Where is the best place to mount a EGT probe on 4-1 headers? I have triad headers with a triad muffler.

Somewhere after the 4-1 collector, following the instruction for placement that came with your probe (usually somewhere between 1 and 3 o-clock on the pipe).

Zach

That would be correct for an O2 sensor.

Best place for EGT is about 4-6" past the valve head but any place before the first bend on a T4 exhaust will work just fine.
Some people go to the trouble of mounting them in the stub pipes.

I put them here on some dansk bus heat exchangers. Someone was saying that the position around the curve, like if they are on the inside vs the outside radius would affect them. I haven't seen anything to back that up, and it's hard to tell, since I have 4 barrel carbs. Supposed to be closer than 2inches to the port will shorten probe life I read.

I plan in only installing one egt probe. My car is mainly used for street driving and rare auto x. I am installing the egt just as an extra monitoring tool for tuning and such.

-is it ok to only install a probe in one header, for my purposes? I realize in high end race cars that you would want a probe in all cylinders however that is not me.
-if ok, then does it matter which cylinder I choose?

not sure what value a single EGT probe would have.

The reason to put them on each pipe is so you can ensure your carbs are setup properly and a balanced mixture/burn is happening.

One probe at a collector location will just tell you the exhaust is hot.
It wont tell you anything more.

One O2 sensor at a collector location may provide some tuning information, but one EGT probe is (in my opinion) a waste of time and money.

rich

I was planning on installing a probe right after the stub pipe on my headers on cyl 2. I was hoping to use the info to help me tune my carbs. I was hoping that the one prove would give me enough info to get me close to properly tuned the base my other cylinder adjustments off cyl 2. Would this be reasonable or am I just dreaming.

I don't mind buying 4 probes but I didn't really want to fork out the money for a 4 channel gauge. Is it ok if I install a probe in each header and only have a single channel gauge? I could tune one cylinder, the hook up the next probe and then tune the next cylinder. Would this work? Would this be better than a single channel?

If its a street car, forget about EGT.
You need at least one CHT probe mounted under a spark plug, and an air/fuel meter with the probe located right after the collector.

If you are talking about tuning 4 barrel carbs, It is super finicky as the mixture affects the idle, balance everything interties. You need both carbs working as hard as each other. There are multiple factors that will cause any cylinder to be hot or cold.

Despite the probe install etc, I have only got it to work like once. I was using an Innovate tc-4 4 channel thermocoupler amlifier through an lm-2 into a laptop. Innovate is crap. Problems getting the lm-2 to sync with windows, bluescreens, hours and hours messing with it and managed to break the ac input plug to the lm2. As a last ditch effort, I am going to get the cord to go directly from the tc-4 to the laptop. For those few minutes that it worked, it really was magical.

Ok, maybe I should change the focus of my original post. I have dual weber 44 idf's on my 2256. I have an innovate lc1 with gauge. I also have cht senders on cyl 1,3 spark plugs. My big problem is that I am paranoid that although my overall air fuel mixture is ok, engine is running okI may still have some sort of a air fuel problem. For example lets say cyl 1,2 had mixture of 11 and 3,4 had 16. That would give me numbers around 13-14.

My cht numbers are 300 on cyl3,4 and 290 on 1,2. My oil temps are generally good however they can get very high after driving heavily for awhile. I do have an external cooler. My spark plugs on cyl 1,2 are white and on cyl 3,4 they are black deep in on the porcelain however white near the electrode.

I think there are too many factors that are off and I am getting confused. I was hoping the egt may help me get things situated however that doesn't appear to be the case.

Any thoughts? (Other than take it to a reputable mechanic- that's no fun)

After all that messing around with egt probes, I busted out a cheap infrared thermometer gun thing.

The bungs were a good target but if you can point it somewhere remotely consistent on all 4, somewhere near the stubs, you may find it enlightening.

It's tricky because with the probes, the response is instantaneous, but with the infrared gun you need to rev it a bit once you make an adjustment for the change to show up. You would be looking for them to all be about the same, to make sure they are on the same side of the stoichiometric curve. It will tell you if they're balanced, too. Either side working harder will be hotter. It seems to work well to set the air correction screws, too, since mixture can compensate to even them out, but might make 1 leaner.

