proper way to shut down engine

[slam555]

When we did the mags, on my plane, I was told that turning off the mags at idle was bad for the mags, on all other aircraft I've flown you pulled the mixture knob to lean and starved the engine till it quit.
this didn't work on mine, and according to the carb shop it never will.
another A&P says the carb should be set to kill the engine when pulled to idle or pulled fully back, which doesn't make sense, I personally like the stop and the engine just purrs on at 400 rpms. I would be concerned to pull the throttle too far back and end up with a deadstick landing
So what is it, I would like to know I'm on the final repairs and should be soloed by christmas.

[lfries]

If you have a stromberg you’re not going to starve the engine for fuel. The mechanic should research this vs telling you something is wrong. We have two ways to shut the engine off. One is to turn off the mags and the other to shut off the fuel and let the engine run out. My understanding is that if you get a slight RPM increase just before it dies you have a tight induction system.

[3Dreaming]

Shutting off a mag while the engine is running will not cause damage to the magneto. What do you think you are doing when yo do a mag check? Also some checklist for engines that have an idle cut off style mixture include momentarily shutting off the mags to check the ignition switch. There is even an AD for some switches that require this. Shutting down engines like this has been common practice since the 1930's, and probably longer, until the idle cut off type mixtures came along.

A slight rise in RPM right before the engine dies either with the fuel shut off or an idle cut off mixture indicates a proper adjustment of the idle mixture. The procedure is included in many aircraft maintenance manuals for adjusting the carburetor. To big of a rise indicates an overly rich idle mixture.

[Robert Lees]

What's important, Slam, is to understand one* of the reasons why piston engines need a lean mixture to close down. The last thing you want in a shut-down piston engine is unburned fuel in the cylinders, which might wash away the protective oil on the cylinder walls.

Some engines use the mixture control to starve the cylinders of unburned fuel. These use the "lean" mixture so to do.

Our old Strombergs don't have that pleasure. The only way to purge the cylinders of unburned fuel is to smartly open the throttle after the switches (mags) are turned off, with the engine rotating to purge the cylinders of excess fuel.

*it's not the only one.

[slam555]

well that answers that, again can't fully trust the A&P's with the exception of opening the throttle after the mags are turned off I was doing it right.
I really wish one of you guys were in the southwest MO area

[Ragwing nut]

First, find a mechanic familiar with small continental engines. You can shut it off with the mags all day long, no problem. Personally, if I have a stromberg, I will shut the fuel off and let it run out of fuel. This prevents the constant drip of a needle and seat improperly set, or leaking. Mixture on stromberg doe nothing below 4500 density altitude.

[slam555]

yeah I like the idea of shutting off the fuel, but the fuel valve on mine is at my feet, so unless I install a valve at the carb or somewhere between the tank and carb with a remote shut off I'm sol
but with winter here it might happen

[Hank Jarrett]

yeah I like the idea of shutting off the fuel, but the fuel valve on mine is at my feet, so unless I install a valve at the carb or somewhere between the tank and carb with a remote shut off I'm sol
but with winter here it might happen

You need to correct that! The valve is up by the firewall under the tank on a Taylorcraft but there is supposed to be a rod attached to the lever that goes back to the bottom of the instrument panel. In an emergency you NEED that shut off to be available.

[Ragwing nut]

yeah I like the idea of shutting off the fuel, but the fuel valve on mine is at my feet, so unless I install a valve at the carb or somewhere between the tank and carb with a remote shut off I'm sol
but with winter here it might happen

you should have a rod and knob that runs up to the panel. I should have some rods extra

[slam555]

yah mine has the original knob, it runs directly down from the tank, I think I can make a rod assembly that will run up to the dash and turn to open and close it, I kinda have it in the winter to do list, I want to drop the tank and have it worked on, I also don't want any undo stress on the tank fittings don't need anymore leaks.
and for the fuel shut off to kill the engine, I was thinking of a valve right at the carb
does any have a video of the carb removal for the c 85 i can't get to the last nut on the carb, been looking at the 2 nuts on the manifold and the hose connections, but really would like a conversation with someone, 501 519 8066

[NC36061]

Dad was taught to fly by an old timer who was flying before WW2 began, and was a CPTP and civilian B-26 Marauder instructor. He was taught to turn off the mags, throttle full open as the engine shut down, then fuel shut off.

[Scott]

Reminder that there is an AD requiring a guard over the fuel shutoff .

[Hank Jarrett]

Original looked like this but there are several different ways around. fuel clip.jpg

[Ragwing nut]

yah mine has the original knob, it runs directly down from the tank, I think I can make a rod assembly that will run up to the dash and turn to open and close it, I kinda have it in the winter to do list, I want to drop the tank and have it worked on, I also don't want any undo stress on the tank fittings don't need anymore leaks.
and for the fuel shut off to kill the engine, I was thinking of a valve right at the carb
does any have a video of the carb removal for the c 85 i can't get to the last nut on the carb, been looking at the 2 nuts on the manifold and the hose connections, but really would like a conversation with someone, 501 519 8066

that is not a legal modification. It needs to be done per original

[slam555]

I have the original its the stock knob off the tank, I'd like somethin on the dash to turn off the fuel flow