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Colortune usefulness?

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J

Jim Lee

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Hi all,
I have a very rich running TR3A where the plugs are getting blanketed by dry black carbon soot pretty much immediately after I put them in. I think it is bad enough that it is at least contributing to a real lag under load. For example if I am in 2nd or 3rd gear and I step on the accelerator too quickly there can be a very distinct and irritating hesitation before the power kicks in. I am going to first try changing the oil in my carb dampers from Marvel Mystery oil to something thicker but it seems pretty clear that I am running very rich. The plugs have a little bit of gloss on the threads but the working area is black dry soot like a coal color. There are flecks of what I can only describe as silver, matches almost exactly the color of the anit-seize I use but is not anti-seize, here and there. All comes off very easily with a wire brush on removal but I am getting tired of removing.

A local store carries the colortune kit where you substitute their colored plug for a plug and are able to determine the correct fuel/air mixture based on the color. That sounds like a much more efficient way of adjusting my needle than turning flats and removing plugs and wondering if I idled too long etc. The main question I have is if the idle mixture, which is what I assume you would be looking at with a colortune, is going to be helpful in trying to get rid of the hesitation that I am experiencing which is decidedly not happening at idle.
The engine idles very well.

Also, I should know, or look this up but standing above the carbs do you turn the adjusting nut clockwise to lean out the mixture?

Thanks very much,
Jim Lee
 
Jim, Never tried the colortune but will be interested in the response.
Counter clockwise to lean as it's raising (righty tighty) the jet body. Try a flat at a time.
I always remove the dashpots/jet assembly first and use a vernier gauge to make sure both jet bodies are at the same position. Measured from the bridge .050 is a good starting place. Also check that your pistons are free and not hanging up as this can lead to a very rich/choppy idle.
 
Hi Jim,

I used a Colortune kit when I rebuilt my TR250 ZS carbs five years ago. My car has run strong ever since, without any other fiddling with or correction to the carbs. I did NOT replace my throttle shafts, and as a consequence my idle is a little lumpy--I think I have the carbs set slightly richer than they should be, to compensate for the extra air that's leaking past the worn shafts and new seals. Next time I pull the carbs you can bet I will replace the shafts!

Anyway, a big Yes from me on the Colortune. It's very cool to see what's going on in there.

Regards,
 
I have a ColorTune but have never felt it worked well on dual carbs. I've loaned it to people setting up single SUs and they have been pleased.

As a minor point, don't wire brush plugs. Wire brushes can leave a thin metallic film on the ceramic which can cause plugs to misbehave and/or misfire. There are a number of different ways to clean plugs. If you don't already have a sandblaster you may want to consider buying one of two items from a place like Northern Tool (www.northerntool.com). The first is the useful but messy "blast out of a bucket" sandblaster for about $20 (Item# 155560 ). If that's too big for your available space, consider the micro-sandblaster that's like an air brush for about $33 ( Item# 522603 ) .
 
I love my colourtune. What I did was buy two of them. I use one in number 1 cylinder and the other in number 4 cylinder. That way I can tune both carbs at once and see what they behave like as I open and close the throttle. Given how little they cost I feel I got a huge bang for my buck out of them.
 
Adrio,

If one is good, two is better, right?

I did my front carb first, and then moved the Colortune to one of the rear cylinders to adjust my rear carb. Actually, I was having so much fun I eventually put the Colortune in each and every cylinder. How sad.

I like your idea of using two at the same time. Seems like it would get the car closer to optimum, faster.

Thanks and regards,
 
I would certainly try a thicker oil in the dashpots before doing other stuff.

Sooty plugs may still occur to some degree even with the mixture correct dur to both the tendency for them to soot up at idle and possibly modern gas formulation.

Easy way to recall which was to turn the mixture nut (when 'viewed' from above) is Left=Lean... Right=Rich.
 
I've used my Colortune to mixed results. We worked on a friends Healey 100 and they seemed to work well.
With my old TR6 and my TR3 I could never get a consistant color. They would go from good to rich and back. I ended up doing the finishing touches by checking the plug colors.
 
I've had two for years and think they're a great tool for adjusting the low-end mix. Try putting whatever oil you use in the crankcase for the dashpots... MM oil is a bit light for 'em, especially considering the age/wear factor. P'raps even consider new "barrels" for the rods. Heavier viscosity for the dashpots should help tho.
 
I have never been impressed with Colortune plugs. Just me.

Or course, it's a little tricky with trips.



Bill
 
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