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1977 280z Restoration


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#1 Datsun_Driver

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Posted 16 November 2017 - 02:52 PM

Hi all,

I'm new to the forum and I need to soak up some Zed knowledge. I purchased a 280z a few years ago and I'm starting the process of restoration now. It's slow going for me. Also, if I've posted this in the wrong section, please let me know. The car has 69k miles on it and it no modifications. It does have a little rust in a few places, and a cheap respray job over the original light metallic blue paint. Right now my goal is to get it back on the road for under 3k (this does not mean 'restored' condition), and drive it occasionally as a second car while I slowly restore it as I am going back to school. I'm tired of paying the storage fees. lol. Well, at the moment I'm working my way through the electrical system and engine. 

Engine has compression as follows: cylinders in order from firewall,  115, 120, 90, 120, 120, 45.

I also just did plugs and wires, a new fuel pump, and a new fuel filter. I did get it to start briefly on starter fluid. I also confirmed it did turn the fuel pump on when the air flow meter was held open with a screw driver. I'm hoping the low compression might just be stuck valves, but we'll see. Anyone with some knowledge to lend on the process of reviving a Z, I would greatly appreciate the input. 



#2 Bleach

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Posted 17 November 2017 - 02:13 PM

Ya, on that low compression cyclinder ... check your valve clearance (cold settings) when the engine is cold. I wouldn't run it long and warm it up. Also, take out that spark plug and put about 1/3 cup of kerosene into the cylinder. Let it set in there for 5-7 days on the piston ring. If the piston ring itself is stuck against the piston, then this may loosen it up a little to meet the cylinder wall and raise compression.

 

If you do this, unplug the coil wire from your distributor. (to turn off spark) Crank the engine over with the starter and that one spark plug removed first. You want to flush out some off that liquid before you do an actual fire up of the engine.

Then plug in the coil wire to the distributor again, put the spark plug back in, and then start it up and let the engine warm up. Run it gentle... low rpm for a while. 

 

Drive it a little for a few days and then check compression again.


Thank you Ted!
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#3 Datsun_Driver

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Posted 18 November 2017 - 12:07 PM

Ya, on that low compression cyclinder ... check your valve clearance (cold settings) when the engine is cold. I wouldn't run it long and warm it up. Also, take out that spark plug and put about 1/3 cup of kerosene into the cylinder. Let it set in there for 5-7 days on the piston ring. If the piston ring itself is stuck against the piston, then this may loosen it up a little to meet the cylinder wall and raise compression.

 

If you do this, unplug the coil wire from your distributor. (to turn off spark) Crank the engine over with the starter and that one spark plug removed first. You want to flush out some off that liquid before you do an actual fire up of the engine.

Then plug in the coil wire to the distributor again, put the spark plug back in, and then start it up and let the engine warm up. Run it gentle... low rpm for a while. 

 

Drive it a little for a few days and then check compression again.

Thanks Bleach,

 

I'll take a look at the valve clearances and see if there's anything off on the 45psi and the 90 psi cylinders. Does anyone think the 90 is a problem or is that pressure still in normal operating range?

It's not running yet, so I can't drive it. I'll try your suggestion about putting kerosene in the cylinder. Hopefully that helps. 

 

 

Is it normal for the fuel pump to not come on when the key is turned to the ready position (right before the 'start' position?) I'm treating it like a problem right now but maybe it's not. Like I said above, I can get the fuel pump to come on when the air flow meter is held open with a screw driver. BUT, if I don't do that, and just turn the key, the pump never comes on. Any idea what could be causing that problem?



#4 Roadster-ka

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Posted 18 November 2017 - 12:28 PM

I believe pump comes on when cranked.

#5 Bleach

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Posted 20 November 2017 - 07:36 AM

90psi is on the lower end of acceptable. Once you get that thing really running and go through several warm up and cool down cycles (and an oil change) you might see the numbers change. Hopefully for the better.

 

The 280Z pump does not come on to prime the system the same as the 280ZX does. The 280Z pump suddenly comes on WHILE cranking. Try this: unplug the little starter wire that activates the starter solenoid. Then get in the car and hold the key in the crank position. The starter won't go but you should hear the pump kick in at that time. This is a good way to test for pump activity. No matter what, that pump should be going WHILE cranking action is going.

 

After that point, the ECU needs power and the AFM flap has to be open slightly (indicating air going into the engine) for the pump to keep going. There is a safely off that will turn the pump off if it detects that the Air Flow Meter is no longer flowing air. (as in, the engine unexpectedly quit)

 

If you don't have kerosene then maybe other penetrating oil might work just as well. PB Blaster as an example. Spray it in there left to right and use it liberally. Then let it soak for days.


Thank you Ted!
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