Carburetor Conundrum (260Z)

[w3wilkes]

Looking further at your pics the jury rigged throttle return spring looks weak. Those carbs should have a spring on each carb going down to the heat shield between the intake and exhaust manifold.

[w3wilkes]

8 minutes ago, SteveJ said:

That's a good observation, @w3wilkes. @DadAndLadZ, you should probably check your fuel pressure. With not having the stock fuel rail, you lack the fuel pressure regulation afforded by the orifice in the return line. 

I would guess fuel pressure should be okay. If I'm right this is dead headed. We'll know better with a pic of the passenger side where the fuel supply and return fuel lines are. If it's dead headed the return line should be capped

[DadAndLadZ]

42 minutes ago, w3wilkes said:

Curious how the fuel lines go to a "T" and then over the top of the valve cover to... what? How about a pic of the other end of the single fuel line that goes over the top of the valve cover. I'm guessing it just goes to the hard line on the right inner fender? I'm also guessing you have an electric fuel pump at the tank? Or is there a mechanical pump on the passenger side of the engine?

The single fuel line goes over the valve cover to a fuel filter, which is connected to the hard line from the electric fuel pump mounted near the gas tank. It pumps pretty good but I have not actually checked the fuel pressure and not sure how to do that?

I can tell there is a bunch of stuff missing and/or Frankensteined here but being unfamiliar with these cars in the past, it's hard for me to get my head around what I'm looking at. I really appreciate the insight from you folks... I tried another Z Car forum first and it's like crickets over there! Will probably be the weekend before I can get back out in the garage and fiddle around with it some more, but will def keep this thread going as I move forward. THANKS most sincerely for all the input.

[w3wilkes]

Here's how the throttle return springs should be hooked up. There's one on each carb.

[DadAndLadZ]

9 minutes ago, w3wilkes said:

Here's how the throttle return springs should be hooked up. There's one on each carb.

 

Interesting, thank you!

[Captain Obvious]

Seeing your pics, you do have the return springs on the carbs (hooked down onto the heat shield), so that's not it.

With a quick look, I do see some stuff that isn't right though...

The long hex nuts that go onto the throttle butterfly shafts are loose on both ends. The front carb is loose, and the rear carb is missing a lock washer and is loose.

The top front return spring kludge appears to be pulling the center linkage in the direction that would increase throttle position. If it's fighting against the front carb return spring (and winning), that will open the front carb and raise the RPM. You shouldn't need that spring at all.

I'm not currently in position to annotate pics, but I'll do that later tonight unless someone beats me to it.

And also... Yes, the cables are choke cables. When pulled, they also open the butterflies some to raise the idle speed. So it would be important to make sure the cables aren't pulling the carbs open.

[DadAndLadZ]

4 minutes ago, Captain Obvious said:

Seeing your pics, you do have the return springs on the carbs (hooked down onto the heat shield), so that's not it ...

Oh man, I will check out everything you said. I would be very grateful for you to annotate. Here are some pics of the supply side, as requested above, too.

[DadAndLadZ]

Here is a short video showing the fuel lines: 

 

[w3wilkes]

One thing I notice is this spring I've circled in red. Remove it and just let that lever thing it's attached to flop around. That lever thing is for a partial throttle opener on deceleration but the emissions part that connects to that lever has been deleted. As it is the spring would be fighting the throttle close springs on each carb.

[Captain Obvious]

9 minutes ago, w3wilkes said:

One thing I notice is this spring I've circled in red. Remove it and just let that lever thing it's attached to flop around. 

Yup. That's the one I referred to as "the top front return spring kludge".      Much easier to identify with your annotation on the pic.

The way is right now, it's pulling the throttle ON instead of pulling the linkage off.

[w3wilkes]

Still looking at your pics and want to verify that you have throttle return springs attached to the 2 circled levers and go down and attach to the heat shield between the intake and exhaust manifolds.

[DadAndLadZ]

2 minutes ago, w3wilkes said:

Still looking at your pics and want to verify that you have throttle return springs attached to the 2 circled levers and go down and attach to the heat shield between the intake and exhaust manifolds.

 

There are.