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77 280z Restoration


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On 9/9/2022 at 4:17 PM, Zed Head said:

Implying that they were using current limiting technology like the GM HEI module.

Well it's not simply an implication anymore. I've poked around inside the 78 module enough to determine that they DID incorporate current limiting technology into it. 74-77 did not have current limiting, but 78 did.

I have no doubt the 79-83 matchbox modules incorporated current limiting as well.

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I got my HEI installed today and took the car for a drive.  I rode it pretty hard and it was a hot day today.   The car ran flawlessly, clean acceleration and no engine hesitation anywhere.  I only pushed it to 5,000 rpm because my engine is still very new., but it was perfect up there.  Overall I’m happy.  I also have my Nissan E12-92 unit bolted up a few inches away from the HEI and have almost completed the full wiring setup that will allow me to swap modules very easily and rapidly using no tools.  Hey I’m a pilot I like redundant systems.   We have 3 of just about everything on the jet I fly for work. 
Here are some pics, it took some hole drilling to make all this merry up right and some special totally flat pan mounting screws for the heat sink so the module would sit flush, there wasn’t a lot of room in the heat sink so this was a must.  
Once I finish all the wiring clean up, like the setup coming out of the distributor I’ll test the two modules back to back and provide an honest comparison.   I made a plate that mounts to the distributor that attaches using the same bolt holes the original module attached with.  Then I cut out a notch on the top of that plate and set in there one half (male) of the weatherproof wire connector and then using steel stik I formed a perfect mold of the area where the wires exit the distributor and around the connector.  Now it will be sealed and a clean attach point.  I haven’t totally completed that so expect pics of that tomorrow,

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12 hours ago, Av8ferg said:

the video showing both ignition modules working

Yes, they both work, so you're gonna use one and keep the other for reserve.. funny.. (Please make yourself a note for the glovebox what you must do when you need to switch, in a year or 3 you will never remember what to do to switch to the other system :facepalm:)

What's about that starter at 1:45 min. in your video, i have heard a lot of start-ups but never one like this one!  Something is not right, grinding gears??

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12 hours ago, dutchzcarguy said:

(Please make yourself a note for the glovebox what you must do when you need to switch, in a year or 3 you will never remember what to do to switch to the other system :facepalm:)

I had a similar thought.  Or put some colors/label on the wires and the module pins.

I had a module crap out on me in my garage after some engine work.  Forgot to put two plug wires back on.  So they do fail for various reasons, but so do the originals.  I carried a spare module and the tools need to change it in the car.  I also had a spare ECU behind the seat.  

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That starter is a gear reduction starter from a ZX.  It’s brand new.   It does sound odd but works perfectly.  Spin faster than the stock Z one.  This one is made by AC Delco bought it on Rock Auto

https://www.rockauto.com/en/catalog/nissan,1982,280zx,2.8l+l6,1209350,electrical,starter+motor,4152

I won’t forgot how to swap these modules out.  It’s dummy proof.  

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10 hours ago, Av8ferg said:

That starter is a gear reduction starter from a ZX.  

I thought about that one, and i took a close look at your rpm-meter when you started but could not see any difference..  now i know how that sounds! 🙂  

It's totally different from the normal startersound!

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Not a bad idea, I’ll keep the extra two wires pieces I built in the glove box and a card with the wire setup drawn out  in case I’m drunk and brake down 🤣🤣
 

Today is test day.  I’m going to run the car around and see if I can shake out any more bugs.  Yesterday, I re-torqued the head bolts from the rebuild and about half of them did tighten a bit (set 60 ft lbs), adjusted the valve lash and replaced the spark plugs.  About 9 valves needed to be adjusted.  7 had too much clearance and 2 not enough but all were within .001 of the cold specs.  (my back hurts now from that) 
The old plugs were fine but my local parts store had the NGK (BPR6ES11) in stock for $3 each so I grabbed them, only needed 4 because I had two remaining when I bought the 8 pack last time. Just doing my part to help the economy. 
 

 

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I’m running the stock EFI.   Those plugs have been exposed to all sorts of usually activity with the ignition issues and getting the timing and advance all dialed in.   Hoping they look better next time.  

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Got some camshaft info that may be of interest. Canceled my order w Motorsport and went straight to Schneider cams for a regrind of the stock cam to their equivalent of Motorsport Stage 3 for fuel injected and rocker arm reconditioning. According to Schneider:

- The stock cam is made of better steel then any cam blank you can get in the US

- You should check for cracks in the area of the dowel pin.  This can be caused by not pulling the cam gear off straight 

- The stock rocker arms have a wear surface against the cam that is better then most

- Keeping the valves properly adjusted is important because excess clearance can cause the arm to wobble and increase wear.  The springs on the pivot end are not very effective at preventing this.  

- Stage 3 is the hottest they recommended for a car that will have AC w a manual transmission.  It requires an upgraded fuel injection system (which I’m planning).

From another source I was told the difference between an injected and a carburetor cam grind is the need to maintain adequate vacuum w injected. Not sure why this is so. They both restrict air w throttle plates.  Maybe somebody has a better explanation. 

I really appreciate suppliers that are willing to share knowledge.  

 

 


 

 

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Thank you!  I do wonder though why maintaining vacuum with injection is more critical than carbs.  Maybe the difference is with injection the intake manifold is pretty much wide open except for the throttle plate and carburetors have venturi and such that provide a little restriction and help maintain vacuum?

