Hot tube Adjustment

[Jim Gorter]

More questions for the hot tube experts. I understand about the timing of the engine being linked to the temperature of the hot tube. I have heard that several can adjust the height at which the tube is glowing cherry red. Is the gas orfice adjustable to hit the tube in different spots. I was thinking the tube and the gas orfice were both fixed. Just curious how this is done. Thanks, Jim.

[Greg Downard]

Just like a range burner. The higher you turn up the gas the the hotter the tube will get. The burner opening is at the bottom of the chimney.

[Andrew Mackey]

The hotter you make the tube, the further the heat travels down, and the earlier the engine will fire, Remember - DO NOT look directly into the tube to see the flame USE a mirror! Uhis will save your eyes, and your face and hair, in case of a gas surge or tube failure.
Andrew

[Jim Gorter]

Thanks to Greg and Andrew for the info and the safety tip. Jim

[Harry]

For what it's worth and I am no expert (I never owned a hot tube), Craig Prucha and John Neagley gave me some good text on hot tubes.

You can read it here: http://www.old-engine.com/maghtu.htm

Also, look in on the Similar Threads Chosen at Random shown below.

-- Harry

[Chuck Martin]

Sounds like your still having trouble with the hot tube..

It is difficult to move the hot spot on the tube.
For first start up tweaking, I have "insulated" the very bottom of the tube
with fiberglass electricans tape, it take 3 or 4 layers wrapped around the tube, this works if the engine keeps backfiring when you try to start it. From there you can figure the correct length of tube needed.

Post me a private message if you need some assistance.

[Jim Gorter]

Harry and Chuck, Thanks for the info and tips. Not in trouble yet, but I would like to understand the principles to work things out when trouble does come my way, thanks again, Jim.

[Joel Sanderson]

When I was getting my Reid going I did a lot of experimenting with the hot tube. I ended up putting a little restrictor in the burner pipe just before the chimney. I did this to act as a flame check, because it is what I have on my gas forge. It really helped to prevent the flame from burping back down the pipe where I didn't want it, but it also really changed the shape of the fame. It makes a tall, soft flame with its base at the bottom of the chimney instead of in the pipe, and it doesn't blow out through the air inlet holes at the bottom of the chimney: the flame goes up around the hot tube instead. This taller flame heats the hot tube much more evenly than I was able to get without the restriction, though I have to say the very base of the tube is cooler. I saw immediate improvement with how steadily the engine ran.

My restriction is made of two pieces of 1/16 by 1/2 inch steel with a slot cut (length ways) half way down each. This lets them mate together into a single piece having an (X) cross section.

I think because more of the flame was surrounding the the hot tube and not blowing out the base of the chimney, I was able to turn my burner down and have the same heat on the tube. I don't know how this softer flame would be outside in the wind, though. My engine is indoors where that's not much of an issue.

For all I know everybody does this, but it was a discovery for me.

[W.P.Klein]

I just read John Neagley's piece on hot tubes & in it he mentions the possibility of discussing gasometers. Does anyone know if there is another piece somewhere on them or, if John is listening, can you share with us? Bill Klein

[Graham]

Hi, I run a Scottish SIMPLEX OIL ENGINE, made near Arbroath, Scotland, and installed in its present location in 1908. I have no certain info if it was new then. It is a hot tube ignition engine. The hot tube is fixed in a bulb which is part of the combustion chamber, having a 1.5 inch throat into the cylinder. I believe the purpose of this narrow throat in to control the rate of progress of the flame front from the hot tube via the bulb through the throat to the cylinder. Bore 11 inches, stroke 22 inches.
Fuel: kerosene, (home heating oil), better mixed about 3:1 with diesel oil.
Starting: 1 Heat the tube and bulb, not too hot, perhaps just dull red at the tube closed end. 2 Fill primer cup above the atmospheric air intake valve. 3 Shift the exhaust valve cam follower to the HALF-COMPRESSION CAM. 4 Place a wedge in the rocker arm, holding the exhaust valve open. 5 If starting by hand, find two strong men for the handle. 6 Spin up the flywheels to about 1 turn per 2 secs (guess). 7 Remove the wedge. 8 Then find out if you have NOT over-heated the hot tube for starting purposes or if your two engine-starters are up to scratch. If all well it fires AND goes over compression.
Actually, as I am no longer a youth, I did the unspeakable and put a truck flywheel with starter ring and starter on the 3.75 inch diameter main shaft, and now this spins the engine up to sufficient speed to get it comfortably over TDC on starting with half compression and kerosene fuel.
While it is running up to speed: 1 Return the cam follower to full compression setting. 2 Open and set the water flow to the "third valve", which admits water to the mixture. This both retards and slows the rate of detonation, allowing it to return about 30 hp without pre-ignition or pinking problems.
The engine was run by my father and grandfather before him, and its preservation along with the meal-mill it powers is one of my hobbies.
Hope some-one finds this of interest. Graham

[Roo]

The pics came out on the second one not sure what happened here

[Roo]

Hi Guys,
I have a 1908/09 Austral which is lamp start, you might also want to have a look at the heating coil inside of the head, this is a small coil of thin gauge steel that acts like a wick inside the head and becomes hot and stays hot inside the head.

I have found that this is critical to the starting an on going running of lamp start engines. If the coil is broken or the coils are touching each other effeciency is dramatically decreased.

The best stuff we have found to make these heating coils out of is metal packing strap that is used to hold things on wooden pallets.

As for finding our is the engine is hot enough to start in the instruction book and also told by many other owners spit on the top of the head and if the spit sizzles and evaporates quickly the engine is ready. Ive also seen other guys place a few drops of kero on the head if it vaporises immdeiatly naturally the engine is ready.

The final trick I've found when starting our engine since it is an early one and has no primming port is to suck a gut load of fuel in before starting by holding the valve in and turning it back wards 4 or so revolutions.

I hope this helps

Roo

[bimjy]

Jim, I believe that you can also change the timing by changing to longer or shorter lengths of tube. Jim