Decided to stop guessing and bought a colortune

[Healey Z]

I'm new to the whole multiple carbs thing.

I bought a uni-syn off of craigslist and was able to balance the flow of the SU carbs at idle and 2500 rpm.

I've watched the you tube and the Z Therapy videos on adjusting mixture and while I think I have it right, frankly I'm just not certain.

I broke down and ordered a colortune (Merry Christmas to me) where you can actually see the flame in the cylinder and know if you are running rich or lean. Below is the link and it has a video of it operating if you are interested. I've talked to a few people on the Healey Forum that bought it and all have thought it worked well. I will let you know as well once I receive it and give it a try on my carbed L28.

This is the best price anywhere; $50 delivered for a new one.

ebay link

[240260280z]

You will next buy an O2 unit ..... do not resist the force

[SteveJ]

Or get a CO analyzer. The advantages are not having to weld a bung to the exhaust, the ability to use it on more than one car, and the meter is integrated with the sensor. The advantage of the oxygen sensor is that you can easily get readings under load with datalogging tools, such as an oscilloscope.

[Zedyone_kenobi]

Any news on your results with a colortune?

[Ted.]

Thats actually a pretty nifty little tool. Would love to hear how it works out for yah

[motorman7]

I almost bought one. Mentioned it to the people at work and one of the guys had one. I borrowed it and (for me) it was pretty much next to useless. I could turn the dial at the base of the SU half a turn and not see much difference in color. Wasn't happy with that.

I stick with the two turn method, and then check the spark plug color after a couple hundred miles. That seems to work best for me.

[Healey Z]

I was going to wait until I had a full update, but here is what I did thus far. I put it on cylinder #2 and fired it up. It had an obvious yellow flame (rich). I adjusted the carb and then walked to the other side to see the color.....repeat that 10 times than called it quits.

I have to wait until I can get a buddy to watch the flame color while I adjust to see the point that it changes color. I am certainly much closer now than I was (3/4 turn rich or so), but I want to get it fine tuned. By the way, that would put me right about at 2 turns

I have a ton of work and family on the plate right now, but I will get some pics, or video posted when I get around to dialing it in.

[240260280z]

# of turns will vary with temperature.

Colour tune can not tell you what is happening under load. Setting jet depth to spec then reading plugs is most likely similar or better in results.

Measuring gases removes most guess work.

An interesting phenomena shown on the graph below is that HC's increase when pig rich and also when very lean.

Edited December 13, 2011 by Blue

[Zedyone_kenobi]

I would think this tool would be ideal. You have to set SU's fuel mixture at idle anyway, so it should get you pretty close.

I ordered a colortune this week. I am hoping that at night with the lights off, I will get a good color reading. I just want it a bit blue. I still think I am running rich as I am popping out of my exhaust anywhere above 4500 rpm.

That may be my needle though. I checked my records and I have SM needles in my rebuilt carbs. That may be too rich for a stock engine.

[LeonV]

# of turns will vary with temperature.

Colour tune can not tell you what is happening under load. Setting jet depth to spec then reading plugs is most likely similar or better in results.

Measuring gases removes most guess work.

An interesting phenomena shown on the graph below is that HC's increase when pig rich and also when very lean.

I'm with Blue, a WBO2 is a much more comprehensive tool for this purpose.

Concerning the HC phenomena, the reason behind that is at a certain point, a lean mixture will cause incomplete combustion (slow burn or misfire) which will release some unburned gasses into the exhaust. Thus, HC will increase.

The leanest an engine can be run without misfire depends on many factors, with the big ones being mixture homogeneity and combustion chamber design.

Anyone have a 5-gas analyzer laying around?

[doradox]

Also notice that the production of that evil greenhouse gas, CO2, is max at stioch. Every modern gas powered car has a device that maximizes CO2 production.

Steve

[Zedyone_kenobi]

Yeah, so cars are in essence, really good for trees.