desertdatsuns.net

Randy,

You are right, the carbs are not balanced at all - neither at idle nor as the throttle opens. I started to fool around with it, got sidetracked when SWMBO showed up with a Gin/Tonic and that was that .

And you are also right - as I mentioned above, the vacuum advance is not working. From what I've read, the ball bearings get worn out and for some reason it's not something that is easy to fix. I understand that the vacuum advance is there to advance timing while accelerating rapidly, and I'd like to get it working, but it seems some guys are happy running with it disconnected. I'll be interested in any/all comments on this.

BTW, I have done the GM HEI Upgrade. I used a Pertronix HEI III, which claims that it "Adjusts spark timing at higher RPMs to compensate for the inherent electronic delay". I know this won't compensate for the malfunctioning vacuum advance, just mentioning it.

I can't speak specifically to the Z, but In most cases the vacuum advance increases timing at cruise. You loose that advance under acceleration to prevent detonation.

Specific to the 280, I have always liked to run 12 degrees initial timing to provide better torque and throttle response. To do this you need to limit centrifugal advance to about half what stock is. I like to limit total advance to about 36 degrees. High initial timing makes NOX emission go up, that is why Nissan has it so low. So this mod is for racing applications only

Thanks to Randalla for the carb tuning help and other stuff this weekend, and to Doc for the telephone-based valve clearance adjustment tutorial. With all of that done, the Z is running rather well: idles around 850-900 RPM, initial timing is around 12 degrees and at 2500 RPM is at 36. There's a little smoke (maybe related to running a bit rich), but I'll worry about that later (if ever).

Next issue is with the clutch/transmission. I swapped the 4 speed that came with the car for a freshly rebuilt close-ratio 5 speed. I used the clutch that was in the car when I bought it, along with the release bearing collar, but I'm pretty sure I installed a new release bearing. By double-clutching I'm able to get it into 1st gear with the car running, and I'm able to shift into 2-5 okay. But shifting into reverse is impossible. We messed around a bit with adjusting the play in the clutch pedal, which didn't seem to have any effect. The clutch had recently been bled, but I checked that as well and it seems okay.

Another (probably related) issue is that there is an unwelcome "heavy rattle" or mechanical noise coming from the back part of the engine / front of the transmission. The rattle changes frequency with engine speed, and it become slightly "louder" if, for example, with the clutch in and the transmission in neutral I pull gently on the stick (as if putting it in 2nd).

The consensus is that the release bearing collar is mismatched with the clutch pressure plate. Come to think of it ... I *think* I used the clutch fork from the 5 speed, but in one of the threads below it's stated that I should have used my original fork. Hmmm.

https://www.classiczcars.com/forums/top ... e-bearing/
https://www.classiczcars.com/forums/top ... ed-please/
https://www.classiczcars.com/forums/top ... 2#comments
https://www.classiczcars.com/forums/top ... n-5-speed/
https://www.classiczcars.com/forums/top ... peed-info/

I don't really think there's a difference in forks for the "B" and "C" transmission models. But I've always just used the fork that came with the transmission.

IMO you need to fit the proper collar. I've had this problem any number of times. The collar needs to match the depth of the pressure plate you installed and has nothing to do with the transmission type.

The collar needs to match the depth of the pressure plate you installed and has nothing to do with the transmission type. (ya, I typed it twice...)

Relatively simple test:
Lift the car and push the end of the fork as far as you can towards the back of the car (that's the throw-out bearing in full contact with the pressure plate). Now, try to push it forward (pressing the rod into the slave cylinder). If it moves forward more than 1/16" or so, you have the wrong collar.

If it's tight then you have air or one of your cylinders is bad. There's only one seal in the slave cylinder so if it's bad, the slave cylinder is leaking. The first place it leaks is into the boot. You can pull the boot slightly loose on the slave and check for fluid. The master could be bypassing internally or leaking out the back (which is inside the cabin).

My first guess would always be wrong collar because I've had that issue myself more times than I'd like to admit...

Thanks, Chuck, for the "relatively simple test". The car is already in the air, so I'll try it tonight.

I remember reading some/all of the posts in the links I included above before I put the transmission on the engine, and it was clear that I needed to use the collar that was with the clutch that I reinstalled. But, I've done stoopid shite before, and the "rattle" I mentioned really sounds like something's not right in the driveline.

I took a quick look through my discarded (but not yet thrown away) parts and didn't see another collar. I'm sure I had two (one from each transmission), and I'm also sure I didn't throw it away, so it has to be here somewhere.

If I decided to just buy a new clutch (since I'm probably taking the transmission out anyway), shouldn't I be able to get the right collar along with it?

Ahh the old reverse issue with a 5speed try putting it into first or some other gear then go into reverse it’s probably worn synchros mine sometimes has issues going into reverse also. Could also be when the trans fluid is still cold you have that issue. Also make sure your not moving at all before you try to go into reverse

The rattle.. could you possibly have the Ryan rattle it’s all too famous around here lol. when I changed my transmission it was making crazy noises even had doc come over to listen it was at the back of the motor front of the transmission .. turns out I didn’t torque my flywheel bolts down properly and it was rattling around.. and when I say didn’t torque I mean they were finger tight at best...

Ryanotown22 wrote: ↑Wed Mar 11, 2020 10:04 am ... and when I say didn’t torque I mean they were finger tight at best...

pogden wrote: ↑Tue Mar 10, 2020 3:29 pm If I decided to just buy a new clutch (since I'm probably taking the transmission out anyway), shouldn't I be able to get the right collar along with it?

I've never seen a clutch kit with a collar in it - but that doesn't necessarily mean anything... They do usually come with a new throw-out bearing.

Just looked on e-bay and there is actually a kit that includes the "sleeve - clutch release" already attached to the "bearing - clutch release". SO, you can!

You need to buy the package for the car that your transmission came out of - 1982-1983 280ZX (non-turbo).

Ryanotown22 wrote: ↑Wed Mar 11, 2020 10:01 am Ahh the old reverse issue with a 5speed try putting it into first or some other gear then go into reverse it’s probably worn synchros mine sometimes has issues going into reverse also. Could also be when the trans fluid is still cold you have that issue. Also make sure your not moving at all before you try to go into reverse

Even though the transmission has been freshly rebuilt (a few years but zero miles ago) and recently filled with Redline MT-90, this does make me want to carefully fool around with it a little more before removing it.