Cam timing inconsistant with each revolution
#1
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So my car is an 86 and I installed the Porkensioner and I am setting the cam timing with the 32v'r. Belt is a new gates and tensioner extension is 5mm. I am revolving the crank two times clockwise and setting the TDC mark by the water pump marker as consistanly as humanly possible. I end up with slightly different measurements each time I rotate two times. It varies as much as 2 deg each time. I have done this 4 times now and I don't know when to stop and just set it. Everything is tight, I even torqued down the 32v'r rings along with the cam bolts, nothing is slipping. What is happening here?
#2
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The only way this could be happening is if the belt had inconsistent spacings on the notches. Unless of course there is a slight degree of inaccuracy in replicating the position of the crank. Any inconsistency there would be doubled at the cams.
#3
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Is the variation on both cams or only the right side? There is a note in the 32v'r instructions about setting the RH cam gear one or two degrees greater than the desired final setting to account for the tendency of the RH cam to move from valve spring pressure when the cam gear bolt is loosened. To get the RH side to show 2deg retard after adjustment and 2 revs to equalize belt tension I had to set the RH gear at 0deg. Once set and then making two full crank revs the pointer lined up at 2deg retard consistently. The LH side never varied and stayed precisely on 0deg as I originally set it through the whole process.
Hope this helps
Hope this helps
#4
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My thoughts are the belt is not fully seated in.
This is the way I do it;
Get the gears as close as you can at 45 deg w/ 32vr, in line w/ crank 45 deg mark.
Snug up the belt at 0 deg Crank
Rotate the crank at least 5 FULL times (see 0 deg pass crank mark 10 x's).
Stop at the next 0 deg on crank.
Set your belt tension w/ a belt tool of your choice, w/ kemph tool I do the high side of window.
Rotate the crank 5 FULL times again and stop at 0 deg and see what you got.
The left side (drivers US) should be dead nuts on the factory gear mark.
The right side should be approx 2 deg advanced (when using a stock tensioner) this will end up at 0 when the eng heats up and the stock tensioner de-tensions the belt (retracts).
If you need to adjust the left side gear or even move the belt on the gear, zip tie the right gear to the belt to keep it set and from moving, release the belt tensioner and make adjustments on the left gear (this includes removing the belt from the gear if needed).
Then do the process all over again until it is correct.
edit: I missed that this was Porkentensioner
Hope this helps.
DaveK9
This is the way I do it;
Get the gears as close as you can at 45 deg w/ 32vr, in line w/ crank 45 deg mark.
Snug up the belt at 0 deg Crank
Rotate the crank at least 5 FULL times (see 0 deg pass crank mark 10 x's).
Stop at the next 0 deg on crank.
Set your belt tension w/ a belt tool of your choice, w/ kemph tool I do the high side of window.
Rotate the crank 5 FULL times again and stop at 0 deg and see what you got.
The left side (drivers US) should be dead nuts on the factory gear mark.
The right side should be approx 2 deg advanced (when using a stock tensioner) this will end up at 0 when the eng heats up and the stock tensioner de-tensions the belt (retracts).
If you need to adjust the left side gear or even move the belt on the gear, zip tie the right gear to the belt to keep it set and from moving, release the belt tensioner and make adjustments on the left gear (this includes removing the belt from the gear if needed).
Then do the process all over again until it is correct.
edit: I missed that this was Porkentensioner
Hope this helps.
DaveK9
Last edited by davek9; 07-17-2010 at 02:16 PM. Reason: corrected rotation x's
#5
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720 degree of crankshaft rotation = 360 degree of cam rotation.
Two degrees at the cam would be four at the crank and I doubt he is missing it by that much.
The only thing that I could think of that possibly could be moving is the tensioner.
#6
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It would only be half at the cams, not doubled.
720 degree of crankshaft rotation = 360 degree of cam rotation.
Two degrees at the cam would be four at the crank and I doubt he is missing it by that much.
The only thing that I could think of that possibly could be moving is the tensioner.
720 degree of crankshaft rotation = 360 degree of cam rotation.
Two degrees at the cam would be four at the crank and I doubt he is missing it by that much.
The only thing that I could think of that possibly could be moving is the tensioner.
Did you pull the pin from the tensioner, and measure the piston extension per the instructions? Is the extension the same each time you check the cam position?
Were the gears clean?
After all that, drive the car for a while, and check timing again. The new belt may have somewhat fat ribs on it that don't sit down all the way into all the gears. A little driving will get the belt and all the gears working a little more closely together.
#7
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The tensioner is on the back or slack side of the belt, so a tensioner moving won't affect the cam position much.
Did you pull the pin from the tensioner, and measure the piston extension per the instructions? Is the extension the same each time you check the cam position?
Were the gears clean?
After all that, drive the car for a while, and check timing again. The new belt may have somewhat fat ribs on it that don't sit down all the way into all the gears. A little driving will get the belt and all the gears working a little more closely together.
Did you pull the pin from the tensioner, and measure the piston extension per the instructions? Is the extension the same each time you check the cam position?
Were the gears clean?
After all that, drive the car for a while, and check timing again. The new belt may have somewhat fat ribs on it that don't sit down all the way into all the gears. A little driving will get the belt and all the gears working a little more closely together.
I am also assuming that the belt is set to at least 5.0
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#10
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Are you measuring at #1 0|T (clamp ring keys pointed up) each time?
After making any adjustments, you should clear the belt and spin the engine with the starter to equalize the belt tension. (You should have done this once already after installing the PKsn'r.)
Factory measurements with a cold engine are 1-4, 2° retard, and 5-8, 0°.
