280ZX Distributor Advance Curve Reference

[doradox]

One of the reasons the later cars could tolerate the high spark advance is EGR. EGR goes a long way towards reducing spark knock as it is used to reduce combustion temperatures below the level that oxygen and nitrogen combine into NOX. EGR is often demonized as just another evil emissions device that robs power and mileage. It allowed more advance under light load conditions so fuel economy could be improved over other methods, low compression and rich mixtures being two, that could be used to reduce chamber temps.

Steve

[Walter Moore]

I've been meaning to get hooked up with the Indy club but life always seems to get in the way. I lived in Lebanon for 8 years before moving out to the sticks about 3 years ago. I'm surprised I never saw your Z.

Steve

Likely you didn't see my car because prior to September 2007 the only people who had were those with access to my garage. I barely got it running in time to enter it in the "Back to the 50's" car show that year.

[Walter Moore]

As I was tearing down and inspecting one of my points distributors I discovered that the "T-bar" is marked 12, meaning that it has a whopping 24 degrees of centrifugal advance. That didn't match anything in my previously posted chart.

I cleaned off the body and found the following marking:

D612-52

Which again wasn't in my chart. After some searching on the internet I discovered that this is the "stock" distributor that came on the L24 equipped 240Z in the U.S. I guess I missed it when I made my initial chart. Interestingly, the Haynes manual also does not list this distributor, and it requires a totally different initial timing setting than all other distributors, 5 DBTC.

(Remind me to burn that Haynes manual soon...)

I have confirmed, using a "dial back" timing light, that the points distributor I have installed on the car matches this advance curve. I also discovered that fortunately the vacuum advance on that distributor is broken, since I have it set to 10 degrees of initial timing.

Anyway, attached is the updated chart.

Distributor advance curves revision 1.xls

[madkaw]

walter,

I was pouring over your excel spreadsheets(very nice work by the way), I wonder what nissan had dizzies on line 16&17. I like those curve numbers, but don't know what the application is. Is all these numbers just for zx dizzies? Mine doesn't show on the chart, I have the d6k8-26, if I remember correctly. The first number match, but my dizzy ends with -26.

Edited September 2, 2010 by madkaw

[Walter Moore]

Steve,

Lines 16 and 17 are for the 1974 U.S. specification 260Z (As indicated by the color code described at the top of the page)

I just copied the numbers out of the factory service manuals for the years indicated. I have no idea how to decode them. As you mentioned the -26 doesn't appear in the chart, but there is a D6K8-22 which was for a 1980 California S120. I suppose that it is possible that the -26 was for a different model Datsun from the same era.

(Perhaps and 810 if it was still around, or the Maxima?)

Some of the people on this site have access to the Nissan parts database. Perhaps one of them will add to the discussion.

[madkaw]

I really like the ignition curve of that dizzy-that's why I am asking. I figured out the chart:stupid: and was excited to see that I actually have one of those dizzies that I inquired about. Now to play!

[Walter Moore]

By the way, I have recently updated the chart to include more specific information on the S30 distributors.

See the attached.

Oh, and by the way Steve, the 74 distributor is meant to be used with a different electronic ignition than the S130 model's E12-80.

I have no information on that model of ignition module.

Distributor advance curves S30-S130.xls

[MY1PATH]

I know this is an old thread but I thought I would add a finding...

My '74 260z auto came with a D6F3-02 But the T-Bar had 14 stamped on it for 28 Degrees of mechanical advance. I think thats a new High and maybe a little scary.

I am currently rebuilding an electronic D6K80-03 out of an '81 280zx (17 degrees advance)

I'm guessing with fuel injection flame fronts moved faster and that's why less mechanical advance was used from '75-83

[George_Zed]

I am sorry to ask a question in an old thread but I need your advice and it suits better here than opening a new thread...

 

I saw the advance curve and I am bit worried... I have a 280zx distributor D6K82-01 which is in the red area...

 

Can I use it but with specific guidelines (specific timing or sth else...) or it is better not to use it at all... ?

 

I have a 73 240z with dual webers, I have the Distributor Mount Plate Base, E12-80 Conversion and I will use the  8202K MSD Blaster 2 Coil...

 

please give me an advice...

[240260280z]

If you do not use the vacuum advance and set initial at 19 degrees then total will be 36 degrees  (19 degrees static and 17 degrees mechanical). This woks nicely for many.  Starting at 19 degrees advance may buck the starter a little.

[George_Zed]

thank you Blue for your reply

 

I need to ask few questions though...

 

1. what do you mean by "buck" the starter? can't find appropriate translation for "buck" 

 

2. I read about few disadvantages when vacuum advance is not used...  "For peak engine performance, fuel mileage, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance" Is the above statement true?

 

Is this the only way to use the distributor I have? Shouldn't be concerned on having a total advance of 36 which is lower than stock (40-43)?

 

Forgive me if I make stupid questions... I am just a noobie with a 240z trying to fix / tune my Z

[240260280z]

All good questions:

1.   With ~20 degree's initial advance, the slow rising piston by the starter (~ 200rpm) will allow the explosion to push back on the piston until the RPM's are at  idle ~ 800rpms when the piston is moving faster.  This makes it more challenging for the starter to crank and you can actually feel it.
 

2. That is true for cruising. Vacuum advance helps with fuel efficiency at cruise.

 

3.  A total advance of ~ 36-38 seems to work nicely with these engines.  You can adjust to your taste.