I used to use a Gunsen Color Tune, but I think the infrared thermometer works better (and no chance of stripping out the threads in the head). Not as good as probes or even class K thermocoupler ring terminals on the bolts, but way better than just a snail.

If you want to install only one sensor install it a the hottest one. e.g. #3

CHT is going to vary because the cooling fan setup works the worst for cylinder #3
That is why people watch that cylinder temp...

If you are worried about the variation that can occur for each cylinder, 4 EGT probes are the solution.

Can you use one probe and keep moving it...sure thing.

I tune a car and then its done.
So, unless you change elevations on a regular basis...once the carbs are tuned, you are all done.

rich

It doesn't work that way. EGT is too finicky. You'd be starting and stopping the motor like 100x before you were done.

What I was getting at was leaving it in until I am done tuning that one cylinder then moving to the next cylinder. Sounds like a pain though.

problem is that you would need to move it back to the 1st cylinder to find the 2nd cylinder has changed everything on it.

Like, you might find cylinder 1 is cold, you try leaning it and it gets hotter, but now balance is off with the 3/4 side, plus 2 on that side is now off, as well. Switch the probe to 2 and adjust that and then back to 1... Nevermind 3 or 4 even.... It's all about 'going around' when it comes to tuning dual carbs. there is no 'set one cylinder and then the next' - they are all connected.

If its carbs, you don't have the fine tuning available that you get with efi...so it may require having 4 probes for efi....

Probes are cheap and the gauge is just reading voltage, so a few Walmart volt meters would also work for tuning.

Again, once you find the setup that is perfect for your carbs, on your motor, you are done.

It may be way more information than you need for carbs but go for it.

Rich

Or...
Four probes
One gauge
A 4 channel switch from RadioShack

Ten you can switch the gauge to different probes

The probes are actually pretty spendy. They list for about $90 a piece, the innovate (cheap) ones - I found them cheaper on ebay. You need a 4 channel thermocoupler amplifier also, like Innovate's tc-4 which is like $100-$150 depending where you get it. You can use the tc-4 without the probes, just k thermocouplers to save money. I can see using 1 channel on efi because there is no per-cylinder adjustment, but carbs have ay more adjustment.

Not sure what generation you are, but I have tuned carbs for years by reading plugs.

So, one sensor and gauge is a whole lot more than I ever had...and one does work.

Not everyone can afford everything and the OP is looking for a cheap solution.

One sensor will work if that is what he can afford...
A single sensor and a single gauge.
Oh, btw...I do know how they work.

Carbs a far easier to tune than EFI' so don't over think it.

Based upon your elevation, your camshaft, and your head combo, I know at least five people that can give you a very decent base setup for carbs that will be damn close to right on the money.

You may be over thinking this and you might want to spend your small budget on other more important things than a gauge you may never really need.

Rich

Reading plugs isn't what it used to be with today's fuels. Also, a big factor for me in moving from the relatively inaccurate Colortune to egt probes was stripping out a spark plug thread. -I cringe to hear people taking out plugs hot, which is the only accurate way to read plugs.


It all depends on how well you want it to run We've talked about several options and price points here from an infrared gun to thermocouplers to probes.


Again, best save your money on that.


I don't really, but the tc amplifier is like a preamp in an audio system it would seem.


Again, it all depends on how well you want it to run. It's easy, sort of, to make it run, but to make it run well... I don't see that much. Most people's carbs run like pigs. Richness hurts performance. Carbs are forgiving, one should say, not easy. There is a lot of performance and drivability to be had just through tuning.


The issue isn't jetting here, it's setting up the mixture, air correction, and the linkage. There are plenty of variables to be considered.


Agreed... about the budget. The innovate option is crap and the next level up is fairly ridiculous in price. I do recommend, if you have carbs, get an infrared gun and aim it at your exhaust stubs.

I should point out that I don't mind spending the money for a 4 prove setup if it is going to be valuable for me. Considering that I generally don't race my car, $500 +\- seems a bit too much to spend on that. I already have a single probe setup, it's just not installed. I think I'm gonna just use an ir thermometer on the stub pipes.