If you are working from a printed copy, then the manual you have may be old. There have been revisions with new tips and tricks. You can always download the most current manual here: http://liftbars.com
After making any adjustments, you should clear the belt and spin the engine with the starter to equalize the belt tension. (You should have done this once already after installing the PKsn'r.)
Factory measurements with a cold engine are 1-4, 2° retard, and 5-8, 0°.
If you are working from a printed copy, then the manual you have may be old. There have been revisions with new tips and tricks. You can always download the most current manual here: http://liftbars.com
#11
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My timing as it stands is 4 degrees retarded on the drivers and 3 degrees retarded on the passenger. I am rotating the engine by hand with the plugs in. I have rotated it about 8 or 10 times so far. Porkensioner extension is 5mm, but I dont check this every time only the final time I measured.
One thing I have noticed is there is a bit more tension,, it seems between the drivers cam and the WP then anywhere else. This is also one of hte shortest passes the belt makes which can make it seem that way, but after 10 or so rotations I would assume the tension is what it will be.
The only adjustment I have made was at 45 BTDC which got things close enough to be rotated to the tdc position. After doing so my drivers cam was spot on but my passenger one was 10 deg retarded, so I set it to zero and turned twice and checked, turned twice again and checked with different result and kept doing this with different results.
One thing I have noticed is there is a bit more tension,, it seems between the drivers cam and the WP then anywhere else. This is also one of hte shortest passes the belt makes which can make it seem that way, but after 10 or so rotations I would assume the tension is what it will be.
The only adjustment I have made was at 45 BTDC which got things close enough to be rotated to the tdc position. After doing so my drivers cam was spot on but my passenger one was 10 deg retarded, so I set it to zero and turned twice and checked, turned twice again and checked with different result and kept doing this with different results.
#12
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The only adjustment I have made was at 45 BTDC which got things close enough to be rotated to the tdc position. After doing so my drivers cam was spot on but my passenger one was 10 deg retarded, so I set it to zero and turned twice and checked, turned twice again and checked with different result and kept doing this with different results.
#13
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It sounds like the main issue is that the engine has not been turned with the starter. This will seat the belt in the gears, pump up the lifters, and equalize the belt tension.
Another tip: with a new belt, set both sides to zero. When the belt stretches during the next few hundred miles, the 1-4 side will end up at ~2° retard.
Also, when adjusting the 1-4 cams, add 2° advance to the setting you want. Because of the reaction of the belt (stretching) against the high spring tension on the 1-4 cams at 0|T #1, the adjustment will be retarded by 2° after you spin the engine. For example, if you want the 1-4 side to be -2°, adjust it to 0. If you want it to be 0, adjust to 2° advance, etc. After spinning the engine, the setting should show the intended setting.
Always recheck the timing at 1000 miles or so after a new belt install if any adjustments were made.
(All these tips are in the current manual.)
Another tip: with a new belt, set both sides to zero. When the belt stretches during the next few hundred miles, the 1-4 side will end up at ~2° retard.
Also, when adjusting the 1-4 cams, add 2° advance to the setting you want. Because of the reaction of the belt (stretching) against the high spring tension on the 1-4 cams at 0|T #1, the adjustment will be retarded by 2° after you spin the engine. For example, if you want the 1-4 side to be -2°, adjust it to 0. If you want it to be 0, adjust to 2° advance, etc. After spinning the engine, the setting should show the intended setting.
Always recheck the timing at 1000 miles or so after a new belt install if any adjustments were made.
(All these tips are in the current manual.)
#14
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I dl'ed your manual off of your site. I had an issue adjusting thaqt I wanted clarification on.
I decided to adjust the current settings both to zero and see where that got me once I cranked it with the starter. I started by setting up the drivers side for adjustment. When I loosened the 32vr ring I was holding the cam bolt with a wrench expecting to fight a backwards resistance and to pull the cam against spring pressure to the zero mark. Instead what I got was the cam flicked foreward un-torquing the cam bolt and stopping agains the ring clamp bolts at the edge of the sprocket adjustment slot. So now it is like 6 degrees advanced and I cannot bring the cam back against the spring pressure without grossly overtorquing the bolt. These adjustments were tried at TDC. How do I retard the cam?
I am confused by the manual. From what I gather I am supposed to tighten the cam bolt down without the spacer so it holds the current advanced timing and rotate the crank to 20 deg after TDC and then loosen the cam bolt and porken ring and turn the crank and hope the cam stays still untill timing is correct. Then tighten things up and turn things over and measure....?
I decided to adjust the current settings both to zero and see where that got me once I cranked it with the starter. I started by setting up the drivers side for adjustment. When I loosened the 32vr ring I was holding the cam bolt with a wrench expecting to fight a backwards resistance and to pull the cam against spring pressure to the zero mark. Instead what I got was the cam flicked foreward un-torquing the cam bolt and stopping agains the ring clamp bolts at the edge of the sprocket adjustment slot. So now it is like 6 degrees advanced and I cannot bring the cam back against the spring pressure without grossly overtorquing the bolt. These adjustments were tried at TDC. How do I retard the cam?
I am confused by the manual. From what I gather I am supposed to tighten the cam bolt down without the spacer so it holds the current advanced timing and rotate the crank to 20 deg after TDC and then loosen the cam bolt and porken ring and turn the crank and hope the cam stays still untill timing is correct. Then tighten things up and turn things over and measure....?
#15
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From what I gather I am supposed to tighten the cam bolt down without the spacer so it holds the current advanced timing and rotate the crank to 20 deg after TDC and then loosen the cam bolt and porken ring and turn the crank and hope the cam stays still untill timing is correct. Then tighten things up and turn things over and measure....?