properly referenced to TDC before you install the sensor.
The cam sensor has nothing to do with ignition timing. Its primary purpose is to locate cylinder #6 in order to synch injector pulse to the the correct cylinder on the intake stroke so that the injector sprays at the proper point in the intake cycle and to the correct cylinder.
If the cam sensor is not working, the engine will not start.
If it is bad, you will have no start due to no injector pulse. See the troubleshooting pages.
Once the engine has been started, the cam sensor may be disconnected and the engine will continue to run. The ecm has been told where number 6 is and the spark will continue to be correct. What does change is the technique of applying injector pulses. The injectors will normally fire in a sequential mode. If the cam sensor is disconnected after starting the engine, the injectors start firing in batch mode. In the early days, we often put a switch on the cam sensor and turned it off before making a run thinking that the engine might get more fuel that way. Later we decided that that might not be true, and, we had a lot better selection of injectors, fuel pumps, chips, etc. to cover the fuel problem. At wide open throttle, the injectors are probably on as long as they can be with regard to duty cycle so this should not be beneficial with today's larger injectors.
Note that the cam sensor must be reconnected again or the engine will not start after being shut off.
So, remember that the cam sensor controls the point that the injector sprays, but not ignition timing.
In order for the engine to start, and to run properly, the cam sensor must be installed correctly. Go here for install directions. Note that the new Casper's replacement cap is installed with the timing mark set at zero rather than 25 degs ATDC. It has an led in the top that comes on when the cam sensor is installed correctly, and, this greatly simplifies installation if the sensor has been removed, or, the original cap has failed. Read the instructions that come with it and ignore the install directions I have provided.
I highly suggest reading the cam sensor article on GNTTYPE by Tom Chou who worked at Delco. It explains in detail the workings of the sensor and what it does.
For years, a number of experienced Buick guys have suggested moving the cam sensor about 1/8" counterclockwise from the theoretical setting point especially if you have a modified engine with a larger cam. I always do, myself. This has absolutely nothing to do with ignition timing, but, it does alter the point where the injectors begin to spray. It might help engines with larger cams as prior stated. If moved so much that the sensor is on the wrong (next) window, it will probably backfire very badly and that ain't good.
After 25 years, or so, there has to be some wear in the original cam sensor gear. This leads to increased vertical movement in the reluctor shaft as well as more potential shift in the reluctor window from its desired setting because the increased clearance in the teeth and the vertical movement of the shaft allows some small rotation. This can move the reluctor window a bit from the set point and/or allow the window to shift vertically in its relationship to the magnet. This can cause a miss at part throttle and at low boost.
One fix may be the installation of some distributor shaft shims (Mr. Gasket 2820) to get the vertical movement of the shaft down to 0.040" or so. The other is the aforementioned clocking of the cam sensor an additional 1/8".
When the sensor is installed 180 degrees out (as if you were not on top dead center, but were one crank revolution out), then the fuel will be sprayed on the exhaust stroke rather than the intake stroke and the engine will idle badly, and generally not run well at all. Make sure the crank is properly referenced to TDC before you install the sensor.
GNONYX
Well-Known Member
- Joined
- Oct 16, 2009
- Messages
- 1,761
Before doing anything with the cam sensor, you must have oil pressure present before you start the engine or you will be rebuilding the engine again.
Here's what I did to get oil pressure before starting the engine:
I first filled the oil filter as much as I can and place back onto engine, and then put about 3 quarts oil in the oil pan, then I remove the lower oil cooler from the radiator taped it against some pipe so the oil cooler hose is in the vertical position. Place a small funnel inside the oil cooler hose, you will need a Chevy oil pump prime tool and place it inside the Cam Sensor hole; make sure the tool slot is fitted on the oil pump shaft. DO NOT START THE ENGINE, if your oil pressure gauge is electric then just turn the key to the "ON POSITION" , and have someone inside the car telling you that you have oil pressure. Attach the cordless drill machine to prime tool and run it at CCW position, at the same time fill the oil cooler hose with about 1-1/2-2 quarts of motor oil, or until you have oil pressure present. Once you have oil pressure, re-install the oil cooler hose back, set the cordless drill machine to CW until the other person inside the car tells you that you oil pressure on the gauge.
Now that you do have oil pressure present showing on your oil pressure gauge read this Casper's Cam Set Tool instruction ant it will show you where place the mark on the harmonic balancer.
Here's what I did to get oil pressure before starting the engine:
I first filled the oil filter as much as I can and place back onto engine, and then put about 3 quarts oil in the oil pan, then I remove the lower oil cooler from the radiator taped it against some pipe so the oil cooler hose is in the vertical position. Place a small funnel inside the oil cooler hose, you will need a Chevy oil pump prime tool and place it inside the Cam Sensor hole; make sure the tool slot is fitted on the oil pump shaft. DO NOT START THE ENGINE, if your oil pressure gauge is electric then just turn the key to the "ON POSITION" , and have someone inside the car telling you that you have oil pressure. Attach the cordless drill machine to prime tool and run it at CCW position, at the same time fill the oil cooler hose with about 1-1/2-2 quarts of motor oil, or until you have oil pressure present. Once you have oil pressure, re-install the oil cooler hose back, set the cordless drill machine to CW until the other person inside the car tells you that you oil pressure on the gauge.
Now that you do have oil pressure present showing on your oil pressure gauge read this Casper's Cam Set Tool instruction ant it will show you where place the mark on the harmonic balancer.
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