CHT delta T's and Carb type details

[PACERGUY]

Yep my experience is the same when talking to the MSA staff at airshow. I would follow Steve P advice all day long!! Make sure you have a true A1A someone may have switched parts over the years!!! But post the answers to my questions before and after as a training guide to others.
DENNY

[Steve Pierce]

The carburetor is usually overhauled at overhaul. A lot of the got overhauled in 1996-97 when the venturi AD came out. I might try taping off the front cylinder a little at a time and seeing how close you can get it but like I mentioned before, the O-320 has unequal length intake tubes which makes it harder to get temps the same. Remember we didn't have all the instrumentation back in the day that we do now. The 10-5217 was an answer to equaling out fuel distribution by atomizing the fuel better. I would call or email Lycoming. I have found them very helpful over the years.
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[sophistical]

Does anyone know if the sump riser (straight or tapered) matters with the 10-5217 Carb? I believe it used to matter for either the -12 or the -32.

[Steve Pierce]

I will find out.

[Steve Pierce]

This is what I got back from Ken at LyCon:
I think you can run it on eather. It may work better with the straight riser. We mod them but I would bolt it on and see if it works better

[sophistical]

Thank you Steve; I really appreciate it!

I have the straight sump so I just ordered one from ACS. I'm one of those sorry suckers who installed an engine monitor and sees how out of balance things are; primarily on the EGT's so wanted to try something different. I have an O320-A installed today with a -32 and a rebuilt O320-B (also with a straight sump) to install at a future date and I see that the A and B models show up on the SI1523G document from Lycoming. I called and explained the SI to my A&P and he agreed he'd be ok with the install if it's approved by Lycoming.

[PACERGUY]

I have been reading this stuff for years. I think what you want is the top of the carb to match the bottom of the sump. Pretty basic just measure it.
DENNY

[Steve Pierce]

Let us know what you find out.

[sophistical]

I've been running a overhauled 3678-32 carb for roughly 6 years and probably 500 hours. My log books are with my mechanics so I can't be more specific; it was an overhauled or rebuilt unit at the time. I have a straight sump.

The leaning with this carb was never quite right as it just seemed to go lean right away (likely because it was running lean already). This did not have the SB-22 peppered nozzle upgrade that seems to be a good upgrade for the -32 carbs. I installed an engine monitor as preparation to install a 160 HP engine. That's another story; but I'm back to running my 150 hp O320-A with ~1700 hours on it. But .. now I have an engine monitor to tell me all the details I didn't know or worry about before. What you don't know keeps the pocket book full(er).

Now that I have a EDM I see my rear cylinders are running hot and my EGT's are higher than I like. Now I do have a Electroair e-mag and have the Sensenich ground adjustable 82" prop on pin 4; both of which are going to hurt CHTs.

Here is an image from my engine monitor ~2 weeks ago with my 3678-32 carb. This should be full rich.

231117_Power.jpg

Since that flight I added more tape to my rear mounted oil cooler and taped off the front lower half of the front cylinders with aluminum tape to try to drive a little more cooling to the rear cylinders.

Here is a flight Wednesday night; it was pretty warm (I should have removed some of the tape off the oil cooler.) EGTs were right up there about 1550 and #4's CHT didn't go below 400 for the entire 1.5 hr flight so I flew at about 2400 RPM to limit the heat in that cylinder and the oil.
231129_wed.jpg



Here is an image from tonights flight with the 10-5217 Carburetor (similar manifold pressure, full rich.) The 10-5217 does have a "peppered" nozzle that supposedly atomizes the fuel better.
231201_jpi.jpg

Here is an image at a similar RPM; I may have leaned it out in this one. (I have a new cylinder so I'm keeping it rich most of the time.)
231201_2430.jpg

As you can imagine I'm pleased with the change.

[PACERGUY]

I put a pepperbox jet in a 160 hp 0320 and had to drill it out a LOT to get a the engine to run 150 degrees rich of peak. I did help even out CHT's some. With Bendix mags and a Borer 82/43 I usually run about 330-340 with 5 degree spread except # 1 is always 10 degree cooler. I would not use a pepperbox jet unless I had 4 cylinder EGT/CHT they run lean from what I have seen.
DENNY