timing question
#11
07-31-2011, 01:17 PM
Thing is, the sensor is still in the same place...... so, if you turn the rotor and shaft 180 out, the window, or open portion, isn't going to be in correct phase with where the PCM actually thinks the motor is, as the sensor will be working exactly opposite of what the PCM expects. (unless there is a specific spot on the flexplate the crank sensor reads to indicate number 1 cylinder? and would the PCM be programed to notice that things were "different" than what it originally expects???)
#12
07-31-2011, 02:44 PM
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#13
07-31-2011, 04:07 PM
Legend
Hang on a minute, lemme think this thru...
The disty has a flat notch in the bottom, that notch connects to the oil pump drive gear. The disty shaft moves the rotor and the tone ring, not the housing. The housing holds the cam position sensor, and it only mounts in one way (square and round ear with groove for the plug). It cannot be put in backward.
The rotor also only mounts one way, grooved slot in it. The tone ring and the rotor cannot get out of sync, they are stuck in the same pattern as they are both connected to the disty drive shaft. If only the distributor gear was put in backward, so at tdc #1 the rotor was actually pointing at #6 instead of #1, you could still put the housing on the correct way (the square and round ears on the correct side with the plug coming out of the back) and you would indeed be 180* off and the truck would not fire.
You then have 3 options: pull the disty shaft and spin it 180*, twist the housing 180* so the ears are backward and the cam sensor plug comes out the front, or you could wire the cap backward so the number 6 plug would be where the #1 mark on the cap is and follow the firing pattern from there. The #1 plug would go where the #6 Plug should be, but under that cap the rotor is pointing at that number 6 cylinder, so the engine is at #1 TDC compression stroke, the rotor is there at #6 ready to fire the plug, but you put the #1 wire there, so it fires correctly even though everything is a mess.
The disty has a flat notch in the bottom, that notch connects to the oil pump drive gear. The disty shaft moves the rotor and the tone ring, not the housing. The housing holds the cam position sensor, and it only mounts in one way (square and round ear with groove for the plug). It cannot be put in backward.
The rotor also only mounts one way, grooved slot in it. The tone ring and the rotor cannot get out of sync, they are stuck in the same pattern as they are both connected to the disty drive shaft. If only the distributor gear was put in backward, so at tdc #1 the rotor was actually pointing at #6 instead of #1, you could still put the housing on the correct way (the square and round ears on the correct side with the plug coming out of the back) and you would indeed be 180* off and the truck would not fire.
You then have 3 options: pull the disty shaft and spin it 180*, twist the housing 180* so the ears are backward and the cam sensor plug comes out the front, or you could wire the cap backward so the number 6 plug would be where the #1 mark on the cap is and follow the firing pattern from there. The #1 plug would go where the #6 Plug should be, but under that cap the rotor is pointing at that number 6 cylinder, so the engine is at #1 TDC compression stroke, the rotor is there at #6 ready to fire the plug, but you put the #1 wire there, so it fires correctly even though everything is a mess.
Last edited by aim4squirrels; 07-31-2011 at 06:15 PM.
#15
07-31-2011, 06:11 PM
Legend
#16
07-31-2011, 06:38 PM
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#17
07-31-2011, 07:05 PM
Legend
#18
07-31-2011, 07:58 PM
Record Breaker
Yes, that is exactly correct about the ring, its 180* of the total revolution. But with the disty in 180* off, the pick up in the cam sensor is 180* off. Starting the firing order at #1 where #6 should be puts the firing order 180* off as well, so everything is lined up "correctly incorrect."
The thing that throws me is the cam overlap, and how that is firing correctly. He must have put the cam in at what he thought was #1 TDC compression, and it was actually #6 TDC compression (cam and crank dots facing each other at 6 & 12 O'clock, then put the engine together and realized it was off and did this to fix the problem instead of tearing everything back apart..
I think thats right, hell, im confusing myself now.
The thing that throws me is the cam overlap, and how that is firing correctly. He must have put the cam in at what he thought was #1 TDC compression, and it was actually #6 TDC compression (cam and crank dots facing each other at 6 & 12 O'clock, then put the engine together and realized it was off and did this to fix the problem instead of tearing everything back apart..
I think thats right, hell, im confusing myself now.
The cam has to be correctly installed because no matter where you locate the #1 tower at the distributor the plug wire still goes to #1 cylinder and when the rotor reaches the #1 tower it will be trying to fire #1 cylinder on TDC of compression stroke. If cam was timed to #6 TDC I dont think the truck would run?
Does that make sence?
Dave
#19
07-31-2011, 07:59 PM