Cam timing - HELP Please
07-04-2012, 03:16 PM
#1
Rennlist Member
Thread Starter
Cam timing - HELP Please
Well, the new year is off to a good start, as I just finished timing the cams. Thanks to Steve Weiner for input and guidance, Wayne's book, and Anthony (Axl911 on Rennlist)
I used Anthony's write up because he condensed it into easy to follow steps. I installed a mechanical lifter on #1 and gapped it to .1mm. I then installed a Z block from Pellican, and installed a digital dial gauge and pre loaded it, then zeroed it. I did not have enough shaft to preload a full 10mm, but figured it was the initial few mm's that were important. When the digital dial is zeroed, it will show the deflection of the intake valve as a negative, which makes sense. I then proceeded to follow these steps...
To set timing for Cylinder 1.
1. Rotate the pulley so Z1 mark is lined up with the case parting line.
2. Install cylinder 1 intake rocker.
3. Make sure both cams have the dots pointed straight UP. Draw a line from the dot through the center of the cam will make it easier to see the dot is pointed straight up.
4. Put the pin into the cam sprocket where the holes line up. Do this for both sides. You can put the cam sprocket bolt in or not. Leaving it out makes it easier to see how the dot moves.
5. Adjust the cylinder #1 intake valve clearance to .1mm like you normally do in valve adjustment.
6. Mount your dial gauge on cylinder #1 intake. And set it to zero value.
7. Rotate the crank pulley clockwise almost 360 degrees. As you approach the Z1 again you will notice the dial begin to move.
8. Continue to rotate clockwise until the gauge moved 1.26mm or .05 inch. STOP.
9. Is the Z1 mark lined up with the case parting line? If not, use a small screw to remove the pin on the left side cam. Rotate the crank pulley until the Z1 mark is lined up with the case parting line.
10. Now put the pin back into the cam sprocket where the holes line up.
11. Double check by rotating the crank pulley 720 degrees. By the time the Z1 comes around for the second time, when the Z1 is lined up with the crank pulley, your dial gauge should have moved 1.26mm or .05 inch.
12. You are done with cylinder #1. Don’t move anything.
13. If it takes more than 360 degrees to get the dial gauge to move 1.26mm, then you either don’t have the cam dot pointed straight up at the beginning or you did not adjust your cylinder 1 valve clearance properly.
I used Anthony's write up because he condensed it into easy to follow steps. I installed a mechanical lifter on #1 and gapped it to .1mm. I then installed a Z block from Pellican, and installed a digital dial gauge and pre loaded it, then zeroed it. I did not have enough shaft to preload a full 10mm, but figured it was the initial few mm's that were important. When the digital dial is zeroed, it will show the deflection of the intake valve as a negative, which makes sense. I then proceeded to follow these steps...
To set timing for Cylinder 1.
1. Rotate the pulley so Z1 mark is lined up with the case parting line.
2. Install cylinder 1 intake rocker.
3. Make sure both cams have the dots pointed straight UP. Draw a line from the dot through the center of the cam will make it easier to see the dot is pointed straight up.
4. Put the pin into the cam sprocket where the holes line up. Do this for both sides. You can put the cam sprocket bolt in or not. Leaving it out makes it easier to see how the dot moves.
5. Adjust the cylinder #1 intake valve clearance to .1mm like you normally do in valve adjustment.
6. Mount your dial gauge on cylinder #1 intake. And set it to zero value.
7. Rotate the crank pulley clockwise almost 360 degrees. As you approach the Z1 again you will notice the dial begin to move.
8. Continue to rotate clockwise until the gauge moved 1.26mm or .05 inch. STOP.
9. Is the Z1 mark lined up with the case parting line? If not, use a small screw to remove the pin on the left side cam. Rotate the crank pulley until the Z1 mark is lined up with the case parting line.
10. Now put the pin back into the cam sprocket where the holes line up.
11. Double check by rotating the crank pulley 720 degrees. By the time the Z1 comes around for the second time, when the Z1 is lined up with the crank pulley, your dial gauge should have moved 1.26mm or .05 inch.
12. You are done with cylinder #1. Don’t move anything.
13. If it takes more than 360 degrees to get the dial gauge to move 1.26mm, then you either don’t have the cam dot pointed straight up at the beginning or you did not adjust your cylinder 1 valve clearance properly.
The issue I have is the following.
