1898 Nash Two Cylinder Build

[raveney]

Hello All,

I am attempting to build a 1/8 scale replica of an 1898 Nash two cylinder four stroke engine using a beautiful book by Doug Kelley. Doug uses the silver brazed method of fabrication and I needed to improve my skills in that regard.

A very well executed 2021 build is logged by Sprocket on this website, and I followed the material choice of cold rolled steel rather than brass after pricing it out for the crankcase assembly ($50 versus $200+).

I started with the lower crankcase baseplate, and milled the locating channels and fixturing holes in one setup.

Perhaps overkill, but I milled the angled edges of the block webs (center plates) using my shop built angle plate and 11 degrees worth of precision angle blocks. I was tempted to "tack" weld the parts using TIG, but stayed the course and drilled and tapped the 2-56 fixturing screws as Doug outlined in the drawings.

lastly, I screwed it together snugly and tapped it about in the mill vice to ensure squareness and parallelism. I added 3 screws from the baseplate into the webs as it seemed the 0.020" depth locating channels weren't sufficient. I still need to fabricate the flanges and secure them somehow before attempting the brazing.

 

[Sprocket]

It was a very fun build, and for me a project that really broadened my abilities.
Enjoy, and if I can answer any questions, let me know.
Doug

 

[raveney]

It was a very fun build, and for me a project that really broadened my abilities.
Enjoy, and if I can answer any questions, let me know.
Doug

Thank you Doug,
Early in the build, but could you describe the valve timing, firing sequence please?
Also do you just open the crank doors and squirt oil on the crank, or do you partially fill it and allow windage?

 

[raveney]

Got the lower crankcase brazed together yesterday
first i needed to make the bolting flanges and it made sense to make all four parts. Used a 1/4 end mill to make the recess.

I purchased a new acetylene and air torch (turbo Torch) to replace my MAPP gas canister setup. I already had two B tanks so I reasoned it made economical sense to go this route. My significant other didn't concur, but I was called into the plant on a Sunday and the overtime pay convinced her to approve the funding. Victor makes this setup and It is professional grade. I used the A-11 tip and it was very noisy, but heated quickly and used very little gas getting the job done. I flipped the assembly over after brazing the flanges on.

after air cooling the part, I pickled it in citric acid and leak checked it just to verify the quality of the job. It failed so I redid one corner. Maybe I should have sanded the edges again after the pickle bath.

Next I milled off the bottom bolt heads and wet sanded on a granite surface block. Warp was not a problem at all! I am pretty sure it would have bowed if I had TIG welded this instead. The top flanges were then decked using a fly cutter, followed by the front and rear surfaces. It ended up 0.007" taller and 0.012" shorter than the dimensions on the plans, but I can live with that. It is very square and flat and that is a good start.

 

[Sprocket]

Raveney,
I put a quarter inch of oil in the crankcase (iirc) and the crank just barely touched. I started with more
And it was really messy.
I made a drawing of the valve timing, when I go out to the shop I’ll look it up. It is a bit confusing because there is a break in the firing, like
“pop-pop…..pop-pop….” 180 degree twin sound.
I’ll find that drawing in a bit.
Doug

 

[Sprocket]

Raveney,
I found my drawing, and while it worked to explain the valve timing, it wasn't very clear.
This should make it easier:
Cylinder #1,
- first revolution start from TDC
Intake valve is open from 10 to 190 degrees.
both are closed for compression and power.
Spark at 175 degrees
- second revolution
Exhaust valve is open from 140 to 0 degrees.
Cylinder #2 - again start with #1 at TDC and everything is 180 degrees later.
First revolution
Intake is open from 190 to 10 degrees.
Both closed for compression and power.
Spark at 355 degrees
Exhaust open from 320 to 180 degrees.

I used the space between the cam and the lifter roller to measure valve lash, I couldn't see any other way to measure it.

I hope that's clear. The other thing I had a hard time finding was rotation direction. It's on page 54, Full Assembly, figure 2.
From the end opposite the gears, it's clockwise.
Hope that helps,
Doug

 

[oldengineguy]

Raveny : Thanks for the inspiration on the Nash. I have been looking at this engine for some time now but have very little experience and no equipment for brazing or welding', so have put it off. Your use of dado's to locate the centre web and sides will allow me to make a bolt together assembly that I can then epoxy to seal against leaks. I have figured out "work arounds" for other brazed parts but the crankcase had me stumped. Steel will be my choice throughout as brass is very pricey here. Thanks again.
Colin

 

[raveney]

