1977 Cylinder #1 Mystery

[Zed Head]

I just looked at the 77 tune up chapter and can't tell if you have the old style or the new style.  I thought 77 used the ballast resistor but they don't show it there.  Do you have a ballast resistor by the coil?

 

[ckurtz2]

Yes, I have a ballast resistor. I tested it last year, and it looks like it is still in good condition.

[Zed Head]

Looks like 77 already has the high energy ignition.  I always get the change mixed up with the fuel pump control.  77 was kind of a mid-change year, it still has the old AFM pump relay switch, I think.

Posting before I see ckurtz's reply...

Weird!  The FSM says you shouldn't.  Probably a mid-year change.  So, if you're using the FSM tuneup spark plug gap, you'd be using a wide gap on a weak ignition.  What plug gap are you running?  Migth be a small part of your problem.

Either way, the GM module will give more energy and allow the larger gap.

Edited April 7, 2022 by Zed Head

[ckurtz2]

Interesting, I feel like Datsun jipped me on the ignition system then haha. The vin plate says 01/1977 so it is an early 77. Also has the weird sloped rear deck. Here is the ballast resistor.

 

Well I got the BPR6ES so it's pre-gapped to .035. I can almost guarantee that I left that gap on the old plugs which were also the same type. What gap would you recommend then if I am running the weaker type system? Just do like 0.04?

[S30Driver]

The 77 280z plug gap should be ..  .039 to .043     It has the higher powered ignition module.

[ckurtz2]

@S30Driver

So the transistor ignition unit is what was upgraded and the ballast resistor has nothing to do with it? If that's the cause I will definitely change the plug gap then.

[Zed Head]

21 minutes ago, S30Driver said:

The 77 280z plug gap should be ..  .039 to .043     It has the higher powered ignition module.

If his did he should not have the ballast resistor.  That is the quandary.  He said he has the ballast.  If he has something he shouldn't then maybe he doesn't have something that he should.

Post the number of the module.  I think that that will tell you.

[Zed Head]

Doesn't @Captain Obvious have a 77?

[ckurtz2]

Lets settle this. The Number is E12-12A. 7112

Edited April 8, 2022 by ckurtz2

[Captain Obvious]

Yes, I have a 77, and yes, that's a 77 ignition module.

It is my understanding that the 78's don't need a ballast resistor because the ignition module does a better job current limiting and/or dwell control.

[Zed Head]

What about the FSM showing no ballast resistor and larger plug gap?  The 77 FSM seems to show 78 material.  The higher energy comes from electronic current limiting.  The ballast should be unnecessary.

Does the module number match the 1978 module?  Does it have the plug or the terminal board for connecting it?  I looked around the internet and can't find any E12 numbers, only LX.

My basic point is that Nissan did not get everything done in time in 1977.  It looks like they held on to the old style for a while.

Edited April 8, 2022 by Zed Head

[SteveJ]

4 minutes ago, Zed Head said:

What about the FSM showing no ballast resistor and larger plug gap?  The 77 FSM seems to show 78 material.  The higher energy comes from electronic current limiting.  The ballast should be unnecessary.

Does the module number match the 1978 module?

The 77 FSM does show the ballast resistor.