Question about timing?

[mjr45]

I've been having some problems getting my timing right as I'm sure some of you know from my numerous threads on this issue.. The engine is out of a 79ZX and timing should be 10°. After setting up #1 to TDC with the crank timing mark at 0 and the oil pump key as shown in several pics and the FSM at 11:25, the timing is about 40° and won't retard any further. It appears to me that I will have to change the oil pump shaft to about 12:30 in order to get to the correct timing. The cam and crank timing marks have been checked several times and are correct. I removed the dizzy set screw to move the dizzy CCW to get to 10° and its about 3/8" from the lockdown point of dizzy, so I'm thinking to move the oil pump about 3-5 teeth CCW to try and get close. Anybody had issues like this?

Edited March 20, 2014 by mjr45

[FastWoman]

It sounds like you are looking at the correct solution. Your oil pump was probably installed on the wrong tooth. I worked on that part of my '75 decades ago, but if memory serves, it was a somewhat miserable job. I think it would have been much easier if I had a volunteer top-side to tell me when the shaft was oriented correctly.

[Zed Head]

Sounds like you might just have the plug wires off one hole.

OR

Which distributor are you using and does it have the mounting base that matches? Z and ZX distributors have a different base with holes for the adjusting screws in different spots. If you have a ZX distributor on your 1975 280Z base,or vice-versa, it might cause problems like you're having.

[mjr45]

FastWoman, now that I've done this job 5 or 6 times it gets easier each time.

Edited March 20, 2014 by mjr45

[mjr45]

Zed, its a ZX dizzy with the ZX mounting base. I tried moving the #1 to one hole on each side of the correct spot and couldn't get it to run, well it tried to start once but wouldn't stay running, so I'm thinking it all has to do with the oil pump spindle being off just enough to cause the issue.

Mike

[Zed Head]

Just to tweak your thinking process a little bit - the position of the oil pump shaft only matters in that it allows you the proper range of rotation for the distributor. You could make the timing right by removing the adjustment screws to allow more rotation, setting the damper pulley to zero (or ten degrees before zero), turning the distributor until the teeth on the distributor trigger are aligned, then setting the plug wires so that the rotor is pointed at the #1 spark plug wire. That's what the FSM description is trying to make happen, without going in to all of the details.

IF you do that, it will also give you and idea of how many degrees off the spindle is, or may also show you that one of the plug terminals can be used, by turning the distributor until two different teeth align. A spark happens every time the teeth inside the distributor align. Your job is to get the spark to jump to the correct terminal of the distributor cap.

The basic procedure, in few words, is to set everything up so that a spark happens at ~ten degrees BTDC, then set the spark plug wires to distribute them correctly.

[mjr45]

Zed, that was my next try in the process. It looks like the dizzy is just about 1/2 tooth off, so taking your advice, I'll make anothet attempt tomorrow, after 3 hours of pulling the pump and dizzy, I just gave up. Thanks for the help.

Mike

[mjr45]

OK folks, riddle me this, I did as Zed suggested and lined up the oil pump shaft so that the reluctor teeth in the dizzy were aligned and with #1 at top dead center, the alignment mark on the crank at zero. Stared it up, adjusted timing to 10° (with a light and vacuum gauge) adjusted the idle and thought OK all set, idling nice and smooth sounds great. NOT, took it out for short spin and sputtered and bucked anywhere above 3500 RPM, came back, re-adjusted the timing to 0°, took it out ran great with lost of zip right up to 4500 RPM and then the same thing. WTH?? Can't do anymore work today, its snowing AGAIN and even with my shop heaters going full bore can get to about 30°.

Edited March 22, 2014 by mjr45

[madkaw]

What's the vacuum gauge for? Was the engine fully warmed up and was idle right? What's the timing at 3000rpm?

Have you tried to swap out ignition modules?

Edited March 22, 2014 by madkaw

[mjr45]

Mad, didn't check timing at 3K, the engine was warm, the idle had to be adjusted a couple of times to get it right and the vacuum gauge will help tell you at which point the engine @idle is making the best vacuum and thus running well. You can attach a vacuum gauge and by moving the dizzy, make the vacuum go up or down, its a very old way of checking the engine.

Mike

Edited March 22, 2014 by mjr45

[mjr45]

I had one other thought(these are few far between) that maybe the issue is with fuel and not spark. I've not done the fuel pump lines from the tank to pump and pump to fuel line and maybe they are clogging up or collapsing under load?

[Walter Moore]

Ok, here is a basic question: what is the condition of the distributor? Are you using vacuum advance? If not is the breaker plate locked down to prevent it from moving? What year of ZX distributor do you have? The later ones can have an enormous amount of vacuum advance, and if the breaker plate isn't locked in place it can move and shift your timing by up to 30 degrees. Speaking of the distributor year, the late ignition module retards the timing somewhat. There is a thread on that somewhere....