90 Z32 timing off, need help
#1
90 Z32 timing off, need help
Hey guys I'm new to the forum and I needed some help with my timing belt. I have my four gears lined up but it seems my crank was off by one tooth. I'm kinda new to and I understand that since it's an interference motor, pistons can hit valves etc. In the service manual it says to align the mark on the harmonic balancer to 15 degrees, does anyone know how to do this? it seems I was like one tooth off the first time i did it.
#2
You're confusing timing belt alignment and ignition timing.
15deg BTDC is the ignition timing (at what point the spark plugs ignite the air/fuel mixture) - it's set by using a timing light aimed at the crank pulley and adjusting the CAS. If your belt is not installed properly, don't even bother with checking this (also, if you never moved the CAS, you shouldn't need to adjust this).
If your belt is off by one tooth, you have to fix that (the timing belt handles the mechanical synchronization of the engine, and it will never run right if the belt isn't installed right). There are marks on the belt and dimples on every gear (all 4 cams and the crank sprocket) and the backing plates (in the case of the crank sprocket, the dimple is on the bottom shield toward the driver's side, if memory serves). Align all the dimples, then, starting with the crank, align the marks on the belt with every dimple. When you get to the intake cams, do not try to loop the belt under the idler pulley while installing the belt - line up the marks first, use clamps (lightly) to hold the belt in place, and then put the belt under the idler pulley.
Once the belt is lined up, THEN you can worry about your ignition timing being at 15deg BTDC.
15deg BTDC is the ignition timing (at what point the spark plugs ignite the air/fuel mixture) - it's set by using a timing light aimed at the crank pulley and adjusting the CAS. If your belt is not installed properly, don't even bother with checking this (also, if you never moved the CAS, you shouldn't need to adjust this).
If your belt is off by one tooth, you have to fix that (the timing belt handles the mechanical synchronization of the engine, and it will never run right if the belt isn't installed right). There are marks on the belt and dimples on every gear (all 4 cams and the crank sprocket) and the backing plates (in the case of the crank sprocket, the dimple is on the bottom shield toward the driver's side, if memory serves). Align all the dimples, then, starting with the crank, align the marks on the belt with every dimple. When you get to the intake cams, do not try to loop the belt under the idler pulley while installing the belt - line up the marks first, use clamps (lightly) to hold the belt in place, and then put the belt under the idler pulley.
Once the belt is lined up, THEN you can worry about your ignition timing being at 15deg BTDC.
#3
Thanks I appreciate the reply, it seems I got it just right. You said I adjust the CAS to align the mark to 15 degrees BTDC. How will I go about doing that? Do I adjust the CAS while the enigne is on or.... please lemma know I appreciate all the help
#4
Well if your timing belt is off a notch, you will NEVER get the ignition timing right, so you have to fix that first.
And you seriously need to do some research - I do not get the impression you are qualified to be working on this car, yet. The engine needs to be running while you aim the timing light (which is basically a strobe light that'll flash in time with cylinder #1's ignition and light up an indicator mark on the crank pulley that'll align with the ignition timing plate, telling you your ignition timing) and adjust the CAS until you're at 15 BTDC.
And you seriously need to do some research - I do not get the impression you are qualified to be working on this car, yet. The engine needs to be running while you aim the timing light (which is basically a strobe light that'll flash in time with cylinder #1's ignition and light up an indicator mark on the crank pulley that'll align with the ignition timing plate, telling you your ignition timing) and adjust the CAS until you're at 15 BTDC.
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