240Z Distributor Questions

[rcv]

I'm getting close to completion on my first engine rebuild.  I'm trying to set up the timing using the original distributor following Tom Monroe's instructions and I have some questions.  He says:

Quote

Rotate the distributor housing all the way to the left, or counterclockwise. If breaker points are used, check point gap. It should be 0.020 in (0.50mm). Rotate the housing to the right -clockwise- until the points just begin to open.

I must be dense because I just don't get what he's trying to tell me. If the the gap is already 0.5mm when the distributor is rotated all the way CCW, then what should it be when it "just begins to open"? More than 0.5mm or less?  This is my first time setting up a distributor so I'm thoroughly confused.  My points are measuring 0.25mm when the unit is rotated all the way CCW so I'm guessing I should adjust that.

Also, I can actually rotate my rotor around 10 degrees without moving the housing (or crankshaft for that matter). Is that expected, or is my distributor shot?  Here's a video of me messing with it: https://youtu.be/8ve-9dZ30k8

To be honest, I'm terrified of melting my engine with incorrect timing so any advice is appreciated.

Edited May 3, 2020 by rcv

[jonbill]

the check points gap thing is an aside. I.e. check the points gap before you try to set the timing. it's a pre-requisite of setting the timing.

 

to set the points gap, you rotate the distributor until the points are right on top of one of the 6 lobes, the most open point.

 

[rcv]

Thanks, Jon.  So at their most open, the points should be 0.5mm apart?  Once I've got that set, then I should rotate all the way CCW and then CW until the points just barely open?

Also, any thoughts on being able able to rotate my rotor a few degrees by hand without moving the rest of the distributor? Is that normal?

 

 

[Zed Head]

On 5/2/2020 at 10:29 PM, rcv said:

IAlso, I can actually rotate my rotor around 10 degrees without moving the housing (or crankshaft for that matter). Is that expected, or is my distributor shot?  Here's a video of me messing with it: https://youtu.be/8ve-9dZ30k8

To be honest, I'm terrified of melting my engine with incorrect timing so any advice is appreciated.

There is good stuff in the Service Manual.  You should download it and look through the Tune Up chapter and the Engine Electrical chapter.

Timing is set using a timing light.  It's different from setting the gap of the points.

It is normal for the rotor shaft to turn a few degrees.  That is the mechanical advance mechanism working as it should.

[jonbill]

yes, that should get you in the right area. As zedhead says, best to set it with a timing light, once it's running.

having watched your video, I don't think that movement is right. it's normal to have some movement again as ZH says, but the mechanical advance is sprung so it should return when you release it. is there more resistance in one direction than the other?

 

 

[rcv]

@jonbill Nope, the rotor feels pretty much the same twisting CW and CCW, and it just barely springs back when I let it go.  

[Zed Head]

Remove the breaker plate and look at the weights and springs.  Sounds like the springs are gone or broken.

Found a good video.  You don't want to lock yours but he shows how to take one apart.  4 and 6 minutes show the critical parts.

 

[rcv]

Great thanks @Zed Head - I'll inspect it in the next few days and report back.  Hopefully the springs aren't shot, as a quick look at my usual online stores (zcardepot / zcarsource/ MSA) don't show any for sale.

Edited May 4, 2020 by rcv

[Captain Obvious]

Uhhhhhh.... Yeah, that aint right.

If it springs back slightly, I'm guessing that it's rusty cruddy and virtually locked up. I was just messing with one similar a few days ago. Weights and springs had rusted to the pins they are supposed to pivot on. Maybe you threw a spring too, but I bet it's just wear and crud.

The one I was messing with also had wear marks on the sliding components. So now it moves easy, but it's still notch because of the wear.

[rcv]

38 minutes ago, Captain Obvious said:

rusty cruddy and virtually locked up

Sounds about on-par with everything else on the car. I'll pull it apart as soon as I can and hopefully a little PB Blaster and elbow grease will loosen it up.

[Captain Obvious]

Haha! Welcome to old Z ownership!

This is the kind of stuff I was talking about. The weights and springs were very stiff on the posts because of the rusty cruddy:

I cleaned everything up and now it all moves free, but I can't easily do anything about the wear:

[rcv]

@Captain Obvious you definitely lived up to your name, the distributor was filthy on the inside. I was able to clean it up pretty well, and now it snaps back as expected: 

 

 

There are two pieces of bad news though:

1) One of the springs is completely missing.  Nobody seems to have these in stock anywhere. I suppose I could run with just one spring for a while, but it's not ideal.

2) The breaker plate assembly is pretty locked up.  I didn't try pulling it apart, but I give it a 50/50 chance I lose those little bearing balls when I do. I can also buy a "new" one for $50.

So, my question to you veterans is what's your advice?  My immediate goal is to get the car up and running and drivable so I can have a little fun before I start dumping too much (more!) money into it.  Longer term I've been following @jonbill's speeduino progress which looks like a ton of fun, so I'm not too excited about dumping $600 on any of the fancy new distributors (123, Kameari, etc).  Is it worth retrofitting a cardone 280zx unit, or am I better off getting that new breaker plate and running with 1 spring?  I've heard good things about Advanced Distributors rebuilds but I'm betting they're spendy and the lead time is 6-9 weeks which is a bummer.

Edited May 9, 2020 by rcv