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so having trouble setting timing belt. when i set my cams and crank to marks the LH cam wants to turn clockwise one tooth when i put the belt on. i counted 40 teeth between cam marks and 43 teeth from LH cam to crank. when i put the belt on the crank sprocket with the marked tooth in the gap right after 43 rubber tooth on the belt the LH cam turns one tooth clockwise. if i try to turn the crank counter clockwise to compensate it puts TDC at 5* instead of 0*. i guess its possible my crank pulley has spun slightly. when i pull sparkplug on cylinder 1 and watch the piston come up as i turn crank 0* puts piston at TDC.
heres a youtube vid of the issue: http: http://youtu.be/bq7vv73itgQ[/video]] -
Your cams will have a tendency to spin a little with your rockers bolted down, hard to see, did you loosen them?
As long as your crank sprocket and pulley have clean keyways and woodruffs, they shouldn't move off axis, so the timing marks will be correct -
If all the marks line up for TDC, crank and cams, set the belt onto the crank at the correct position, then slip the belt on the right cam with the belt mark lined up properly. Now with a wrench on the left cam move the sprocket until the belt and cam line up with the final belt mark. Two people make this a lot easier to move both into position. Make sure the tensioner is not adding any tension.
Most of the time you need to hold both cams in place with 2 wrench so they don't roll as you getting the belt on. I have also been able to set the belt without the tensioner in place, then slip the tensioner over the stud with the belt in place. This process can be a pain in the ass. -
ok so my rockers are loosened bc i felt there was possibility for bent valves if anything spun out of sync. the keyways look fine on all 3. i swapped cam sprockets from other motor bc the originals had significant dents in keyways from the cam.
i will try putting the belt on clockwise from top to bottom i assume it would help to have rockers tightened down as well. i might tighten RH rockers first then apply belt then tighten LH rockers. i figure if i pull any on the belt to stretch onto LH then RH will be less likely to move. i usually leave tensioner off until last minute. -
FSM states that the valve covers are to be removed and rocker shafts are to be loosened, allowing, safe, free spin of the camshafts.
Also, when aligning the timing marks, compensate for belt tension. Otherwise, when you go to tighten the tensioner the timing will be off by a tooth or two on the cams. When I did the timing belt on my Z, I set both cams back by one tooth, installed the belt, and tightened the tensioner and as the belt reached proper tension, the marks were just about dead on. (I'll be honest, it took a couple tries to get timing just right.)
Also make sure you get the belt seated properly across the cams or your timing and belt tension will never be right. -
i thought about just setting the "problem cam" back one tooth just havent had a chance to work on it since last time but i figured loosening the rockers couldnt be a bad idea. i feel like years ago when i first did the timing belt i remember the cams spinning out of control from spring pressure. id be afraid id bend a vale from that too. -
Maybe I'm confused, but if your belt is off one tooth, isn't timing set improperly? I just had rockers loosened. got the marks on the cam gear as close to the timing belt plate cover and threw on the belt marked up with the lines on the belt with the dimple on the cam gears/crank sprocket. the cam gears didn't perfectly match up with the marks on the timing cover, but they were close enough and i had 40/43 teeth in between and the lines on the belt matched up fine with all the gear dimples.Twisted`Z;348665 wrote: FSM states that the valve covers are to be removed and rocker shafts are to be loosened, allowing, safe, free spin of the camshafts.
Also, when aligning the timing marks, compensate for belt tension. Otherwise, when you go to tighten the tensioner the timing will be off by a tooth or two on the cams. When I did the timing belt on my Z, I set both cams back by one tooth, installed the belt, and tightened the tensioner and as the belt reached proper tension, the marks were just about dead on. (I'll be honest, it took a couple tries to get timing just right.)
Also make sure you get the belt seated properly across the cams or your timing and belt tension will never be right.Usual Z31 suspect: Garage Queen (aka broken)
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i see what youre saying as far as the markings on timing cover being a "guide". now if i cant get the belt to go on properly with cams and crank at marks then i set back the amount im off. that way when i put the belt on and it moves everything it "should" pull all into correct position. this is all assuming i live in Z eutopia lol.300zxturboftw;348780 wrote: Maybe I'm confused, but if your belt is off one tooth, isn't timing set improperly? I just had rockers loosened. got the marks on the cam gear as close to the timing belt plate cover and threw on the belt marked up with the lines on the belt with the dimple on the cam gears/crank sprocket. the cam gears didn't perfectly match up with the marks on the timing cover, but they were close enough and i had 40/43 teeth in between and the lines on the belt matched up fine with all the gear dimples.
i suppose that the crank markings lining up would be most important. the cams have possibility of flex due to cover bending. the crank marking is stationary.
