PISTON SIZE

[Bill Lawson]

I am looking to build the Snow. A tandem double-acting engine. I am a parts maker with several builds (none running).
I like making parts. The Snow plans use a 1 1/16" dia. bore. Does anyone have any insight as to using a 1.00" bore and pistons? Commercial rings are available that make my task easier.
Thanks,
Bill

 

[oldengineguy]

Bill: I built a Snow a couple of years ago and had the same problem. There was no way I was going to try making rings so opted to go to1 1/8 bore and used commercial rings. Had no problem with the larger bore interfering with bolt holes. Good luck with the build.
Colin

 

[Bill Lawson]

oldengineguy: Thanks for your response. I will adjust my drawings to 1 1/8 bore. Could you advise me of any pitfalls that I may encounter making my build.
Bill

 

[oldengineguy]

Bill: Absolute concentricity and thickness of cylinders ,combustion chambers ,heads etc. is essential otherwise cylinder assemblies will not line up and piston rods will bind, Ask how I know! Use TGP stainless for piston rods .Search rustcollectors build notes on this engine. It's a beauty when you're finished. I got my rings from Debolt, they are on the net.
Colin

 

[stevehuckss396]

Bill!

If you go smaller one thing that comes to mind is the con rod crashing into the bottom of the cylinder with the bore being smaller. I like the snow and have seen many but cannot recall the rod/piston setup so hopefully that wont be an issue. OldGuy's going bigger seems like the safer plan.

 

[Harglo]

I am looking to build the Snow. A tandem double-acting engine. I am a parts maker with several builds (none running).
I like making parts. The Snow plans use a 1 1/16" dia. bore. Does anyone have any insight as to using a 1.00" bore and pistons? Commercial rings are available that make my task easier.
Thanks,
Bill

Make sure going with the larger piston that there is enough clearence of the coolant holes which are very near the cly bore. An yes good alignment of the cly's is a must. I ran mine on propane which getting proper lube was somewhat troubling. Good Luck on the build.
Harvey

 

[oldengineguy]

Harglo: How did you get around the cylinder lubrication problem? I'd like to run on propane. I have not been able to get mine running properly on camp fuel even with water heated inlet. Seems you have to have too much 2 stroke oil or rings seize in piston. Very annoying . There is plenty of clearance for coolant holes with larger bore . It's only.031.5 closer to bore (062 larger bore)
Colin

 

[Lloyd-ss]

I am fairly new at this but have noticed OmniModels as an eBay Store. I believe they were/are based in Champaign IL. They seem to have lots of rings and valves and parts that are model-specific to RC engines. So you have to work backwards from the model number to get the specifications. Is this a reliable source for such items, or are there other, or additional preferred sources. I have noticed several vendors on the HMEM pages, also, which probably deserve our support.
Thanks,
Lloyd

 

[Harglo]

I am looking to build the Snow. A tandem double-acting engine. I am a parts maker with several builds (none running).
I like making parts. The Snow plans use a 1 1/16" dia. bore. Does anyone have any insight as to using a 1.00" bore and pistons? Commercial rings are available that make my task easier.
Thanks,
Bill

Colin
Re the lube using propane with the Snow. I put a small drip oiler on the intake side of the carb the inrush of the vapor seemed to pick up enough of the oil Light weight oil. Given the rapid drawing of the propane the oil didn't have enough time to settle an become a mist. This set up had a bout a 80% success. Oil drip rate just below any smoke on the exhaust. The oiler could probably go just as well just after the carb to the manifold. If you wanted to be sure the rings were lubed open up the drip at intervals an allow some smoke.

 

[Bill Lawson]

Hello again, the Snow cylinder is moving along. Lots of chips, one brain f--t. I wonder if I could epoxy the cylinder liner to the cylinder case with good results instead of silver braze that the print calls for?
Thanks for any help.
Bill

 

[Harglo]

oldengineguy: Thanks for your response. I will adjust my drawings to 1 1/8 bore. Could you advise me of any pitfalls that I may encounter making my build.
Bill

Bill regarding hard soldering the cly an liner if you end up soldering first try a scrap pieces as the print calls for leading steel an 12L4 may not silver braze well. I ued other.
Harvey

 

[Bill Lawson]

Any feelings about epoxy? I really don't like the temp of brazing. I would like to machine to finish and epoxy together.
Bill

 

[kuhncw]

Bill,

Looking at the cylinder cross section in Doug Kelley's book, I think you could seal the liner to the cylinder case with LocTite retaining compound such as 609.

I used LocTite to seal the liners into the cylinder block when I built a Silver Bullet and have had no problems.

