I've got an 81 zxt that i'm having some issues with. I rebuilt the motor and have a new turbo and such things, but i'm having trouble getting it in time. From what I've read on the 'net and in the haynes and chilton manuals, the only way to move the timing on this motor is with the crank angle sensor.

I can't seem to find a timing mark on the crank pulley anywhere, so i assumed i was supposed to use one of the 3 spikes on the ring around the pulley. I have it retarded as far as i can get it, but according to the little spike, the timing is still in excess of 30* btdc.

I'm using the computer from an 82 turbo model. Could this be the culprit? I know they used a sensor in the distributor.

 

On the distributor I'm not totally sure. You know they are controlled by the computer and I have heard that the 1981 turbo distributor was unique to '81. then 82-83 turbo had something changed in the dizzy.

Are you absolutly sure the oil pump and oil pump spindle were installed correctly? They have to be lined up perfectly. If you are off one tooth it will knock your ignition timing about 25-30 deg.

 

In 81 the ignition module was only available for that year only. 82-83 shared their module and 79-80 did also. So this probably your problem. Look at your ignition module if it has only one plug its an 81 if it has a second plug for two wires on the side its off of a 82-83

 

We're talking turbo only. There was no 79-80 turbo.

The turbo distributors are completely different than non-turbo. Their advance settings are controled by the ECU. Maybe you should get a 1982-83 turbo distributor to go with the ECU you are using.

 

i swapped the computer with one from an 81, and it didnt help. I'll look at the ignition module and see what's up.

 

ignition module looks identical to the one on my other '81. (yes, i have two) the one i'm working on is a '79 with an '81 turbo motor. The other is an '81 zxt that doesn't run.

I have a few more strange problems...but i have a feeling they are linked to the timing issue.

The engine won't hold steady at 2000 rpm...it'll cut spark or fuel or something until about 1600 and then go back up....it'll keep doing that until you move the throttle one way or the other. That's the only rpm that it'll do it.

when the turbo starts to boost, the motor acts like it's choking then it'll catch and do many other wierd things.

The starter won't start well when it's hot.

i'm very, very confused.

 

If you rebuilt the motor, are you totally sure you put the timing chain on correctly with the marks lined up and the engine at TDC on the compression stroke?

 

i put both shiney links on the respective number one positions. The piston was at top dead center.

 

I got it worked out. There is a timing mark on the crank trigger wheel that's hard to see with the motor in the car.

it still idles funny sometimes, but for the most part it stays around 750rpm