another question would be that for TDC on COMPRESSION stroke wouldnt the lack of tension on the cam and the fact im setting it on mark force it into said stroke? one turn of cam sproket makes one rotation of cam lobe right? -
Well you don't set the belt on there one tooth off. With the rockers loosened, you would turn the cams clockwise by about a tooth (or however much it takes), put on the belt normally so that the belt markings match with the cam/crank gear markings. (Not the timing cover markings.) Then as you bring the belt to proper tension, it rotates the cams counter clockwise (crankshaft shouldn't move) and the marks on the belt and cams should line up with the marks on the timing cover. That's how I did it, the first time when I had installed the new belt I couldn't quite get the cams to line up just right and the car ran okay but had a power surge at 3500 rpms. After I re-timed the motor using the method I just mentioned, the car ran better, moar power through out the gears and large v-tech-like power surge at 3500 rpms was gone. Car even sounds better. It took me a couple tries as well to find the right spot for the cams before putting on and tightening the belt.300zxturboftw;348780 wrote: Maybe I'm confused, but if your belt is off one tooth, isn't timing set improperly? I just had rockers loosened. got the marks on the cam gear as close to the timing belt plate cover and threw on the belt marked up with the lines on the belt with the dimple on the cam gears/crank sprocket. the cam gears didn't perfectly match up with the marks on the timing cover, but they were close enough and i had 40/43 teeth in between and the lines on the belt matched up fine with all the gear dimples. -
You should have the rockers loosened in the first place. It's bad to try to rotate the cams separately from the rest of the system with the rocker arms still applying pressure. If you loosen the rocker arms you can freely spin the camshafts by hand, and there is no chance of the cam snapping out of position and possibly bending a valve.xanmanz31;348839 wrote: another question would be that for TDC on COMPRESSION stroke wouldnt the lack of tension on the cam and the fact im setting it on mark force it into said stroke? one turn of cam sproket makes one rotation of cam lobe right?
As long as the crankshaft position is lined up properly, and the cams are lined up properly in correspondence to their TDC markings when the belt is at proper tension you've got it. At a proper TDC all 3 gear markings and belt markings obviously line up, and the distributor rotor should point in the general direction of the fuel pressure regulator on the front of the plenum, or more appropriately the rotor should be dead center over the #1 spark plug contact point inside the distributor cap. -
my issue is that its pulling only the LH cam clockwise when i put belt on with tensioner loose. then when i tighten tension it will pull counterclockwise slightly but not enough to bring back to mark.Twisted`Z;349130 wrote: Well you don't set the belt on there one tooth off. With the rockers loosened, you would turn the cams clockwise by about a tooth (or however much it takes), put on the belt normally so that the belt markings match with the cam/crank gear markings. (Not the timing cover markings.) Then as you bring the belt to proper tension, it rotates the cams counter clockwise (crankshaft shouldn't move) and the marks on the belt and cams should line up with the marks on the timing cover. That's how I did it, the first time when I had installed the new belt I couldn't quite get the cams to line up just right and the car ran okay but had a power surge at 3500 rpms. After I re-timed the motor using the method I just mentioned, the car ran better, moar power through out the gears and large v-tech-like power surge at 3500 rpms was gone. Car even sounds better. It took me a couple tries as well to find the right spot for the cams before putting on and tightening the belt.
http://youtu.be/kbXqMh_ij84[/video]] -
count teeth between the cams and ds cam to crank. If they come out to the numbers listed before in this thread then your good to go. be sure to make 2 full revolutions of the crank to ensure no valve contact, then start it. The marks on the back plate are about worthless.Hmmm, Whats next?
Full Size Bronco, smashing shit.
84ZXT -
yeah ive counted the teeth multiple times. i even marked each tooth with white paint pen to make sure. i also went ahead and flipped the belt so the arrows are facing outward. im trying to get things back together so i can start it. im really not sure what else to do. i know the cam sprockets dont have any play since i replaced the original ones for that reason. all rocker shafts are torqued to spec in multiple stages. i set the crank according to punch on oil pump and gear. i also checked that piston was at top with a straightened coat hanger in plug hole waited for it to reach peak.shromy;349250 wrote: count teeth between the cams and ds cam to crank. If they come out to the numbers listed before in this thread then your good to go. be sure to make 2 full revolutions of the crank to ensure no valve contact, then start it. The marks on the back plate are about worthless.
most frustrating part is its jut the LH cam everything else lines up as it should. -
No longer understand your issue , but line up the punch marks with the belt lines install with everything bet cams and crank , count teeth to assure position, then tension the belt per FSM. Cams can be moved to line up the belt to TDC. I wouldn't roll them 180 deg to do that but to move them back or forward a couple teeth is not an issue -
my issue is that my marks arent lining up. they are very close but i worry that ill have to do it again. ive set it as close as i can feel to exact. my tooth counts are good from cam to cam and from LH to crank. guess all i can do now is wrap it up and cross my fingers. biggest pain is not being able to look at crank marks straight on and using the camera doesnt do well either. as for belt tension i dont have a fish scale or anything to test weight i can push it down in the center and it will go down about 1/4 inch.visco;349278 wrote: No longer understand your issue , but line up the punch marks with the belt lines install with everything bet cams and crank , count teeth to assure position, then tension the belt per FSM. Cams can be moved to line up the belt to TDC. I wouldn't roll them 180 deg to do that but to move them back or forward a couple teeth is not an issue
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