450D operation?

thdrduck

Member
Buddy has a 450D (not running) and we were talking about how it works. I'm trying to figure out what they did in the head to be able to start on gas and switch to diesel. My buddy says it's just a low compression diesel, I don't see how you could have enough compression to burn diesel and not pre detonate gas. So what is up with this mythical beast?
 
The lever on left side you pull that to start on gas it opens a
small valve in the head drops the comp runs on gas get it
warm push lever ahead and pull throttle down a bit and your
now on diesel
 
It has a set [1 per piston] of decompression valves,so it can turn over, and get it started on gas, you really don't want a gas running on a 15 to 1 compression ratio either, that would really turn over hard. If it roll's grey smoke out of it as it turns over ,or first starts, to me that's the diesel not being completely turned off That's is a easy adjustment to.You should really have a experienced IHC diesel guy there to walk you thru it, and when u change engine oil , also change the oil,in reservoir ,in the Injection pump.
 
The other answers are right, and I'll add to
them to help you better understand how it
works.

As mentioned, the selector lever on the left
side switches the engine from gas to diesel.

When it is put in the gas position, like
mentioned below, it opens a small valve in each
cylinder that bleeds off some compression. It
also activates a switch in the intake manifold
that supplies power to the ignition coil, and
releases the float in the carburetor to let
gasoline run into the carb.

The carb on these does not have a throttle to
control engine speed. It is meant to only run
at a fast idle to get the engine warm enough to
fire on diesel. There is a choke for cold
starting.

The throttle lever on the tractor controls the
injection pump like on any diesel, except for
the fact that at it's lowest setting it
effectively shuts the diesel fuel off
completely.

After the engine has started and run a minute
or two on gas, the selector lever is pulled to
diesel while at the same time the throttle
lever is moved to allow diesel fuel to be
injected. When the selector lever is pulled to
the diesel position, it closes the starting gas
valves in the head for higher compression,
shuts off electrical power to the coil(or
grounds the magneto if so equipped), and pushes
the carb float down to shut off the gasoline
flow.

Then the tractor is run on diesel until you
are ready to shut it down. These MUST be
allowed to idle for several minutes to cool
down after use. Some people switch back to gas
to cool down, some just idle at the slowest
speed on diesel, and then close the throttle to
kill the engine.
 
As noted, the compression release provides about 5 to one compression for gas starting and warm up.
The compression relief valves allow compression pressure to go into a separate compression chamber with the spark plug in it. When in Gasoline mode, the intake manifold air intake is closed to raw air, and a separate runner system sucks through the small carburetor. There is no "throttle" in the carb, it is small enough to run at a fixed opening. When switched to diesel after about one minute when in summer, or 3 minutes in winter, the air is redirected to pure air, and the mag or points/coil is shut off, and the compression reliev valves are shut. Jim
 
Thanks guys, I figured there must be something going on to reduce the compression. Someone mentioned these are about 15:1?
 
Remember early MD tractors were between 14 and 15 to one. and 450 between 16 and 17 to one.
If tractor data got something correct I will apologize.
 

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