7GCAA CHT's

J

jerrywin

New member
I have a 1966 7GCAA with a O-320-A2B. The engine was overhauled by MAttituck and we have about 30 hours SMOH. We also installed a JPI-700 after the overhaul. Since the JPI is new in the aircraft, I don't have any numbers to compare what the engine was doing before the overhaul.

At full power approximately 2650-2700 RPM level flight at about 3000ft MSL, I see 350-360 degrees F on #1, and #2, and 420-430 on #3, and #4.

At about 70% power, the temps drop to 340-350F on #1, and #2, and 390-400F on #3, and #4.

At about 60% power, the temps drop to 330-340F on #1, and #2, and 380 to 385 on #3, and #4.

I am curious if anyone else has a JPI with the O-320 that can compare CHT numbers.

We replaced all of the baffle seal material, with red silicone rubber and have sealed up all of the holes that we can find.

Is this just the nature of the beast due to poor cowl airflow design and/or poor fuel/air distribution of the O-320?

We are still running mineral oil, and the mixture was full rich for all measurements.
 
What kind of cylinders ? You're temps are well within safe limits. I'm sure you have already been told and if you have a JPI I'm sure you noticed the CHT is a good indication of the rings breaking in. Sometimes it can take a while for them to breakin sometimes they never do. on the inital run as the breakin takes places you will actually see the CHT drop as the rings seat. "Spare the rod and spoil the child" to breakin properly the engine needs to be run at least at 75% or higher to get the rings to seat. Some of the cylinders on the market today are extremely hard and this makes breakin to me much harder.


Woodie
N29763
 
Woodie,

As I stated above, the engine was overhauled by Mattituck with new Superior cylinders. I have flown it very hard to be sure that the rings would seat.

I was curious if there are any other 7GCAA owners that have a JPI installed that I can compare CHT's.

I understand that the CHT's are below red line, but the folks at APS recommend keeping CHT's under 400F and try to stay around 380 for normal ops.

The CHT only go above 400 during climbout and that is on a hot Texas day which is 100 degrees or more.
 
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