Return of the Z - Bleach's 280Z turbo build (1978)

[datsunfreak]

On 6/25/2023 at 3:54 AM, Bleach said:

I also figured out during all of this that the distributor vacuum line is not supposed to go to the intake manifold but it is intended to connect to the bottom of the throttle body. By connecting it there, the timing will be more correct at idle.

 

Yes, the intake draws too much vacuum at idle for the plate to work correctly (and for the timing to be smooth), and on boost it could cut off all your vacuum advance. 👍

[datzenmike]

It SHOULD cut all vacuum advance. You don't want any advance other than initial and mechanical if the throttle is full open and if anything some retard under boost if preferable.

[Bleach]

I don't have to worry about boost yet with this engine. Although the thread does say it is a turbo build, the L28 turbo engine is still on a stand.

 

The factory L28 turbo distributor will come later and that does not even use a vacuum advance. I think it is all electronic settings based on the crank angle sensor... if I remember correctly.

[Bleach]

The OEM throttle body is on and the high idle solenoid is off.

 

[]2eDeYe]

Progress B)

[Bleach]

The intake boot is on, throttle position sensor, and some old throttle return spring that was elsewhere on this car when I bought it. I picked up some generic springs from the auto parts store to see if I can find a better fit.

 

 

After connecting the valve cover breather to the intake, I did more research knowing that this was going to have high vacuum at idle. This is not a good way to connect it. The valve cover should still go to low vacuum in front of the throttle plate. I'll get that fixed.

 

[Bleach]

New hose ran to the proper port on the intake.

Block-off plate made and installed on the top of the throttle body.

 

I'm going to now replace a couple rubber fuel lines near the tank and fuel pump. That will complete the replacement of all rubber fuel hoses on the car.

[Bleach]

I replaced the fuel hoses around the pump.

I found that a hose I replaced just five years ago was cracked and leaking right at the clamp. I have only put on a few hundred miles in the last five years so this was surprising.

 

After all of them were replaced and new fuel injection hose clamps installed, the car started. Fuel leaks all over. 😞

I'm Doomed

 

I really wanted to test drive today and not be set back with fuel leaks.

[Bleach]

I figured out my error. I was using 3/8 inch fuel hose. While that fits and feels correct on the metal tubes, it takes a lot of clamping force to keep it sealed.

 

This Datsun Z should be using line that is 1/16 smaller. 5/16 hose installed and sealed without an issue.

 

I also looked up where the vent and feed/return lines are. Someone had incorrectly hooked up the fuel return to one of the vent hoses at the top of the tank. This probably doesn't hurt anything but I connected it to the correct return near the bottom of the tank.

 

Also, lifting one side of the car does work well to move all the fuel to the other side of the tank so you have minimal spills. 😄

 

[Bleach]

- Fuel lines replaced and all sealing well

- Distributor replaced and vacuum advance working

- 280ZX OEM throttle body and intake boot installed

 

During test drives, the car would still hesitate and pop a little under partial throttle acceleration. This ended up being caused by the throttle position sensor.

I have several TPS so I swapped one of the others which may be from a 280ZX. (matching the throttle body that it is now installed on)

I pulled off the black plastic cover so I could see the contacts and align it to correctly contact the idle switch when the throttle plate is closed. Just into the throttle opening (10% open?) the switch connection should be "off" which gives more fuel. The last part is not adjustable but the wide open throttle position looks to contact at about 60% throttle opening.

That solved the issue with the throttle hesitation while driving. Now the car is doing well. I did not get this fixed and tested in time for Powerland.

 

I also set the idle speed at this point. Once warmed up, idle is set to 900 rpm. That might be a little high but I don't have a cold start idle valve. When the engine is cold, it does idle on its own at about 500 rpm and then slowly climbs as the engine gets warm. This works for me.

 

I did take the 280Z to a small Z club meeting in Tacoma and I drove the car around that day. I got about 3 hours total time driving. It drives well and starts up every time.

The radiator leak looks to have fixed itself as I no longer have to fill the radiator. I did buy a new radiator anyway. That arrived just yesterday.

[demo243]

Car is looking good!

[Bleach]

I purchased one of those inexpensive aluminum radiators made for the 240Z/280Z. That installed fairly easy and all four mounting bolts lined up.

While I was in there, I removed the AC system from the entire engine compartment.

I also removed the factory fan and tested the car. It was able to hold proper temp while standing still with no fan or wind going through the radiator.

New aftermarket throttle return spring cut to custom length and installed.

I cleaned the K&N air filter and bent it back into shape.

 

 

[]2eDeYe]

Nice work, looks great. 

[Bleach]

With no fan installed, I drove to a Z-Car Show in Tacoma.

I did get an award for favorite "Work in Progress" z car

 

My car is at 24:43 in this video