Carb Tuning with IR thermometer?

[Stanley]

Anyone successfully use one of these for tuning the carbs? Bought a gen-tech IR on sale at Harbor Freight, tried it out a couple times.

I'm running SU's on a 240 with stock exhaust manifold. I can see it would work better with headers. You can get a good shot at the first and last exhaust runners about 2 inches from the head, the 2 middle ones are obstructed by the intake so you can only take it's temp very close to the head. Noticed the front is about 100 F lower than the rear one so maybe the rear carb is lean? I know the manifold is open inside so I guess it wouldn't help to check the down pipes.

How close to the manifold should I be holding the gun? Noticed it needs to cool down a couple minutes after being close (about 5 inches) from the manifold until it gives an approximately correct reading of say the car body.

Would it be better to check the temps somewhere else, maybe by the spark plugs?

Looks like it might be helpful but I'm getting the "don't know what I'm doing" feeling.

Edited March 1, 2013 by Stanley
incorrect word

[240260280z]

Measure the temp front to back on the spark plug side to see if there is a gradient.

You can measure this along the head and along the block.

Measuring spark plugs is nice data too.

[Zed Head]

The closer you get the IR gun the tighter the spot measured will be. Many have a diagram of the beam spread in the instructions or on the tool itself. If you're too far away you'll get an average of the hot exhaust and cool intake and other parts.

[Captain Obvious]

Getting an accurate reading with those IR guns can be difficult. Not only the distance from the target, but the accuracy also depends a whole lot on the emissivity of the material being scanned. Shiny stuff like intake manifolds, aluminum head, or stainless headers can be trouble.

You can read a bunch here about how to take more accurate measurements:

Noncontact Infrared Temperature Measurement | Emissivity Measurement ? Raytek.com

Emissivity of Materials | Thermal Emissivity*? Raytek.com

[Wade Nelson]

You can't tune a car sitting in a garage. It's how much fuel that's getting delivered under LOAD that matters. Drive, adjust, repeat.

[Stanley]

Well, was just checking temps at the plugs as mentioned above when Cen-Tech just bit the dust. Guess three 10 minute sessions were too much for it. Can anybody recommend a reliable IR? "Drive , adjust, repeat" sounds right though.

[John Coffey]

You can't tune a car sitting in a garage. It's how much fuel that's getting delivered under LOAD that matters. Drive, adjust, repeat.

Exactly! Plus the engine fan will cool the front of the exhaust manifold more then the back. I've very skeptical that an engine can be tuned with an IR gun.

[Lazeum]

can't it be done for idle only though?

I've been thinking about it somehow to finely tune my DCOE. My spark plugs look identical, carbs are well balanced but it would be cool & intereting to know, wouldn't it?

Issue such as fan cooling header #1 has to be overcome as Jonh says

[John Coffey]

My spark plugs look identical, carbs are well balanced

Sounds like things are already well tuned.

[Zedyone_kenobi]

You are at the point where you need EGT on each cylinder. But the output may not be that useful. We can only tune so many screws. The older Z's have no feedback, so you will have to pick where you want to run. Also, are you tuning for power, or efficiency. While I think that installing EGT's would be cool, I am not sure how much more beneficial it will prove over just a standard Wide band. Now if you could datalog real time and use redlines to shut down the engine incase soemthing bad was happening to one cylinder or another, it would be very useful. I can imagine many situations where it COULD be useful, but the trouble of installing them and monitoring them may prove more work than worth.

[Lazeum]

Sounds like things are already well tuned.

Dad is always asking me: "why do you touch your car? it's running well"

I'm not the only one here who can't stop improving & learning stuffs. I'm just (too) curious - like many others in this board & on hbz.

For information, I've tuned mine with a wide band (Innovate LM2) & a synchrometer.

Edited March 4, 2013 by Lazeum

[Zedyone_kenobi]

LOLLOLLOL