Lean cylinder, high EGT, beautiful pics!

Engine troubles? Try here.
Post Reply
boeing7873
Argentina
Posts: 151
Joined: Sun Dec 21, 2008 10:50 am
Location: Atlanta
Contact:

Lean cylinder, high EGT, beautiful pics!

Post by boeing7873 » Mon Apr 16, 2018 10:25 pm

I bought a thermal camera and started playing with it to find the culprit to some stumbling on low RPM acceleration. Check these pics out!
Jerome
CRJ Driver

boeing7873
Argentina
Posts: 151
Joined: Sun Dec 21, 2008 10:50 am
Location: Atlanta
Contact:

Re: Lean cylinder, high EGT, beautiful pics!

Post by boeing7873 » Mon Apr 16, 2018 11:06 pm

Another try at posting pics....
Attachments
rsz_flir_20180416t203043.jpg
rsz_flir_20180416t203043.jpg (48.24 KiB) Viewed 654 times
rsz_flir_20180416t202515.jpg
rsz_flir_20180416t202515.jpg (39.11 KiB) Viewed 654 times
Jerome
CRJ Driver

boeing7873
Argentina
Posts: 151
Joined: Sun Dec 21, 2008 10:50 am
Location: Atlanta
Contact:

Re: Lean cylinder, high EGT, beautiful pics!

Post by boeing7873 » Mon Apr 16, 2018 11:08 pm

A few more... Obviously something is wrong with my last cylinder...
Attachments
flir_20180416T202437.jpg
flir_20180416T202437.jpg (156.69 KiB) Viewed 654 times
flir_20180416T184545.jpg
flir_20180416T184545.jpg (255.2 KiB) Viewed 654 times
flir_20180416T184442.jpg
flir_20180416T184442.jpg (265.99 KiB) Viewed 654 times
Jerome
CRJ Driver

pinzinator
Posts: 795
Joined: Thu Jul 29, 2004 3:12 pm
Location: Indio, California

Re: Lean cylinder, high EGT, beautiful pics!

Post by pinzinator » Tue Apr 17, 2018 10:02 am

Are the valves set correctly on cylinders 1 and 2? Is the front carb jetted the same as the rear?

User avatar
rmel
United States of America
Posts: 949
Joined: Sun Sep 25, 2011 12:19 pm
Location: Woodside, CA
Contact:

Re: Lean cylinder, high EGT, beautiful pics!

Post by rmel » Tue Apr 17, 2018 10:17 pm

It will be hard to draw a conclusion from a Thermal imaging camera -- there's a fair amount
of error you can have versus the actual gas temperatures in the pipe. The only foolproof
measurement is with Pyrometers in the pipe and each at exact locations on the exhaust ports.

For accuracy measuring externally, your better off with a narrow beam IR gun with a Laser
spot -- and you want to get that spot exactly at the same place on each exhaust port. Your
imaging camera looks like it may support a spot beam? At that there's a number of things that
can throw the measurement off. The surface roughness of the metal, and if your headers are
treated with ceramic coating it's going to read very low and with variance -- I'm guessing that
is not your case though.

Even with Pyrometers in place, Temperatures at idle can show a significant variation from port to
port due to low flow rates, air mix and advance at idle. Try measuring the temperatures above idle,
at least up 2,000 to 2,500 RPM.

From my experience, idle temps are over 350C -- as measured in the tube. At load, chugging up a
steep grade for a period of time your going to be running about 650C on the coolest typically #1
and up to 800 on the hottest typically #3.

So you may or may not really have a problem here, but try higher RPM and see if things flatten
out a bit more -- and you should expect some variation between each port, up to 20% or so. Three's
air flow difference between these cylinders, also #2 and #3 have hot cylinders on both sides, then
there's the fuel flow differences etc etc.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

boeing7873
Argentina
Posts: 151
Joined: Sun Dec 21, 2008 10:50 am
Location: Atlanta
Contact:

Re: Lean cylinder, high EGT, beautiful pics!

Post by boeing7873 » Mon Apr 23, 2018 1:48 pm

Excellent advice, will shoot the temps at 2000 RPM or more. Also, I took some new measurements with the camera and noticed the temperature readings vary with the angle from which they are shot. Getting closer to the pipes reduced the temp difference.
JC
Jerome
CRJ Driver

Post Reply