I set the cylinder 1 to TDC and the dot on the cam facing up. I put the pin on and rotate the crankshaft until I get the 1.00mm (I am using 1mm instead of the 1.26 used by Emerald). In order to get the 1.0mm reading I have to rotate a bit more than 360 degrees. So, I assume I have to rotate the crank until I get the 1.00mm reading and then take the pin out and put the crank back into TDC for cylinder 1.
The problem I have is that when I take the pin out, the force of te valve spring moves the camshaft and I loose the 1.00mm valve lift.
What am i doing worng? Please HELP!!!
07-04-2012, 05:08 PM
#2
Rennlist Member
Right, because you're measuring the cam timing at this point. That's all.
Rotate another 360 degrees to take the pressure off the rocker. Then move the pin one left or right, depending on where your timing is.
Rotate another 360 degrees, and recheck.
Rinse, repeat, until you've got the desired timing.
Rotate another 360 degrees to take the pressure off the rocker. Then move the pin one left or right, depending on where your timing is.
Rotate another 360 degrees, and recheck.
Rinse, repeat, until you've got the desired timing.
07-04-2012, 09:11 PM
#3
Pro
Hi
I did this for the first time recently and once it is all straight in your head it is actually quite easy. I was confused for a while though. I went for just under 1.1 mm
All the best
Berni
I did this for the first time recently and once it is all straight in your head it is actually quite easy. I was confused for a while though. I went for just under 1.1 mm
All the best
Berni
07-04-2012, 09:45 PM
#4
Rennlist Member
Thread Starter
Right, because you're measuring the cam timing at this point. That's all.
Rotate another 360 degrees to take the pressure off the rocker. Then move the pin one left or right, depending on where your timing is.
Rotate another 360 degrees, and recheck.
Rinse, repeat, until you've got the desired timing.
Rotate another 360 degrees to take the pressure off the rocker. Then move the pin one left or right, depending on where your timing is.
Rotate another 360 degrees, and recheck.
Rinse, repeat, until you've got the desired timing.
07-05-2012, 02:30 PM
#5
Rennlist Member
You are starting at TDC "firing" with both valves closed (Z1 and both cam marks up) and the dial indicator at zero. A complete combustion cycle is 720 degrees or two crankshaft rotations.
You have to preload your dial indicator for at least the full stroke of the cam lift if you want to see the full stroke of the cam operation or at least more than the length of the overlap distance you are looking for
Turning the engine clockwise 360 degrees brings back to TDC Z1 brings you to the end of the first rotation of the cycle to the "valve overlap period" at the end of the exhaust stroke, beginning intake stroke. The intake will start to open has you approach Z1 and the opening value at TDC is what you want. Both intake and exhaust valves are open at this point.
You have to preload your dial indicator for at least the full stroke of the cam lift if you want to see the full stroke of the cam operation or at least more than the length of the overlap distance you are looking for
Turning the engine clockwise 360 degrees brings back to TDC Z1 brings you to the end of the first rotation of the cycle to the "valve overlap period" at the end of the exhaust stroke, beginning intake stroke. The intake will start to open has you approach Z1 and the opening value at TDC is what you want. Both intake and exhaust valves are open at this point.
07-12-2012, 10:08 PM
#6
Rennlist Member
Thread Starter
Thanks Cupcar. I get how that part works, where I am lost is that after turning 360 I don't get the right lift of the valve, so I need to remove the pin in order to move the crank without rotating the cam. But when I am trying to do that, as soon as I remove the pin, the cam rotates due to the force of the valve spring.
What you are saying is that that adjustment has to be done after rotating 720 degrees?
What you are saying is that that adjustment has to be done after rotating 720 degrees?
07-12-2012, 10:24 PM
#7
Instructor
It doesn't matter where the cam is when you move the pin, you just need to do it in a place with reduced force on the valve springs so the cam doesn't move. You then rotate back to the reference position to check the setting. As Ken says above, just decide which way and how much you want to move it, then recheck.
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07-13-2012, 12:04 AM
#8
Rennlist Member
It doesn't matter where the cam is when you move the pin, you just need to do it in a place with reduced force on the valve springs so the cam doesn't move. You then rotate back to the reference position to check the setting. As Ken says above, just decide which way and how much you want to move it, then recheck.
However, if you are working with the old camshaft design with the big nut where the tool turns the camshaft directly, it is possible (with a little help sometimes) to rotate the cam carefully while it is under tension and watch the dial indicator as you rotate the chainwheel and move the pin.
