5 minutes ago, 240260280 said:

Note: There is a need to have fuel pressure on the valve for accuracy.  Column of water or fuel in a vertical hose can do this w/o needing a pump.

 

You can also idle the car then shut it off and measure fuel bowl level.

Sorry, not sure I follow. I've been using Randalla's Float Sync's during all of my tuning, which were really helpful in immediately diagnosing that my float bowls were drying out.

Measuring the fuel level in a small jar by pouring in the top is brilliant an is  great for ensuring both fuel levels are exactly the same but this is basically for 0psi fuel pressure.

If you apply 3.5 to 4psi, you will find the valve opens and the fuel level goes up higher.  Measuring on a running car or with a head of fuel does not have this issue.

Edited November 23, 20204 yr by 240260280

25 minutes ago, 240260280 said:

Measuring the fuel level in a small jar by pouring in the top is brilliant an is  great for ensuring both fuel levels are exactly the same but this is basically for 0psi fuel pressure.

If you apply 3.5 to 4psi, you will find the valve opens and the fuel level goes up higher.  Measuring on a running car or with a head of fuel does not have this issue.

Ah yeah you're totally right, I was just setting the fuel levels with my funnel while my gas tank was in the shop.  I re-adjusted yesterday during the brief period that my fuel pump actually worked, and and had to make minor adjustments as you'd expect.

 

4 hours ago, 240260280 said:

Column of water or fuel in a vertical hose can do this w/o needing a pump.

Just out of curiosity I calculated how high that vertical hose would be to get to 4psi:

p = ρ g h

• p = pressure in liquid (N/m²)
• ρ = density of liquid (kg/m³)
• g = acceleration of gravity (9.81 m/s²)
• h = height of fluid column - or depth in the fluid where pressure is measured (m, ft)

Using ρ=750 kg/m³ for the density of gasoline and 4psi = 27579.04N/m² for our pressure we get a column height of ~3.75m = 12.3'. That's a lot of hose!

As always, I've got some good news and some bad news.  The good news is that I installed a new K&N fuel pump, and the process couldn't have gone better. The float syncs are now showing near perfect fuel levels in the bowls, with the bonus feature of being able to tune the levels without Hoover's ladder.

The bad news is that something is still very off with the mixture.  Using the standard 2 1/2 turns down on the mixture knobs the car will barely start, runs very rough, and pours enough dark smoke out of the tailpipe that people on their afternoon strolls cross to the other side of the street. Good thing they're already wearing masks.  

As I turn the mixture knobs leaner and leaner, the car runs better and better.  I bought myself a Gunson Colortune, and verified that even with the mixture knobs cranked all the way up I'm still running rich (see video below). I made sure that the chokes are pushed all the way up, so I don't think that's the problem.  I suppose the next thing to check is that the needles are seated properly in the carb piston, or possibly the needles are just totally wrong themselves.  Anyone have any other debugging advice I could try?  Is it possible that my timing has something to do with this?  I'm pretty sure I'm somewhere between 15-20deg advanced, but this is honestly my first experience with a timing gun so it's possible I'm screwing that up. I tried shifting the timing around a 5deg each way and didn't see an appreciable change in the spark color.

EDIT: I just had another thought.  I have no idea what the story is with the coil on this car, but it looks like it's the factory original one. Is it possible that my mixture isn't actually rich, but I'm just not fully combusting because of a weak spark from an aging coil?

 

 

Edited December 12, 20204 yr by rcv

You say the float level is spot on, what are they set to?

Edited December 13, 20204 yr by heyitsrama

56 minutes ago, heyitsrama said:

You say the float level is spot on, what are they set to?

My set point is 23mm down from the roof of the lid, which comes out to 14mm up from the base of my Float Syncs. I'm actually maybe 1mm off from that, but if anything I'm a little low so I can't imagine that's my problem.

 

Edited December 13, 20204 yr by rcv

Ok, so I replaced my OEM ignition coil / ballast resistor today with a Pertronix Flamethrower coil and new resistor.  The car seems to run a bit stronger, but the mixture is still way too rich.  My colortune is showing bright orange even with the mixture screws all the way in.  Backing them off at all just causes the motor to bog down and run like junk. 

I also tried re-seating the needles according to the Z-Therapy DVD instructions, but that made no difference.  I'm not really sure where to go from here.

Edited December 20, 20204 yr by rcv

Have you verified which needles you have and that they are in good condition?

The needles looked ok to me when I pulled them out today. No pitting or scratches as far as I could tell. I didn’t see any markings on them to indicate what kind of needles they were though. It was getting dark though, so I could check again in the morning. Should they be marked on the shoulder?

I believe SM's are the standard needle. I don't know if they are all stamped. If the float level is right and holding then needles would be my first suspect

The factory standard needles are N-27, but a lot of people install SM's instead. That decision works out well for some people and some others report running rich.

The number is either stamped or inked onto the hilt and is only able to be seen with the needle removed from the suction piston. However, if they are inked (and not stamped), the ink printing is pretty fragile and is often destroyed with handling or chemicals. In other words... It would not be unusual for you to pull the needles and find only remnants of the number stamp and not be able to tell what they are from the ink printed mark.

It's easy to make the carbs run lean, but it's usually a little more difficult to make them run rich*. To run rich, it takes deformation of a needle or a nozzle, or the installation of incompatible parts.

Did you ever get in touch with Paltech and ask what needles he used?

 

* Assuming, of course that the float levels are OK and the nozzles are not sticking down with the choke.

Edited December 20, 20204 yr by Captain Obvious