I’ve been doing some research surrounding power settings in the 421 and there doesn’t seem to be a good consensus. My question pertains especially to the climb. Do you lean your 421 out in the climb or leave it full rich until cruise? What is your procedure based on? Interested to try some different climb and cruise power settings out

In a 421B reduce power to 32” and 1800 rpm, mixture full rich in the climb. May change power settings for cruise, lean to about 1550 TIT. Why? That’s what I was taught.

I have more experience with the Aerostar. I climb full throttle, max rpm and full rich. Others reduce power and lean in the climb, that may save fuel at the expense of time. I don’t think it is a huge difference. I have tried multiple methods.

I climb at 35"/1900 and 31.5 gph. This puts TIT 1450-1475 & CHT's are cool.

Cruise is 32.5"/1800 and 22.5 gph ROP or 17-17.5 gph LOP.

I pull back to 32” and 1900 on Rs (no changes till 1,000’). Then lean to max of 1500 for cooling. I tried different settings too and usually us those settings to 16K and above. I routinely cruise at1550-1600. OK, I’m not buying the gas!
Had a buddy who cruised routinely at 1650 He wound up buying a set of cylinders!

Let us know if something else works better for you.

I have run one set of engines out to TBO and I am working on my second set of new engines.

Max power to 1,000 AGL with 45/46 gallons per side. TIT’s on TO should be 1500 or less.

Climb 32.5 and 1900 (top of the green ). FF should then be 31 to 32 GPH in the climb and all Cylinder head temps below 380 this is important. Mine run 285 to 350 in the climb. TIT’s in the climb should be 1400 to 1450.

For cruise my favorite power setting is 31/1700 and TIT’s 1500 to 1550 and 19.5 GPH per side. Standard day 15,000 that’s 61% power so I can run right at peak. This gives me about 207 KTS TAS.

Jerry, what is peak for you? I hear this strategy from time to time but what is your peak based on? We’ve never peaked out the 421 or run it LOP. We don’t have the RAM engines so top of green is 32.5. We usually climb at 32.5/1900 but we don’t touch the mixtures. Should we be leaning in climb? Thanks all for the responses!

I generally cruise at 32.5 and 1800. At 15k I doubt I would tas 205 at these settings. Gerald is your plane fast, or mine slow? I have hubcaps, but quite a few antennas including a hf wire from nose to tail.

Jerry, what is peak for you? I hear this strategy from time to time but what is your peak based on? We’ve never peaked out the 421 or run it LOP. We don’t have the RAM engines so top of green is 32.5. We usually climb at 32.5/1900 but we don’t touch the mixtures. Should we be leaning in climb? Thanks all for the responses!

I generally cruise at 32.5 and 1800. At 15k I doubt I would tas 205 at these settings. Gerald is your plane fast, or mine slow? I have hubcaps, but quite a few antennas including a hf wire from nose to tail.

You should not be leaning for the climb. I can't remember the exact scenario as it's been quite a few years since I heard the explanation, but something changes in the fuel servo at the forward throttle position increasing the fuel scheduled.

Hopefully someone on here knows the full explanation for the reason. I was taught 25 years by a gentleman previously from a large OH shop that knew the G/TSIO engines inside and out. He was a Maintenance Manager for a 135 operator with over 30 GTSIO engines...

Do Not lean for TO, but in climb the throttle is not full forward anyway, it’s pulled back to 32.5 inches.
If you have a good engine monitor and gami’s you can lean in the climb. Just don’t go over 1450 TIT and keep hottest CHT below 380.

It’s an OWT you can’t lean in climb or run LOP.

I don’t have an engine monitor, just the analog tit and Shadin fuel flow. Lean to 1400-1450 in the climb and cht’s (3in1 gauge reading) are always below 350.

That’s ok, but I would install a good engine monitor like the G4 at your earliest convenience.

RAM Produces a really good recommended power settings chart. Just toss it in the cockpit. I used it all the time when we had a 421C

I always climbed at 35” not 32.5”. No magic about 32.5 except that it’s the “top of the green”, and I never have gotten an explanation about why there’s even a green band on the MP gauge. There’s no engine limitation that equates to the 32.5...

RAM had some silly STC which repainted the MP gauge and magically “allowed” you to climb at 35”... I’ll give them credit for finding people dumb enough to pay them for the STC, but the airplane didn’t know it had a differently marked MP gauge.

I generally did not lean in the climb but sometimes would bring the red levers back a bit if the engine was clearly running too rich (you can tell when the GTSIOs get too rich by sound). With an engine monitor (and the knowledge to read it) there’s no reason not to lean a little in climb.

Robert