CHT high temps after new cylinders

[Tom Del Conte]

I just installed 6 new cylinder heads on Lycoming 540io & installed Gami injectors at the same time. We were previously having problems with high CHT's. Since the new cylinders, head #1 goes to 454 deg on takeoff. Also, oil temp is at 233 deg. We've been running full rich through break-in up to about 20 hrs. Mechanics can't seem to figure it out.
Can anyone point me to a cooling expert familiar with a 1969 24-260C?

[MULEFLY]

Baffles... must be tight.

[JIMICS2452]

Check the orientation of the fuel injector nozzle. The air bleed holes should be in the up-down position. If they are front-back ram air can be forced into the injector causing it to go lean, especially on a front cylinder. I know this a a little out in left field, but I had it happen. An old engine guru gave me this advice.

Jim

[Zach Grant L1011jock]

Where are you located? Did the installing mechanic verify ring end gap and grind accordingly (Lyc rings are not exact sized from factory). If ring end gap is too tight, then excess friction will cause hot cyl. New cyl always do run hotter due to tighter tolerances. As they wear in temps tend to come down. I would second the baffle comment. You must use all of the air coming in the front for cooling. It does no good to blow it over/around/through holes that contribute nothing to cooling.
-Zach

[Tom Del Conte]

Thanks to all 3 of you guys who offered advice. I will send all of this info over to the shop who installed the new cylinders and the Gami injectors.
Zach, to answer your question, we are in N. California, Near Livermore (just east of Oakland). My wife is from Indianapolis and we flew to Hendricks Co. last year. We did the Gami recommended lean test last night to provide exact information. We had a high temp of 484 at one point. Outside air temp 90F. Is there any thought that the high temp (484) may have done some permanent damage to the brand new cylinders, rings, pistons, or valves? I have attached the lean test if you care to look it over. Open the attachment to review. The concept of the test is to lean in .2 gph increments and chart EGT & CHTs at each fuel setting. The goal is to determine what temp each cylinder peaks and rolls over to lean.

Also, Any thoughts on Oil Temp getting to 233 degrees?

Thanks
Tom

[skipsouthernsky]

Dear Tom,

I'm not sure what GAMI actually asks you to do, but from your chart my understanding is that you did the leaning test at 24" of manifold pressure and 2400 RPM. I would never lean an engine at that power setting (even for GAMI). My belief is that your high CHT's show why not to lean at that power setting. Hope you didn't do any permanent damage, but hard to tell at this point.

Sincerely,
Skip Dykema

[Jay]

Skip:

I'm curious about why you wouldn't lean at 24" and 2400 RPM? If I didn't lean at that setting, I'd pretty much never lean my turbo PA30!

Jay

[skipsouthernsky]

Dear Jay,

I will yield that point to you. If you want to lean at 24 x 2400 then that is fine with me. Call me conservative. I kind of like my engine(s) running in a real dependable manner. Yes, 24 x 24 is slightly under 75% power and can be as low as 65% power depending on ambient temperature. Especially if you have the instrumentation (JPI, EI) then monitoring CHT's closely, you can lean some and probably do no harm. I personally feel much more comfortable not aggressively leaning unless at a normal cruise which for me is usually 23 x 23 or lower if altitude prevents more MP (normally aspirated).

Just because I am more conservative, doesn't mean that everyone has to be.

On another note, I like to see my CHT's below 400 F. On climb-out I sometimes see a little higher. Maybe 410 or 415 which always stabilizes below 400 F when leveling off and setting cruise power. If I were to see 480 F like Tom has shown, I would be very concerned and definitely not be leaning. I believe that Lycoming has a CHT red-line of 500 F, but I personally don't wish to toy with any CHT near that temperature. Call me conservative again. Consider if Tom didn't have a JPI and went flying merrily on his way, leaning whenever he wanted. Think of what would have been happening in his engine while leaning aggressively at 24 x 24 and not knowing the CHT's were sky high.

So I am sorry to mention what was on my mind. My opinion is strictly my own. Thanks for asking for clarification. I don't plan to be back in this discussion any more. I will let more knowledgeable persons than me give their input.

Sincerely,
Skip Dykema

[Jay]

Thanks Skip, I agree with being conservative, I guess I'm just a bit more liberal. With engines, anyhow.

But I totally agree with you on CHT temps. I keep mine under 400, occasionally I'll see 410 in a climb. Running turbo charged on a hot day that sometimes means "leaning" to 125-150 degrees rich of peak (I have a JPI) with the cowl flaps open. 500 degrees is the red line, and I would be very concerned as well to see 480.

Jay

[Kory Kearney]