Raveney,
I put a quarter inch of oil in the crankcase (iirc) and the crank just barely touched. I started with more
And it was really messy.
I made a drawing of the valve timing, when I go out to the shop I’ll look it up. It is a bit confusing because there is a break in the firing, like
“pop-pop…..pop-pop….” 180 degree twin sound.
I’ll find that drawing in a bit.
Doug

Thanks Sprocket. The description you gave makes sense now that I drew it out

 

[raveney]

Raveny : Thanks for the inspiration on the Nash. I have been looking at this engine for some time now but have very little experience and no equipment for brazing or welding', so have put it off. Your use of dado's to locate the centre web and sides will allow me to make a bolt together assembly that I can then epoxy to seal against leaks. I have figured out "work arounds" for other brazed parts but the crankcase had me stumped. Steel will be my choice throughout as brass is very pricey here. Thanks again.
Colin

The crankcase should end up very rigid doing as you propose using epoxy and using more screws/bolts instead of just single fixturing screws. Glad that you were able to make use of this posting
Silver brazing, soldering and welding is hard to learn but the additive process makes up for some poor machining sometimes. You can make holes disappear and short pieces longer

 

[kuhncw]

I'm enjoying your build thread. Thanks for posting.

Chuck

 

[raveney]

Good Morning,

UPPER CRANKCASE FABRICATION
finally cooling off down here in Florida, and can spend more time in the garage. I started the upper crankcase using similar methods as used on the lower half.
I chose to braze the camshaft support arms on in the same time rather than "soft solder" them later. Doing this ahead of time drove me to make the ends on the camshaft supports a bit larger to allow some deviation. I might make the gears myself, but using 48 dP cutters I already made.

Find myself using my small WEN horizontal bandsaw with an improvised table more often lately after watching others do so to save time at the mill. If I scrub the parts with gray scotchbrite and acetone, the dykem stays put throughout the steps. The scrap of walnut with the dovetails works very good guiding the parts while keeping ones fingers clear as the small parts heat up considerably. Ignore the holes on the 1/2 thick table, its a dumpster scrap piece that ended up being very close to the size wanted.

Gang drilled many holes to make the crankcase oiling window openings and then side milled out the rest. I have found by experience to stay back away from the desired measurement 0.030" when drilling, and 0.010" when rough milling. Then I climb mill to final measurement.

I kept this mundane "tapping webs" picture to share something safety related. Observe the red cover that is above the electrical outlet in the background. Before this was added, the plugs would work loose just a little and a swarf would occasionally jump there and short the circuit resulting in a loud disturbing pop right when you might least expect it.

Tapped all three webs 2-56 along with the cam support arms. Generous clearance holes were drilled in the side plates and top to permit alignment. Gave a slight chamfer to the edges being brazed to help the silver flow into the joint. Then I prick punched mating surfaces to give a small gap and snugged the 2-56 screws together using a generous swabbing of brown flux.

The brazing went quickly as the last time using the big A-11 tip. But I may have overheated it when holding the tip inside the crankcase attempting to fully braze the middle web and top plate together. It started spitting yellow sparks and a yellowish flame instead of the blue one. The outside was also cherry red back about 3/4 of inch. I let everything cool and soaked the crankcase in citric acid to descale. While it soaked I looked into the tip problem.
Using a bright LED and magnifiers I could see that there is a tri-lobed swirler part down inside and it looked like something behind it. Unscrewed the orifice at the base of the tip and attempted to probe at the mystery gunk from the back using the braze wire. Then I blew it out with air and it seems okay. Thinking the flame traveled back into the tip and was burning some acetylene richly causing soot? We will see... a replacement tip is over $100

Milled and hand filed the screws off, then decked the top, base and sides. Came up short on the width again, but that was no surprise as I made the side panels to 3.750" and flycut them so they were flush. Believe this may be inconsequential, but if not I will compensate on the crankshaft centers.

today I will machine the flanges and screw the two halves together.

 

[Vietti]

Excellent write up. I wouldn't shy away from mig/tig tacking parts before silver soldering. Warping seems minimal and much easier than all those tiny screws. You can tap everything into square after tacking if necessary. ****oos easily cut out with small Dremel abrasive wheel.

 

[raveney]

Thank you for the compliment Vietti!

I sandblasted the two crankcase halves and spotted a few areas that could use filling. They are not weak points as they are joined with brazing filler, but cosmetic so I applied some JB weld and set them aside to cure. Plan A to complete the crankcases on hold.

CYLINDERS
Rummaged through my scrap pile and didn't find any round stock of sufficient diameter or long enough to make the two cylinder water jackets per drawings. I did find 1214L for the sleeve, and a stick of 1-1/2" SCH 80 steel seamless pipe I could use. Revised the plan to accommodate this. Basically the outer water jacket will be brazed to a top and bottom spacer leaving a cooling passage as intended, but all carbon steel. This also eliminated the stepped boring operation inside the jacket as I would needed to make that cutter.

