What would that be for a jet-hot coated header?

Most of my headers are between 240 and 260 deg F.
I have 1 that is reading 214 deg. Is something not adjusted correctly?
What do header temps indicate?

 

If it's #2, I wouldn't worry about it. That pipe has an unobstructed path for the cooling air coming off of the radiator. This will tend to cool it at idle more than the rest.
When the engine starts to make power, it won't be any different than the rest.

 

Unobstructed? This is the 92 with all the mods in my sig. It seems strange to me that 1 header would be ~40d cooler than the rest. Are you sure there wouldn't possibly be a valve adjustment issue or igniton issue???
I'm not looking for a problem but I would like to fix any POSSIBLE issues.

 

You'd need to measure the exhaust gas temperature directly for a meaningful comparison.

 

I guess to clarify obstruction....it's 1 cylinder not cylinder 1.
Cylinder 4 is the cool one.
Short of drilling holes in my headers for EGT sensors, is there a different way of measuring my EGT's more precisely?
What is a low egt temp indicative of?

 

Low EGT usually indicates an incorrect mixture.

 

Is it consistently low? read it the next day, that hole is still low?
All those temps are very low. Is that a cold start? I would expect closer to 400*F just idling. Once you put a load on it it'll really warm up.
My IR gun doesn't read high enough to accurately tell me the temp on my headers...

jet-hot coated... are they too shiny to get an accurate reading perhaps? try using a sharpie or something to put a black mark on a few, you might not be getting a good angle on that header pipe?

 

Yes. Consistently low. Shiney jet-hot coat. Tried many different angles with the same reading. I'll try marking it with a sharpie if it doesn't burn off.

The car was idling for around 15 minutes when I took the reading.

 

you can hit it with a bit of black paint if you want. some acetone will scrub it off later...
that's really low for an idling car, IMHO. then again, maybe that's just the Jet hot working....

which car is this? could it be a semi-plugged injector?

 

It's the 92 GTA with the 383. All of 'em are low so i'm assuming that the jet-hot is working but the one is significantly lower than the rest.

I would hope it's not a plugged injector. They're Ford Bosch 3 36lbs with only 300 miles.

 

Shiny surfaces are very hard to get accurate IR readings of as they have low emission factors. Also, if you try to measure a glass pane or a polished metal surface you'll be measuring whatever is reflected off of it to a much higher degree than the object itself. Also I have the impression that ceramic coatings have insulating properties, thereby further lowering the measured temperature. A spot of matt-black paint is probably the best idea, apart from using a surface contact thermometer.

 

If you want to know for sure, move it to another hole.

 

I'm doing everything that I can in order to avoid doing that. Allen head bolts, AS&M runners, and the Bigmouth intake don't play well together.
Reading the plugs leads me to believe that it is firing. It's slightly darker in color than the plugs next to it.
I've also noticed that disconnecting any one of the injector connectors doesn't produce a noticeable difference in idle quality. Maybe it's the cam with it's choppy idle that's hiding idle misfires and issues.

 

Coated headers don't give an accurate reading. My primaries are coated. At an idle, they're around 200-250* using a laser heat gun. My EGT in the #1 pipe is around 500* at an idle. Although I went through an entire season without glancing at my EGT while crossing the finish line, I'm trying to get a fuel setting so that it's around 1200-1250* at the finish line. I really need a data logger with 8 EGT probes. My headers already have the ports.

Slightly cold can be any number of reasons. A huge reduction in temperature and I'd say the cylinder is dead. All at 250 and one at 70 and I'd say it's a dead hole. Only a small reduction and that cylinder is running slightly rich. More fuel means cooler temperature. Less fuel means lean and hotter temperature. It never hurts an engine to run a little rich but running lean burns up parts.

Since you normally can't change the fuel distribution to each cylinder, it has to be adjusted by other means.

A cylinder leakdown and compression test can give an indication why that cylinder may be burning more or less fuel.

You can try adjusting the plug gap for that cylinder to see if it changes how the fuel is burnt. You can also try a different plug heat range for that cylinder.

At an idle, the air/fuel going through the intake has too much time to move around and change. If you had EGT sensors in all 8 cylinders and there was a noticeable change in temperatures at WOT, I'd be more concerned about equalizing out the power to the cylinders.

On a typical dual plane intake, I wouldn't even bother worrying for such a slight difference in temperature especially at an idle. Worry if it's 100* or more at an idle.

 

Okay. I'll scratch it off of my "possible issues" list. I haven't done a leakdown since I pulled the engine as a 350.
I did do a compression test on my cold cylinder and a "normal" one right next to it and came up with 211psi and 216psi respectively.
Thanks for the info.