Another Nash 25

[oldengineguy]

Inspired by raveney's build of this engine using steel instead of pricy brass, I decided to have a go. As I do not have silver soldering equipment or skill, I am building the engine as a "bolt it together" I used 3/16 cold rolled for all parts of the crankcase so that screws could be counter sunk and epoxied over, and the inside caulked with JB Weld to seal it up. All fasteners are4-40 except cyl . to block which are 6-32. I made the cyl sleeves of cast iron and will make pistons of the same. The valve blocks are bolted to the cylinders. There is enough space between the valve bores to allow for a 4-40 screw to fasten parts together. Once the head is installed there should be sufficient strength. Lot's of hurdles ahead but hopefully I can work around any silver soldered parts . The crankcase and cylinder flanges are soft soldered. I have enough heat for that.
Onward! Colin

 

[raveney]

Inspired by raveney's build of this engine using steel instead of pricy brass, I decided to have a go. As I do not have silver soldering equipment or skill, I am building the engine as a "bolt it together" I used 3/16 cold rolled for all parts of the crankcase so that screws could be counter sunk and epoxied over, and the inside caulked with JB Weld to seal it up. All fasteners are4-40 except cyl . to block which are 6-32. I made the cyl sleeves of cast iron and will make pistons of the same. The valve blocks are bolted to the cylinders. There is enough space between the valve bores to allow for a 4-40 screw to fasten parts together. Once the head is installed there should be sufficient strength. Lot's of hurdles ahead but hopefully I can work around any silver soldered parts . The crankcase and cylinder flanges are soft soldered. I have enough heat for that.
Onward! Colin

Hi Colin,
that looks amazing! I didn't know you were so far along. Glad you were able to figure out the valve block to cylinder fastening. Keep up the good work, and thank you for the mention

 

[minh-thanh]

So beautiful !

 

[kuhncw]

Colin,

That is very nice work.

Chuck

 

[xander janssen]

Great out of the box thinking.

I have the book of Mr Kelly and once my 2 cylinder is finished, I want to build the snow engine. There is also some silver brazing in that engine.

After hesitating for a long time, I tried a couple of silver brazing parts and now I'm addicted. It opens a new world of making intricate parts out of individual mono-parts instead of painstakingly milling/turning them from a large piece of material, while still being strong.

 

[oldengineguy]

xander: I built the Snow a while back and soft soldered all joints. I have had problems with getting this engine to run well but none of these are related to soldered joints.
Colin

 

[oldengineguy]

I have been building this engine since Nov 23 and following raveney's build log so no need to repeat the same here. I did make some changes to suit materials on hand and lack of silver soldering equipment. Cylinder liners and pistons are cast iron without rings or O-rings. Camshaft brackets are bolted to the crankcase which allows for the cams to be fixed to the shaft as the bearing mounts can be installed from the ends before installing as an assembly. Many old stationary engines had concrete bases so I made mine this way. The steel frame serves as reinforcement for the concrete mix and allows for threaded holes to be bolted from below the finished wooden display base. I had a friend with oxy -acetylene equipment silver solder the heads. I modified the design to solder in the spark plug bushes rather than relying on a press fit. I made an aluminum pulley to drive the water pump and installed the magnets for the Hall sensor in this .The sensor is mounted on a bracket bolted to the rear of the crankcase above the oil drain tube. I am using a Waste Fire Dual CDI system from Roy Sholl with 1/4-32 spark plugs. The engine will run on propane . The first sputters and pops yesterday led to retiming the cams then with a mixer and propane regulator borrowed from another engine, no cooling system and a jury-rigged starter pulley/rope IT RAN!. It amazes me that with this ign system which fires both plugs at each end of every stroke can possibly run. Why does it not burn the fuel at the bottom of the intake stroke? The inspiration to carry on with the rest of the build came with that first run.

 

[GreenTwin]

Very nice engine !
I like that base too.
.

 

[oldengineguy]

After the first run of this engine (post#7) I have had no luck in getting it to sustain a run. Are miniature plugs suitable for propane?

 

[Sprocket]

I have used the miniature plugs with propane and they seem to work fine. I also had a problem getting it running after the first time.
I found the cams had slipped on the camshaft. I ended up putting larger set screws in the cams. #3-48 instead of #2-56
and the larger hex allowed more torque on the screw. As I remember, that took care of the problem, but I haven't run it in a while.
Recheck your valve timing and try a larger set screw. That worked for me.
Doug

 

[oldengineguy]

Thanks Doug : Have rechecked valve timing before and after every failed attempt . Cannot wrap my head around the fact that the plugs fire at the end (bottom) of the intake stroke. Surely this must at least partially ignite the mixture before it is compressed . I agree on the poor method of retaining the cams. Screws are too small. I bolted the cam shaft brackets to the crankcase so can remove the camshaft assembly , slide the brackets off the ends and make larger cam collars to retain cams more securely. Got too much time and effort invested in this project to scrap it but need to take a (sanity) break for a while. I think I will redesign in order to put a proper points /cond./coil ignition system with distributor so that it fires each plug only once in the 4 stroke cycle as Mr. Otto intended.

 

[raveney]

Thanks Doug : Have rechecked valve timing before and after every failed attempt . Cannot wrap my head around the fact that the plugs fire at the end (bottom) of the intake stroke. Surely this must at least partially ignite the mixture before it is compressed . I agree on the poor method of retaining the cams. Screws are too small. I bolted the cam shaft brackets to the crankcase so can remove the camshaft assembly , slide the brackets off the ends and make larger cam collars to retain cams more securely. Got too much time and effort invested in this project to scrap it but need to take a (sanity) break for a while. I think I will redesign in order to put a proper points /cond./coil ignition system with distributor so that it fires each plug only once in the 4 stroke cycle as Mr. Otto intended.

Congratulations on the completion of this engine and the promising signs of life. I read in an earlier post that you didn't use rings? My engine only ran decently after disassembly, inspection and replacing the rings. It may be vastly different with propane, but the ignition seemed to work and it seemed more of fuel distribution problems on my engine. I needed to watch the fuel tank level and adjust the mixture as it decreased. It seemed to like a lot of advance compared to other engines I built and also needed a drill to get it to fire off.

Keep at it as your time and patience allows

 

[oldengineguy]

No rings! Have other engines that run well with cast iron piston and cast iron bore . Lapped together to a close fit has very good seal. Don't think this is the problem. Will get at it again in due course, other things on the go now.