Plan B. Turned the jackets down to size and counterbored the ends to allow spacers to fit loosely. Ended up that 1.412" ID was needed to clean up all variations on the inside and end with a nice clean surface to braze water tight.

Plan B was to use 1" steel pipe for the spacers, but it is 1.375 OD so I found a mystery chunk of metal that was just fat enough and long enough to make the four spacers.

Plan C. I cut them long so they could be trimmed after brazing. Also bored the ID to 1.000" so an alignment bar could be used to keep them concentric while brazing.

After dunking in citric acid bath they appear to be keepers.

 

[raveney]

continuing cylinder water jackets....

Set up on an expandable 1" mandrel and trimmed all four ends to dimensions while cleaning up the excess brazing. Also radiused the step to make it look more "cast-like."
While I was boring the ID to accept the sleeves, I realized that I should make up a plug gauge to test the fit and made an 1.188" brass piece out of a casting slug. I also realized how stupid it was to go through all this trouble of making do with materials that I had rather than just order a 12" piece of 1-3/4 cold rolled steel. I went through around 4-5 carbide inserts and nearly ruined a 9/16" drill making these spacers. I'm pretty sure the material I used up was a magnetic stainless (410?) and work hardened. Committed to it now though and pushed onward.



Made the cylinder bases out off the offcuts of 3/16 steel that I purchased for the crankcase. I chose to do these on the mill rather than the lathe as I needed to drill the four mounting holes anyway.



They measure nearly identical as a set

 

[peterl95124]

Raveney, looking good !!!, and many thanks for posting since the ShelfPetModels "Frisco Twin" is on my wish list but is no longer available and this looks to be a reasonable alternative. when I braze or weld fabricated parts I usually consider them as "castings" that need at least a little bit of machining to square them up !!!, Pete.

 

[raveney]

Raveney, looking good !!!, and many thanks for posting since the ShelfPetModels "Frisco Twin" is on my wish list but is no longer available and this looks to be a reasonable alternative. when I braze or weld fabricated parts I usually consider them as "castings" that need at least a little bit of machining to square them up !!!, Pete.

Hi Pete!
Glad that this is useful to you. It looks to be a very good build and terrific plans and notes to go by. I will likely need help with the ignition when it comes time for that as it references a system that is no longer available (Roy retired). I am getting used to brazing with the new turbo torch setup.

 

[raveney]

Cylinder fabrication continued...

Luckily I had some ribbon solder strips that a retired tool & die maker gave me. First I made all the mounting pads and valve bodies using the mill and a boring head. The valve bodies were a hole split in half after drilling and boring; the locating pads were an interrupted cut......thunk, thunk, thunk...



Fluxed, then clamped the valve bodies to the cylinder jackets and tapped them flush on the granite surface plate. Took a lot of heat with Mr. Turbo Torch (about 4 minutes each) but it went well.



Pickled them and then scribed some center lines for the mounting pads and "soft" silver soldered them in place with the aid of my TIG "welding helpers."



This was all well and good, but they needed to be trued up orthogonal to the center axis on the lathe, and I didn't have the correct size mandrel/arbor. Too expensive to buy AND I only had 2" aluminum on hand; so many many hours later.... I was finished with an 1-3/16" expandable arbor. I made the wedge angles of the cones 1 degree different to see if it tightened and released better (and it did). 4 degree taper in the aluminum body of the arbor and 5 degree on the steel cone nuts. Truing on the lathe was definitely needed as can be seen in the image where the corner would not have sealed well.



I left the pair 0.003" over length so the sleeves and valve guides can be trimmed and wet sanded flush after pressing them in and drilling the ten thousand various holes. Very satisfied with the results so far..

put a very small chamfer on the cylinder mounting bases for Quinn at Blondihacks because that's what separates us from animals Thank you Quinn!

 

[kuhncw]

Very nice work.

 

[Sprocket]

I needed an ignition system for another Doug Kelley model I'm working on and asked Roy for his suggestion. He suggested the Rcexl. It would take a little modification because they are made for larger plugs, and come with braided cables, but otherwise another 2-cylinder CDI system.
Things are looking good!
Doug

 

[Vietti]

Will be interested on how you replace the unsightly braided shielding wire with more appropriate wire.

I thought the cable needed to be grounded so soldered a ground wire to the cables near the CDI unit and it was dead anyway! Any idea on the proper way to replace the shielded wires successfully?

I miss Roy, he provided great service for a long time. I hope he can now find time to work on his own engines.