Decided to stop guessing and bought a colortune

[Healey Z]

That looks like a very narrow band. About how many turns of the knob would it take to pass from one end to the other of that band? 1/2 turn?

[Zedyone_kenobi]

That band is not color related Healy Z

the color of the flame is due to heat, leaner mixtures run hotter (whiter), while richer mixtures run cooler (more orange)

I do not think you will go orange/blue/orange.

I get my colortune tomorrow.. we can talk over the phone if you like and we can compare results and try out ideas.

remember you cannot tune one carb totally independent of the other. The balance tube dictates you will get some cross talk.

I have a testing arrangement in my head in mind, but I really look forward to playing with this toy. IN the end, I can easily see myself getting a portable O2 sensor, and getting fittings welded into my header. But this seems to be a great first shot.

I want to echo what Blue has said in countless posts... reading your plugs is an irreplaceable tool...to knowing what your engine is doing. It is the equivalent of drawing blood and running labs. Plugs do not lie. I just need a whole day to mess with this, and I am hoping to have a week off of work to play with my colortune.

Healy, PM me your phone number and we can chat if you like with our colortune experiences!

[mlc240z]

How about mounting a mirror on the plug side? Maybe just with a spring clamp that you could adjust for optimal viewing from the carb side.

[Healey Z]

Zed PM sent.

In the little playing I have done with the color tune, I can definitely change the color of from a yellow flame, to blue to one with white flashes, indicating from rich to lean. I would like to be watching the flame change as the carb wheel is being turned, so I can pick out the transition points and really fine tune the carb, thus the desire to have a buddy help me.

The unit actually comes with a tube and a mirror, but I didn't try it, because I didn't think it would be visible while I was adjusting the carb...but it may be.

Edited December 14, 2011 by Healey Z

[Gary in NJ]

Please don't take the conversation to PM. As a Colortune user myself I'm interested in seeing your results and discussing use techniques.

[240260280z]

Can you turn the lights off and just put some aluminum foil over the device or a diffuser to send the light in many directions?

http://www.youtube.com/watch?v=a9fpolCvM-8&feature=youtu.be

[LeonV]

That band is not color related Healy Z

the color of the flame is due to heat, leaner mixtures run hotter (whiter), while richer mixtures run cooler (more orange)

I do not think you will go orange/blue/orange.

Just FYI, this is not true. Flame temperature is a maximum with a slightly rich mixture (~13.5:1) and gets cooler as the engine is leaned or enriched from there. As far as color goes, I've done lab experiments with a glass engine (glass cylinder, you could see the piston move and combustion happening!) and from what I remember, orange was rich, bluish was probably slightly rich, and light-orange with flashes was lean.

Good luck. I'm thinking that installing a WBO2 while also using the colortune may yield some interesting results.

[Zedyone_kenobi]

OOOOh data with a reference measurement.. now we are talking!!! Add a few more sensors in there, and we will start getting in to NASA levels of measurement rigor. Ask me how I know!

[hogie]

The tube and mirror works fine for viewing the flame. You have to have the angle just right though. I haven't had much luck with my colortune. When it is set to the proper blue I lean pop. My rear cylinders I can't get quite right.

I have good drivability and good gas mileage, but my rear plugs get crappy pretty quick.

[Zedyone_kenobi]

do you pop from the exhaust or form the carbs?

[Zedyone_kenobi]

Hooked up my colortune in the number 1 position last night, dimmed the lights in the garage, and started her up. I had already warmed the car up by driving it for 15 minutes prior to this. When I walked around the car to see if I could see any flames, it was a beautiful light blue. When I revved the engine it turned very orange/yellow and bright!

So, initial diagnosis. My idle mixture is pretty darn close, and any throttle input is met with extremely rich conditions. I tried holding the throttle in a fixed location, and the flames never went back to blue, but stayed orangish. I will try using the screw to hold the idle dead steady and make a note what happens.

Well whatever I am I am not far off. So leaned it out a 1/4 turn and went for a drive. Car drives flawlessly up to 4000 rpm. Then as predictable as clockwork, it pops and stutters badly out of the exhaust.

I am starting to wonder if my oil level is wrong or maybe I need a different viscosity SU oil.

I checked my needles and they fall straight back into the jet smooth as butter. I know I have good fuel pressure, but I have not checked my float levels, but like Bruce says many times, They were set from Z therapy a year ago, and I see no reason why they would have changed.

So I am going to keep playing with this as best I can.

I will try to make a video of it working...if I can find my camcorder.

[240260280z]

Some quick carb theory:

There are two forces holding your SU's pistons down at any time:

1. Gravity (constant)

2. Spring pressure F~kx + delta x (where delta x is the excursion)

There is one force lifting your piston up:

1. Venturi Vacuum

The carb is supposed to be constant velocity air flow through the bridge/piston venturi from idle to WOT but I don't think it is (I plan to measure and model winter/spring time)

IF's

- if the piston is too heavy or the spring is too strong then the piston will rise less for each cfm flowing

- if the piston seal is poor then the vaccum lift will be weaker and the piston will rise less for each cfm flowing

- if the piston is lower than spec at a specific cfm then the venturi effect will be greater and pull more on the piston to self correct but it will always be lower than spec AND the greater venturi effect will also pull more fuel through the orifice.

So if you want to lean out at higher rpms, you have to alter the needle and at the same time balance how high the piston is at a particular rpm. The two parameters are intertwined.

I think the first step to understanding these beasties is to find at what rpm the piston maxes out and hits the roof. Should it be at max RPM or before? I hope to explore. If the piston maxes prior to max rpm then the venturi will draw more fuel between these points AND it is a restriction to airflow & power. If the piston maxes at max rpm then the venturi should be CV across the rpm range. Needles will have to be cut for each variation.

In your case, the richness above 4000 may be addressed by shooting an in-engine compartment video of your piston height vs rpm (use a remote USB camera).Check to see where the piston height is.