Calling Franklin 220's with engine monitors

[PCH]

I have a 1972 M-4 220c. The Franklin engine is equipped with a engine monitor. I was wondering what kind of EGTs and CHTs people are getting.

At cruise, I can see EGTs in the 1240 range and CHTs in the mid 200's with a EGT spread of 20 or 30 degrees. I find that EGT spread remarkably good for a normally aspirated 45 year old engine.

Also, has anyone experience with Franklin engine lean of peak operations?

[1:1 Scale]

My Insight engine monitor doesn't give temp numbers for EGT, but I notice that when I lean (just the smooth side of rough running), all the odd cylinders run about 3 bars hotter than the even cylinders in EGT, but pretty even for each side. CHT's are in the low 200's. I think I've only seen one or two get over 300° a handful of times.

The 150 Franklin I had in my Stinson hardly ever got over 200° CHT.

[flyfish1]

I will normally see the mid to high 200s for EGT depending on OAT. When I work it hard in the summer climbing I may hit the 340 mark. I have set my alarm to flash at 350. If I hit that I will do something to bring the temp down , either level off , reduce power or enrich the mixture if possible. I think the max CHT for the Franklin is 380 if I remember correctly. The number 5 CHT is always the lowest. Even though number 6 is at the front end also number 5 is always considerably colder. Maybe its just my engine. As far as the EGTs I cant remember the numbers probably in the 1200 or 1300 range. I'm not to concerned with that number but the spread. At low cruise power settings I will always be within 50 degrees of EGT spread. Glad to hear my engine is similar to yours. When I asked the guys at Southern Aero about normal temps they did not have much to tell me. I guess not that many people running franklins have the monitors. Although they recommend two things for guys running 220 engines, the monitor and the oil filter mod. If you find that all your even or odd cylinders run considerably different you may want to look for an intake leak on the hot side. It seems that the intake gaskets can be a problem with the Franklin.

[Mog]

I’m running a JPI 900 and see CHT’s between mid 200’s up to high 300’s depending on what I am doing. The red line CHT for the Franklin 220 is 390*F. There is usually a pretty big difference front to rear on the cylinders. A new cylinder will burn in at 380-390 and then cool down below 370 after about 10hrs. My engine has about 1000hrs on it and since I reset my spinner, it runs smooth as silk. Power does not appear to be a problem at the moment either so it seems it’s running strong still.

I don’t keep track of my EGTs that well.

[riverbuggy]

My temps run about the same as PCH. That is except for #5. Yesterday at 25 deg. at 3000 ft. CHT finally made it to 199 degrees. I do lean a little at all altitudes, but none of that lean-of-peak stuff. I think it is kind of risky with high compression engine, and such wide variations of temps in a carbureted engine. Basically when I lean I use the guidance in the Franklin Operators manual.

[Mog]

I don’t see how you can be running 199*F CHT. Your oil temp should be at least 170*F. And the green arc for CHT starts at 200*F. You must certainly have an issue with your gauge. Do you have the CHT probe slug installed.

[flyfish1]

My number 5 always runs cold. It is 50-65 degrees colder than the hottest cylinder. I have to work to get my oil temp to the 170 mark. If its colder than 40 I will run a piece of foil tape across the oil cooler. I have a remote oil filter which also acts as a radiator for the oil. A few years ago I was concerned about my number 5 and swapped #3 and #5 cht probes. The numbers stayed consistent(#3 now read low). With a 25 degree OAT I think my number 5 cylinder would be similar. If I get a chance I will download some of my monitor data and verify that.

[maules.com]

Flyfish, check Mogs suggestion. There is an SL or SB re a contact slug of metal to be fitted in #5 CHT probe hole.

[riverbuggy]

Oil temp, and CHT are not necessarily connected. I'm using an E.I. UBG-16.#5 cyl. gets all the cold air. CHT's on all the other cyls. are in the 250* to 270* range. EGT on #5 is similar to all the others. The slug that is referenced in the SL is for original equipment CHT in #4 cyl.

[maules.com]

Oops, regarding the slug position in #4 not #5
However Revision A of 1973, which addresses the different curved crossover baffle needed for better cooling, also moves the slug and CHT probe from #4 to #2 which is the right rear cylinder.

[Mog]

The slug won’t be required for modern long spring loaded probes, but certainly it is for any older systems with a fixed length probe.

I love and hate the franklin, right now I am in love with it since I reseated my spinner and got rid of some bad vibes. Amazing how smooth that engine is when it’s running right.

[Kelly]

On my 220 the #6 is the hottest cht( I think about 20 degrees max). It is also the lowest egt by about the same. usually running about 290-300 cht and 12-1500 egt I think. #6 will go upwards of 320 or so on climb no egt is about 1000 give or take. Rest of the cylinders and exhaust are fairly close in temps. Oil usually runs about 180-200 on hot days. I'm in NW Ontario on floats. I like running the Franklin. Very smooth powerful engine. I have the remote oil filter on as well and change my oil around 25hrs or so.

[1:1 Scale]

If you find that all your even or odd cylinders run considerably different you may want to look for an intake leak on the hot side. It seems that the intake gaskets can be a problem with the Franklin.

The intake gasket on #5 is a pretty consistent leaker, but the others seem to be sealed up pretty well. Going to fix that at annual and get the others to leak too!