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I think it has something to do with the way the fuel is metered from the carburetors.  With EFI the air flow is fairly precisely measured and the appropriate amount of fuel is added to balance the air.  With carbs the fuel is pulled up from the float bowls and basically spilled in to the air stream. There are emulsion tubes and other things but still the fuel gets pulled up in to the air stream, more air = more fuel.  If you have pulses of air from a lumpy cam (inconsistent air flow/vacuum) the fuel gets bounced up and down and accuracy/consistency is lost, plus the fuel does not stay well-atomized.  Carbs work best with smooth air flow through them.  EFI averages out the pulses back at the AFM or MAFS so is not as affected by a lumpy cam.

That's my basic understanding.

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19 hours ago, Av8ferg said:

I’m running the stock EFI.

Ofcourse.. STUPID me...  I didn't read it all but have you used some injectorcleaner? Old injectors deliver total different amounts of fuel, i would do some in half a tank of fuel, normally one bottle is for a full tank. put a bottle of injectorcleaner in your fuel. (Unless you have new injectors or already did this ofcourse.)

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Well, these injectors were sent off and refurbished so they should be good.  The guy sent me a report on each on with flow rates.  I sent him 10 and he picked the 6 that were the best.

Now I didn’t have the cold start injector sent off and like mentioned some posts back I need to make sure this one isn’t a bad actor and possibly operating when it shouldn’t.  It’s warm here so I don’t really need it.   

 

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1 hour ago, Av8ferg said:

need to make sure this one isn’t a bad actor and possibly operating when it shouldn’t.

It's 2 screws, easy to take it out the inlet manifold, put it in a glas and see what it does.  Close the hole with tape and start the engine. it's in the serv. man. what it should do exactly but i believe it stops after 10-15 seconds.. i don't know.

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Here’s what seems strange to me - three in a row that are showing the symptom. Could be random chance, but how likely.  So looking at my rust bucket donor car it appears that the fuel rail is a little lower in the back than in the front.  Is it possible some contamination made its way into the back three injectors?  Pretty far out, but I can’t think of anything else that matches the three and three plug situation  

I like the suggestion of pulling the cold start valve and checking operation. I think it’s more likely a continuous dribble than a faulty signal.   Not sure how that would match the three and three situation though. 

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I’ll just pull the electrical connection on the cold start injector and start there. The car seems to idle a little rich by the smell of the exhaust.

News update: Ran the car off the E12-92 module today and wow is the difference remarkable. The car accelerates so much better on the HEI. With the Nissan module it is much slower through the RPMs. That Nissan module might not be good. I’m going to retest with one of my backups.
Right now the engine is singing using the Flame Thrower HEI. Never ran better and after the Valve lash adjustment and new plugs man is the motor sweet!

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The E12-92 has an extra pin that adjusts timing through a temperature switch.  Might be that when you switched to it you inadvertently changed your timing.  I thought that you had an E12-80.  There's not really a good reason for a performance change unless the E12-92 is failing, or something else changed.

p.s. some people say that you have to short the extra pin to ground or run power through to stabilize the timing.  The 280ZX FSM probably shows how it works so it could be figured out.

Really though, you're about ready to just move on from the old Nissan parts.  

I'll just pile a couple more things in here for anyone with an E12-92 in the future.  Notice the idle switch and the thermo switch connected at the "IC".  Somebody with electronical experience might have fun figuring out what Nissan was doing here.

Last, maybe, edit - here's a zcar.com post from way back, with a reference to 240260280's friend Wayne Monteath.  Apparently, it doesn't matter if the extra pins are connected or not but the question would be where your initial timing is when you switched.  https://www.zcar.com/threads/e12-92-or-e12-80.116513/

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Edited by Zed Head
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Okay so here are my test runs today.   I swapped out the Nissan E12-92 for a different one.   Second one ran worse it was also as 92 not 80, third one is an aftermarket one (92) and ran well so the tests were done with that module against the HEI.   Both ran well, but the HEI idles smoother and I feel the acceleration is cleaner or smoother.   See for yourself below.  


 

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It would be useful to know if the initial timing changes.  Apparently the E12-92 retards timing by 8 degrees, but it's not clear exactly when.  Probably when the engine is hot and the throttle at idle.  For emissions.  Retarded is cleaner.  That's how the 280Z systems work, but with two pickups in the distributor.  When the engine is cold the timing is kept advanced at idle to help with idle RPM.  Not super clear how the ECU is involved unless it completes the ground based on engine RPM or some other condition.

Anyway, in your video you can see that idle PRM are lower for the E12 module.  That is what retarded timing will do, cause idle PRM to drop.  So, it might be that for your tests timing is retarded by 8 degrees for the E12-92.  A quick check with a timing light would answer that question.  Then you'd have to decide if you want to figure out how to make the two modules match.

But, the fact that it runs means that it is serving the fail-safe function, to get home if the HEI fails.

p.s. here is the 280Z description for the two pickup distributors.  When the circuit is open timing is retarded.  Which would fit with having the E12-92 pins disconnected.  I think that you'd have to run 12 volts through those extra pins to get the timing advanced to match the HEI module.

Thanks for letting me fill your thread with extra stuff.  An interesting puzzle.

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Edited by Zed Head
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