running lean '76 280z

[Yarb]

Check CarPartsManual for the p/n and go on line to see if there’s availability through Nissan

[darom]

Thanks for the resource! Found the part number, 14035-N3500, gasket manifold, looks like it is available. Will order/replace it once I confirm the leaks in that area.

[Dave WM]

no double stack they are pretty thick, if it takes more then there is something wrong. I dont know if there is any real preference, the one I used was a felpro, seemed kind of wimpy to me, more like thick cardboard, so you may want to try a different brand than that. IF nissan has them I would go OE.

[Yarb]

 I did a quick check here in the US. No availability but 3 Canadian dealerships did not say unavailable . You might get lucky or check Amayama in Japan.

[darom]

Thanks Yarb, for looking it up.

Just in case I ordered a gasket, Mahle MS16717 (composite) from rockauto. I found a forum chat in the Help Me section where a 280z owner compared it to the OEM from Nissan, they looked identical (with the exception of the price). The plan is to do a valve adjustment as well.

[darom]

Hi guys,

I ran the smoke tests, found a few areas:

1. valve cover gasket, firewall side - big leak.

2. electric EGR solenoid (leaks inside, not vacuum hose), EGR valve (inside again, not the vacuum line). little leak.

3. oil pan gasket - medium leak here.

4. oil dipstick - little leak.

I replaced the valve cover gasket with a cork one, it still leaked. The valve cover/cylinder head appear to be flat. I ordered a silicone one from Milkfab Engineering ($28), the new gasket sealed all the leaks. I made a delete metal plate for the EGR. Replaced all the old spark plugs with new NGKs, replaced the fuel filter. The aux air regulator was replaced with a 300zx unit, which was adjusted to shut. It takes about 6 minutes.

The valves were adjusted. The car's ignition timing is set at 15 bdtc, idles at about 900 rpm. The vacuum is at 17. The car has a strong pull, no hesitation while accelerating.

 

Observations:

1. I think once I replace the oil pan gasket, I might get another 1-2 of vacuum. This is a spring project (it is too cold in the garage).

2. The resistance pod is at 2k Ohms. I still can't kill the engine maxing it out at 5k.

3. The 'new' AAR is unpredictable. If I leave it alone, it will close (not completely) after 6 minutes. Two different days while testing - one day the idle is at 900-950 rpms, today it was at 800 rpms after warm-up. I feel the AAR shutter 'curtain' doesn't guarantee the same closure.

I would like to replace it with a similar mechanical device (like the 240z choke inside). Does anyone know of a part that might work? This way I will open it up when the engine is cold, and close it when it warms up. Once closed, I can set the ideal 850 rpm at idle.

4. When the engine is cold, within those 5-6 minutes of warm-up period, if at idle once rev'ed up, the engine will pop through intake.

5. I still can't kill the engine with the idle adjustment screw. Hopefully, it is the oil pan gasket leak that causes it.

 

Edited November 20, 2023 by darom

[darom]

Some ideas for an AAR 🙂 Manually operating heater valve: https://www.amazon.com/Universal-Conditioner-HV-2211C-Control/dp/B003R31YVQ/ref=m_crc_dp_lf_d_t1_sccl_3_3/138-5872620-2836123?pd_rd_w=UzJvp&content-id=amzn1.sym.76a0b561-a7b4-41dc-9467-a85a2fa27c1c&pf_rd_p=76a0b561-a7b4-41dc-9467-a85a2fa27c1c&pf_rd_r=34220AX20P78YFH9FKCE&pd_rd_wg=aMQD8&pd_rd_r=2ead7de1-3b51-42e0-b3bf-74fcaef91ae1&pd_rd_i=B003R31YVQ&psc=1

or this with the timer relay (I use a cheap timer relay for my injector rail blower/fan from a later model): https://www.amazon.com/4inch-Normally-Closed-Electric-Solenoid/dp/B074Z5SDG3/ref=sr_1_31?crid=3G17GRQMH50IC&keywords=solenoid+valve+1%2F2in+12V&qid=1700513498&sprefix=solenoid+valve+1%2F2in+12v%2Caps%2C84&sr=8-31

Edited November 20, 2023 by darom

[Yarb]

IMO no. Ned to find an AAR that works correctly.

[Zed Head]

A ball valve with a cable would work.  It would be, in essence, an idle speed control.  

https://www.homedepot.com/p/Apollo-3-4-in-Brass-Insert-Poly-Ball-Valve-POLYV34/300850934

[zKars]

Or go all the way with a Vintage Air servo controlled heater control valve and adjust idle with a dial on the dash!

https://www.vintageair.com/custom/product-pop.php?pn=50507-VUA

[darom]

Thanks for the ideas!

I might be building a simple on/off solenoid with a cheap time relay board set for 2-3 minutes: https://www.amazon.com/Position-Normally-Pneumatic-U-S-Solid/dp/B06WGRLX58/ref=sr_1_13?crid=5V29CNB41DD4&keywords=12v+solenoid+1%2F4+in&qid=1700523538&sprefix=12v+solenoid+1%2F4+in%2Caps%2C86&sr=8-13

 

[Zed Head]

6 hours ago, darom said:

3. The 'new' AAR is unpredictable. If I leave it alone, it will close (not completely) after 6 minutes. Two different days while testing - one day the idle is at 900-950 rpms, today it was at 800 rpms after warm-up. I feel the AAR shutter 'curtain' doesn't guarantee the same closure.

An AAR that works correctly is pretty satisfying.  It just works.  Your varying idle speed might be due to one of your other problems, not the AAR.  If you apply 12 volts to the AAR pins and it doesn't close completely, it's broke.