M20G hot temps

[IgorD]

Hello,

 

Looking for some help as I am having issues with hot temps in level flight. My back two cylinders are hovering north of 400 in level flight.  Doghouse baffling is sealed tight, timing is set as I got two new mags installed, cowl flaps are fixed and are open as much as they can be, spark plugs are new champion urem38.  My mechanic said just run it and watch for temps on the climb out. Weird thing about my number one cylinder is running bellow 300 and my number four is at 405 in level flight.  Oil temp is at 205-210 as well.  Any ideas are greatly appreciated. 

[carusoam]

Igor,

Got any JPI data to share?

CHTs are a two part equation… cooling and heat generation…

Sounds like you have the cooling issues really well looked into…

EGTs can give some insight into how well your fuel is being distributed amongst the four cylinders….  See if everything is even there or if some simple technique can improve that too…

 

Having FF data to go with that can also be helpful…  Some carburetors can benefit by having the right fuel nozzles installed…. Some carbs have had the wrong nozzles from decades ago…

PP thoughts only, stuff I have read around here…

Best regards,

-a- 

[IgorD]

3 hours ago, carusoam said:

Igor,

Got any JPI data to share?

CHTs are a two part equation… cooling and heat generation…

Sounds like you have the cooling issues really well looked into…

EGTs can give some insight into how well your fuel is being distributed amongst the four cylinders….  See if everything is even there or if some simple technique can improve that too…

 

Having FF data to go with that can also be helpful…  Some carburetors can benefit by having the right fuel nozzles installed…. Some carbs have had the wrong nozzles from decades ago…

PP thoughts only, stuff I have read around here…

Best regards,

-a- 

My JPI shows 14 to 15 GPH on the climb out 25/25.  EGT's are in the 1250's.  One odd thing that occurred coldest cylinder peaks first when I use lean assist feature on EDM700.  Has anyone re-directed airflow somehow from cylinder number one?  

[Hank]

Why climb out at reduced throttle? That reduces your climb rate, extends your climb time, reduces cooling air flow and reduces cooling fuel flow.

Try taking off with all three knobs fully forward, leave them there and see what your temps look like.

Looking into my Performance Tables, at WOT / 2700 / Sea Level, fuel flow should be 18.2 gph.

Your EGT number only has meaning relative to peak. On initial climbout, it should be ~200°F ROP. So where does it peak at your reduced power level?

[IgorD]

3 minutes ago, Hank said:

Why climb out at reduced throttle? That reduces your climb rate, extends your climb time, reduces cooling air flow and reduces cooling fuel flow.

Try taking off with all three knobs fully forward, leave them there and see what your temps look like.

Looking into my Performance Tables, at WOT / 2700 / Sea Level, fuel flow should be 18.2 gph.

Hi Hank,

I did try that and my temps quickly jump up to 450 so I reduce power settings and climb rate to whatever I can get at 120 MPH.  That seems to keep them at 430 or so.  My main concern is cruise CHT's back two cylinders are running very hot.  I have searched this forum and seems like everyone is running them at 360-380.  

[Hank]

19 minutes ago, IgorD said:

Hi Hank,

I did try that and my temps quickly jump up to 450 so I reduce power settings and climb rate to whatever I can get at 120 MPH.  That seems to keep them at 430 or so.  My main concern is cruise CHT's back two cylinders are running very hot.  I have searched this forum and seems like everyone is running them at 360-380.  

I climb my C at WOT / 2700 / Vy [100 mph - Altitude], and CHT is usually right at the top of the green stripe. I cruise at Key Number = 46, 50ºF ROP, and there is a needle's-width gap between the CHT needle and top of the green. I'll take a picture tomorrow if I remember.

[Yetti]

Do you have the oil cooler relocation?   I am thinking fuel flow issues.   Maybe smoke test the induction tubes.

[IgorD]

6 minutes ago, Hank said:

I climb my C at WOT / 2700 / Vy [100 mph - Altitude], and CHT is usually right at the top of the green stripe. I cruise at Key Number = 46, 50ºF ROP, and there is a needle's-width gap between the CHT needle and top of the green. I'll take a picture tomorrow if I remember.

My factory gauge stays in the green but my JPI shows high temps.  I tend to trust JPI more then factory gauge from 1968.  Had I not had a engine monitor I probably would not have noticed any abnormalities.  

[IgorD]

5 minutes ago, Yetti said:

Do you have the oil cooler relocation?   I am thinking fuel flow issues.   Maybe smoke test the induction tubes.

Oil cooler is in the regular spot.  I will mention that to my mechanic.  

[Pstone]

If my temps are higher than I like in climb, I pitch for 120 mph.  On a really hot day, 130mph.

[carusoam]

Igor,

What is the max FF you see at WOT….  While you are still close to the ground…

The O360 is probably supposed to get near 18-20gph… (check to be certain)

About 2X what our normal cruise FF numbers are…

FF is a big part of CHT control in the climb…

Airflow is also a big part… if 120mias doesn’t cut it, see what 130mias will do… see if all cylinders improve the same way, or just two…

Summer OATs make air cooling a little bit more challenging than other days…

See if you can down load your JPI data…. The pictures tell a really good story…

Best regards,

-a-