Chuck

 

[methuselah1]

Another traditional method is the (almost forgotten) rust joint, which is impervious to heat. Prepare a solution of ammonium chloride (sal ammoniac) and coat the sealing surfaces. Assemble everything, then wait a couple of days. That might be cheaper than loctite. You should be able to buy a block at the hardware shop- it's sold for cleaning the tips of soldering irons.

-Andrew UK

 

[Rocket Man]

I am looking to build the Snow. A tandem double-acting engine. I am a parts maker with several builds (none running).
I like making parts. The Snow plans use a 1 1/16" dia. bore. Does anyone have any insight as to using a 1.00" bore and pistons? Commercial rings are available that make my task easier.
Thanks,
Bill

I am getting old and time is very short, I am not wasting my time building piston rings. Buy a junk weed eater at the scrap metal yard or yard sale, use the piston & rings to build an engine. Make the engine bore fit the piston & rings. .002" clearance is plenty for an engine like this. It would take me a week to make a piston of equal weight as a factory made piston. Weight a factory piston on gram scales then try to make the same weight it is slow work. Factory pistons are die cast or stamped 1 every 7 seconds. I worked in a die cast factory for 20 years. If you live near me I can give you several factory pistons and a weed eater engine.

 

[oldengineguy]

Rocketman: the Snow is a double acting engine so a pre-made piston will not work. It has to be a solid piston flat on both sides like a steam engine. I tried epoxy and could not get good result. Did not have silver solder equipment at the time, so used soft solder. Pre heated parts in B.B.Q. then propane torch. The cylinder is never going to get hot enough to melt the solder(400F) and it is a zero pressure cooling system joint. Loctite would probably work also.
Colin

 

[Steamchick]

Hi Bill,
Re: your post "I wonder if I could epoxy the cylinder liner to the cylinder case with good results instead of silver braze that the print calls for?" - prompts me to ask "what shear strength epoxy?" - and the same goes for the silver solder. I suggest you check the shear strength of the silver solder and epoxy at the max temperature expected of the joint... (Hot enough to boil water = 100deg.C, Hot enough to smoke-off oil = 200deg.C).: tensile strength of silver braze alloys is 40,000-70,000 psi. Epoxy Physical Properties ; Tensile Strength (PSI), 7,846, 7,320 ; = 1/6th that of silver brazing at room temperature.
e.g.
Master Bond EP33 High Temperature and Thermal Cycling Resistant Epoxy:
Master Bond Polymer Adhesive EP33 is a unique room temperature curing two component epoxy adhesive for high temperature bonding applications. It is formulated to cure at room temperature or more rapidly at elevated temperatures. Master Bond Polymer Adhesive EP33 produces high strength bonds whose strength is maintained even after long exposures to temperatures in the 400-450°F range. (I.E. around 200deg.C).

If only 100C, I guess epoxy will suffice, but if >200C then you probably need the silver solder. Also consider forces involved... as you don't want a weaker joint to move/creep during service, and either wear badly or destroy the engine?
I have bronze brazed and re-bored a cast-iron engine cylinder that ran successfully afterwards, but would not expect an "organic material" to withstand the stresses and temperatures involved, even though epoxies have good strength at room temperature. All glues deteriorate their strength with age, epoxies and polyurethanes included. It is just that they age differently with temperature and stress, so seldom last the lifetime of a metal repair.
As to "loctite" and other anaerobic sealants: they are good for maybe just over 300C sort of limit, if you select a high temperature grade. Probably why Colin had success with this but not epoxy?
SONLOK® High-Temperature Resistance Adhesives are specifically formulated for applications that are continuously operating in high temperatures, even up to 340°C without degradation.
K2

 

[xander janssen]

I had a look at the drawings and if I m correct, the bond is "only" holding the cooling water inside. All forces due to combustion are mechanically taken by bolt, nuts, seals and interlocking parts. As the pressure on the cooling water is relative low, I expect that epoxy will work.

I would like to build this same engine in (near) future i.e. start within the next 3 years . For now I forsee that I will use epoxy/loctite for this joint.

 

[Steamchick]

Hi Xander, I have seen engine blocks where cylinder liners have moved, because they were not correctly "clamped" by the cylinder head/gasket. All be it that was in the 1960s, repairing diesel engines from trucks. The piston frictional forces (when there is insufficient restraint) causes the liners to try and oscillate up and down in the water jacket. The water didn't do a very good job of holding the liners in place when not clamped by the head gasket.
But I don't know your configuration. Can you post a section drawing of the assembly?
K2

 

[Steamchick]

I could not open the drawings here as I do not have an adequate computer for Solidworks.
https://thebloughs.net/metalworking/snow-model-engine/K2