280ZX Distributor Advance Curve Reference

[Chickenman]

I can't figure it out myself, since even back in the mid-seventies Projected Tips were pretty much known to be superior in anti-fouling and combustion chamber position.

 

Maybe Datsun got a smokin' deal on non-projected plugs from NGK? I'm only half kidding there. Nissan bought spark plugs from NGK by the Millions. You save a few pennies here and there and it all adds up for a manufacturer when you're talking those numbers. Datsun/Nissan has  never used anything but NGK.

 

The only reason for using a non-projected tip would be in engines with minimal piston to spark plug clearance. That means High Dome pistons, and that was not an issue on any Nissan motor.

 

I wouldn't lose any sleep over it

 

Edit: The only other thing that occurred to me is the Fuel crisis and EPA in the mid seventies. Mid seventies cars were terribly inefficient due to EPA emissions restrictions...then fuel prices went astronomic ( by 1970's standards ) . EPA standards were just getting into full swing and cars ran terribly lean back then with retarded ignition timing and lowered compression ratios. The retarded timing and lean mixtures would raise combustion temperatures dramatically and may have exceeded maximum temperature range for Projected tip plugs. A regular tip plug has a much shorter insulator, so it could handle more heat. I'm thinking that using non-projected tip plugs may have been a " Half Step " in plug heat range. So a BPR7ES would be too cold compared to a BPR6ES. So use a " half Step" like a BP6ES. Just my own theory.. no data ( Yet ) to back it up.

 

 

Catalytic convertors first started appearing around 1977. Cats allowed the manufacturers to operate the engines much more efficiently, with more advanced Ignition Timing( IE: Normal ignition timing ) , fuel mixtures that weren't so lean that you risked melting pistons and exhasut valves. Compression ratios also went up, increasing the efficiency of the engines back to pre-EPA standards, but with lowered emissions. A think that's a plausible explanation...

Edited December 12, 2014 by Chickenman

[Chickenman]

The more I think about it, the more I believe that emissions standards, with lean mixtures with retarded timing, forced some manufacturers to pull the spark plug tip out of the most efficient area for ignition and closer to the combustion chamber wall where the mixture burns cooler.

 

Ground and center Electrode tip materials back in the day may not have been able to handle the heat. Pulling the electrode tip to a cooler location in the combustion chamber may have been a temporary solution in the transitional periods between Catalytic convertor development and the new Fuel injection systems. These weren't perfected over night by any means.

[Captain Obvious]

Thanks for the input. I put the "correct" non-projected plugs in my 280 (because that's the kind of guy I am) and I've just always wondered if I'm leaving any performance on the table by not running the projected tips like most of the other years.

 

My car does not run lean and  I'm in no danger of overheating my plugs. In fact, I think it could stand to run a little leaner. Something that I've been meaning to look into for a while but hasn't bubbled to the top of the priority list.
 

[rcb280z]

Good thing you dont live in CA Capt or where the smog laws are ruff. You'd be forced to look at rich running conditions.

[Captain Obvious]

Yeah, I know. I've been meaning to take a look at it, but the real way I planned to fix it was to drop in a 280ZX motor instead. I keep putting it off because (in theory) the motor that's in my car currently won't be there for very much longer.

 

In theory...
 

[rcb280z]

Why a ZX motor?

[Captain Obvious]

Why a ZX motor? Because "they" say that the later ZX motors are a little better than the previous years. Basically, I turned up a running ZX motor that has the P79 head with the F54 block and the flat top pistons. A combo which is desirable.

 

I figured that if I was going to be swapping motors, I may as well try to find one of those. So about a year ago I bought an 83 280ZX for the motor and it's been sitting in the driveway since. I haven't yet had the proper opportunity yet to move the motor over to my 77. It's on the list for this off season.

 

So at this point, the short answer is... Because that's what I have? 

[rcb280z]

Hmm.....was hoping that was what you were going to say. I have been looking for a 81-83 ZX motor as well for the same reason. My motor in my 77 is getting worn out and rather than dropping money into it I want a "better" motor. If I have to drop money into the ZX that would be okay because I think its a better way to go. And when I say "drop money" into it just means a few hundred not thousands. It's a D.D. so I need it to be dependable. Wish I had one sitting in my driveway. 

[Zed Head]

I think that the differences between the two engines might be very small.  The change in HP calculation methods really confused any comparisons.  But if you look at the specs, it seems like the old style engines should actually have the power edge.  The cam specs are a hair better for the N42/N42 engines.  The CR is a hair higher for the later ZX engines.  8.8 vs. 83.  The intake manifold is smaller on the ZX engines, and so is the throttle body.  The cam specs for the old engine should produce more power.

 

Really hard to tell, but it's probably just a few HP either way, with maybe a different shape to the power curves.

 

I have a spare 1981 ZX engine in my garage myself.  I bought it because it was in good shape, the price was right, and I thought that it might be a little "better",  But after digging in to the details I can't find the better part.  Seems a wash.  On the other hand, the later ZX's ECU and EFI system could offer potential for a small investment of time.  Probably has a more developed fueling algorithm, and it has an O2 sensor feedback for efficiency.

 

Tried to cobble/copy the specs in for 76 v 82.  Intake open duration is 8 degrees longer, and stays open 8 degrees later for 1976.  Which should allow more charge to enter.  But the lifts are the same, I believe, although I can't find the numbers in the 1982 manual.

 

76 on the bottom.

 

There might be other changes in the F54 block it self that make it more desirable.

[Captain Obvious]

My motor in my 77 is getting worn out and rather than dropping money into it I want a "better" motor.

Yeah, that sounds like the same boat I'm in. The motor currently in my Z works fine but it needs some attention. I figure that attention would be better spent on a later ZX motor.

 

Zed Head, When I first got the ZX, I was thinking I would strip down both motors and redress the 83 as my 77. But the more I think about it, the more I've been leaning towards porting it over verbatim with the whole newer FI system for all the reasons you mentioned.

[George_Zed]

hello my Z-friends

 

I emailed advanceautoparts.com about the ngk spark plugs I want (BPR6ES-11) but they are not made in Japan...they are made in U.S.

 

I have seen somewhere an advice not to buy the made in France ngk... what about those made in U.S.?

 

Anyway, I ordered spark plugs made in Japan that I found in Greece but they are expensive... €3,44 per item...which is $4.22 per item... double the price than advanceautoparts.com sells them...

 

I want to order now the NE61 spark plugs wires... should I look again the ones made in Japan or it isn't necessary? Advanceautoparts.com sells them for only $30... should I buy from there or not? I guess these are also made in U.S.

[240260280z]

Made in Japan parts and parts from Japanese mfgrs are usually the best for our cars.  

 

NGK Spark plugs's plant location  should not matter as the Japanese parent company's standards would be followed in all NGK plants.

 

It is like buying a Toyota car made in the USA..... good quality and possibly better that Japan.