After 11 years of ownership I'm finally getting around to checking the timing on my Z. The timing is managed by the ECU to some degree but since I'll be pulling the oil pump and swapping in an 82 oil pump shaft and distributor I want to get a baseline timing to make sure it's the same after the sawp. Problem is, I can't find the timing mark / notch on the crank pulley. Does anyone know if the timing mark is different on the 81 280zxt since the CAS wheel is also attached to the pulley. Is the mark on the CAS wheel or on the pulley like other years?

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Phil
1981 280zxt - Now in the care my son!
2014 370Z Sports Touring Roadster

Phil, do you have a timing mark reference gauge attached near the edge of either pulley? (It would look like a saw tooth gauge). Where ever that gauge is, that's where the mark should appear each revolution. You want to look for it near the saw teeth as #1 piston hits TDC. You may have to "feel" for the mark with your fingers or thumbnail, then highlight it when you find the notch:



http://forums.hybridz.org/index.php/top ... iming-mark


http://atlanticz.ca/zclub/techtips/timi ... /index.htm

Thanks for taking the time to help research my question Frank. I stumbled on the same two websites myself earlier today. I know where the reference guide is, I cleaned it off and highlighted it with some white paint. I just can't seem to find the mark on the pulley. Nothing seems to flash by under the timing light...

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Phil
1981 280zxt - Now in the care my son!
2014 370Z Sports Touring Roadster

Make sure everything is hooked up correctly. I've had weird things happen when I've hooked up my light after 24+ hrs of no sleep. It gave me the impression everything was 180* out. I also had to unhook my vacuum advance hose, as I recall. My light had settings for 6v, 12v, 4-6-8 cyl. As soon as I set all the parameters correctly, the timing marks danced visibly for me. (It was complicated somewhat by the weird fact that my Z has TWO sets of saw teeth, one on either side of the pulley!)

Then again, might you have marked the wrong "mark" on the pulley? Run your thumbnail around the pulley edge 180* from where you painted your mark, and zee if you find "another" notch hiding there.

I'm certainly no authority on the ZXT cars. You guys have all sorts of electronic control devices on yours which are completely absent on the basic 240Z

I love my basic 240Z.

Paul? Bryan? What might be happening here?

Thanks again Frank. The 280zxt does not have a vacuum advance, the computer handles that. I can not feel any indentations anywhere on the pulley, but I will check my new timing light for the "cyl" setting!!

The 81 280zxt has a toothed wheel attached to the crank pulley which is used by the CAS to determine cam position, the only year they had that setup. I'm wondering if they also moved the timing mark off the pulley and onto this wheel.

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Phil
1981 280zxt - Now in the care my son!
2014 370Z Sports Touring Roadster

Take off the valve cover and pull the #1 spark plug and rotate the engine by hand until the #1 cam lobes are pointed up. Then put a log thin screwdriver or wood dowel down the plug hole so the tip is resting on top of the piston, and hand rotate the motor back and forth until you have found the true top dead center. Then paint or file your own timing mark on the pulley.
It is possible for the pulleys to slip on their hub....they are actually made in three pieces: a metal inner and outer portion with a hard rubber section in the middle to provide harmonic dampening. Over the years they can start to slip so the original timing mark is nowhere near where it should be. If you eventually find the factory timing mark somewhere weird, or if your new timing mark goes off after you run the motor, you should replace the pulley. On rare occasions they have been known to fail so dramatically that they damage the keyway on the crank snout, which is definitely something you don't want to experience.
Th procedure for finding true TDC with the screwdriver takes a little practice. If you are careful doing it you will find that the point of rotation where the screwdriver reaches the top of its travel is not a perfect single point. If you rotate the engine in one direction and stop as the driver reaches its high spot, then repeat the procedure but rotating towards TDC from the other direction, you will find that there are two rotational points where the piston reaches TDC. The separation of these two points is very small, and as you rotate the engine between them the piston will remain at TDC. You want to mark TDC as being right in the middle of this rotational range. This job can be performed more easily if you have a dial indicator setup that you can install to take readings off the top of the piston, but for your purposes doing it carefully just by hand and eye will be plenty accurate enough. The dial indicator setup is really only essential for the more finicky task of degreeing a cam....

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71 on a rotisserie, two more in pieces in my shed...and a 69 1600 waiting for me to get to it

"...On rare occasions they have been known to fail so dramatically that they damage the keyway on the crank snout, which is definitely something you don't want to experience.."

Yeah ~ ask Phrog.

Thought I'd report that the elusive 1981 280zxt timing mark has been found and marked for future reference! As I expected, the location is different on the 81 turbo model then other model Z's because that one year model has a CAS wheel rather then a solid disk on the crank. The teeth on the CAS wheel are read by a sensor bolted to the block. In 82, the CAS was moved into the distributor.

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Phil
1981 280zxt - Now in the care my son!
2014 370Z Sports Touring Roadster

Eureka!

Well, wonder of wonders! How'd you find it?

I removed the distributor cap and bumped the starter until the rotor was pointing to the #1 plug. This placed the missing timing mark close enough to the reference plate so I could see it from under the car.

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Phil
1981 280zxt - Now in the care my son!
2014 370Z Sports Touring Roadster

Phil, you're smarter than you look.

Frank you're funnier than you look!

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71 on a rotisserie, two more in pieces in my shed...and a 69 1600 waiting for me to get to it

(Others might disagree!)