280ZX Distributor Advance Curve Reference

[George_Zed]

thank you so much Chickenman

 

the information you shared with us is very detailed and helpful!!!

 

I will let you all know when I finish... It is obvious now that I will go for the canister adjustment (decrease to 18) and increase the initial timing...

 

About the initial timing... in order to adjust it to get it to15 degrees... I do this just by changing the distributor's position right? Of course I will have a timing light when doing all these adjustments...

 

sorry for asking, but 15 initial + 17 mechanical + 18 Vacuum = 50 isn't too much? Or I missed something here?

 

oh yes, I missed that total advanc is inital+mechanical (I thought total was all three together... so it will be 32 which is good... and then a 15-20 degrees of vacuum is needed...

[Chickenman]

Yes... Total mechanical advance is initial timing + dizzy mechanical advance. In the example 15 + 17 = 32

 

32 degrees ( example )  is the figure that you check with your Dial Back timing light to get maximum power, with Vacuum advance disconnected.

 

The additional Vacuum advance of approx 15 to 20 degrees is only required and supplied under light throttle, light load and high engine vacuum conditions. That is when the cylinder charge density ( VE ) is very low and the air/fuel mixture needs to be ignited earlier in the combustion cycle to ensure that the burn cycle is completed at the proper time ATDC. As soon as more load and more  throttle opening occurs, the additional vacuum advance will drop off as the cylinder charge desnsity ( VE ) increases.

 

Note: Do not confuse Air/Fuel mixture density ( Cylinder charge density or VE )  with Air/Fuel Ratio. They are two entirely separate things. IE: You could have a 14.7 to 1 AFR ( Stoich ) at 100% VE and a a 14.7 to 1 AFR ( Stoich ) at 50% VE. The 50 % mixture would have to be ignited earlier in the combustion cycle ( Vacuum advance ) because of the slower burning of the flame front. Lower charge density = longer flame front burn time ( given all other factors the same ).

Edited December 5, 2014 by Chickenman

[George_Zed]

Thank you all for your help!!! I will let you know when I install and adjust my distributor

[George_Zed]

ok, I thought I finished with my questions but apparently I am not

with the 280zx distributor and the 8202K MSD Blaster 2 coil (and no ballast resistor), I will probably need to change the spark plugs and plug wires too... right? or it isn't necessary?

I haven't checked which spark plugs and plug wires has the car now, but I read that I should have the NGK BR6ES-11 spark plugs and maybe some NGK plug wires too...or a different make? which plug wires are the best fit for this setup? and am I right to go with spark plugs BR6ES-11 or is it better to choose the BPR6ES-11? From what I read the first one is what most of you use with 280zx distributors... but the weird thing is that in few stores online these spark plugs does not fit our cars...??? And in http://datsunzgarage.com/engine it says the second with the "p"...

edit: I checked a bit online... The NGK Ignition wire set NE61 seems to be ok...

but I need some confirmation from the experts here

[Zed Head]

You'll probably want to gap the plugs wider to take advantage of the high energy ignition module.  So the -11 is the way to go since it's prebent to .040" gap.  P is for projected tip and it's not really clear why Nissan jumped around on that specification.  People have their theories but the shape of the combustion chamber is probably what matters most.  Can't really go wrong using the factory spec.  If your engine used a P tip, use a P tip.  New wires are a good idea since you'll have more voltage with the wider plug gap.

 

It's the -11 that's probably giving you problems on the fitment.  -11 is prebent for the .040" gap.  These would not work with points well but you don't have points any more.

 

I'd use the BPR6ES-11.

[George_Zed]

Thanks a lot Zed Head

[Chickenman]

I worked as a Nissan Partsman from the Mid 70 through the early 1990's. Datsun/Nissan had TSB's ( in Canada at least ) to always use the Projected tip plugs in place of the non projected tip. Places the spark  kernel in a better position to promote flame propagation and also the projected style resists fouling better.

 

As mentioned, BPR6ES-11 is what you want. You could also use their V-Power series. BPR6EY-11

 

The NGK NE61 plug wires are very high quality. Plus they smell like Bubble Gum...Yum!!

Edited December 11, 2014 by Chickenman

[George_Zed]

Thanks Chickenman

[Captain Obvious]

Datsun/Nissan had TSB's ( in Canada at least ) to always use the Projected tip plugs in place of the non projected tip.

 

There was some discussion about projected vs non-projected tipped plugs in the past, including this thread:

 

http://www.classiczcars.com/topic/44600-spark-plugs-projected-tips-vs-standard/

 

And there is continued speculation as to why, in 75, they went away from the projected tip in the first place only to go back to them in 1980. Is there any info about that in the TSB? Have you got a copy?

 

[Zed Head]

I was wondering about the TSB also.  It would be cool to see some official Nissan communications on the subject.  It seems odd to use the standard tip on the dished piston and the projected on the flat.  Just initial gut feel.  They are different heads though, N42 and N47 vs. P79.  But if Nissan realized a problem later on, that would be interesting.

[Chickenman]

Up to about 6 months ago I had all of my Nissan Partsman and Service Tech training tests and info. A lot of TSB's were included in that. Unfortunately, I did a massive clean-up and threw them all out.

 

If I remember correctly, the reason for recommending Projected tip plugs in Canada, if regular tip Plugs were originally specified, was mainly to reduce cold weather fouling in our bitter cold winters. I don't know if USA had similar TSB's. Possibly in some of the more Northern States.

 

The article that was previously discussed mentioned by Captain Obvious is correct. Improved flame propagation and reduced fouling are the Primary reasons for using Projected tip plugs.

[Captain Obvious]

So all indications are that the projected tip plugs are better than the non-projected... Was there any indication as to why they ever went away from the projected tips in the first place?

 

I'm still looking for the downside to the projected tips that made Datsun move away from them for a bunch of years.