Twin cylinder open crank marine engine

fourstroke · Feb 13, 2016

Well I decided to go ahead and increase the size of the ports, the next size up of brass tube I had was 1/4" od. So the casting was set up and the passages drilled and reamed
My thinking is this, if I need to reduce the size of the passages I can just slide in a smaller diameter tube, but there is no way of increasing the size once it is all soldered up.

The first couple of pics show the head with pieces of brass tube set up ready to be fluxed and soldered. Because I increased the size of tube I had to make a little undercut under each one to provide clearance for the water to pass
The next two pics show the end result after the tubes are soldered and the flux cleaned off.

The ledge for the two rings to sit on was fluxed and both of them placed into position and solder run around the inner and outer edge the next pic shows the result. Finally the casting was clamped to the mill and the base skimmed, a nice ring of solder is just visible in the pics

The final pic shows the casting being checked for leaks, I filled the water space using a small syringe and have set it on some absorbent paper to see if any water makes it way out, so far, so good

Thanks to all who helped with advice regarding the ports

Off now to shout at the tv while Scotland (probably) suffer another glorious defeat to Wales at the rugby

Regards

Dougie

Brian Rupnow · Feb 13, 2016

Very nice build.--I am following with interest.---Brian

fourstroke · Feb 14, 2016

Well. I was right about the rugby

Leaving the head filled with water overnight showed there were no leaks through the soldered joints
The next stage was to drill and ream the stud holes 5/32" for the brass sleeves. Little lengths of tube were cut and I decided that rather than solder them into place and risk upseting the previous joints I would glue them in place with loctite
The first two pics show the tubes in place. The casting was left in the warm for a couple of hours before the excess was trimmed. The base was sanded smooth and the tops of the bolting bosses were filed flat. I also drilled and tapped the water outlet hole
The final pic in this set shows the head set up with a litte length of 1/4" copper tube screwed into the outlet to provide a little "head" of water while the last leak test takes place

Regards

Dougie

kuhncw · Feb 14, 2016

Dougie,

Nice work on the cylinder head and the water cooling passages.

Did you silver solder (silver braze) the joints or did you use soft solder?

Chuck

fourstroke · Feb 14, 2016

Hi Chuck, Thanks for your comments
Everything was soft soldered, there wasnt much chance of anything moving or slipping during the various operations so I didnt see the benefit of silver solder and it made things much simpler
Regards
Dougie

fourstroke · Feb 20, 2016

With the head water passages complete I now needed to set the positions of the upper and lower cam drive shaft bush

The lower hole in the base was made a little oversize for the bush and the position set by meshing the two gears with some cigarette paper between, to give some clearance, and glueing the bush into its hole. Once the glue set the top bearings were positioned, covered with tipex to stop the solder flowing where I didn't want it to go, and soft soldered into place.

The casting was then mounted onto the jig and the centre height of the drive gear transfered onto the uprights where the camshaft will be supported. After squaring everything up the two gears were meshed, again with some paper between, and the position of the first bearing hole marked. The first hole was centred, drilled and reamed 10mm. This might seem a bit large for a 3/16" camshaft but they need to be this size to allow the cams, which will be fixed to the shaft, to pass through.

A home made centre drill made from a piece of 10mm silver steel was used to transfer the centre onto the mid upright, this was again drilled and reamed 10mm. The final upright, the one furthest from the drive gears, just needed a 3/16" hole to support the shaft, once it was centered the same way as the others it was drilled 5/32" using a long worm drill. Later the casting will be upended and the hole reamed to 3/16"
The casting was re positioned to bring the rocker arm pillars under the mill and the holes for the rocker pivots drilled 5/32"

More pics in the next post

Any comments, suggestions or ideas welcome

regards

Dougie

fourstroke · Feb 20, 2016

I now made a start on the eccentric drive that will power the water pump.

I decided on a stroke of 3/8" so set some brass in the three jaw chuck with a packing piece under one of the jaws to throw the bar off centre and give me the offset I needed. Once the hole was drilled and reamed 3/16" the packing was removed and the drive turned to 14mm. A piece of bronze was bored to match the drive and parted off, this was filed to shape and the two parts are shown in the third pic in this series

The last three pics show the various parts assembled to see how things were looking and to check everything rotated freely

Regards

Dougie

deverett · Feb 21, 2016

fourstroke said:
Off now to shout at the tv while Scotland (probably) suffer another glorious defeat to Wales at the rugby

Regards

Dougie

And then Ireland!

By the way, Good work on the engine.

Dave
The Emerald Isle

fourstroke · Feb 21, 2016

Yes, probably.
But, as celts, we both know there's only one match that needs to be won to numb the pain of all other defeats, we didn't manage it this time but good luck on the 27th
Regards
Dougie

bmac2 · Feb 24, 2016

OK. Im going to assume you guys are talking about the Six Nations Championship? I had to do a quick search on the infomercial super highway and all I can say is H@LY CR#P good thing its on TV. The tickets for the England vs Wales match on the 12 are starting at £550!

Thats like $1061 Canadian!
Oh ya . . . . Dougie, the engine is looking great Thm:. . . . . I got to go splash some cold water on my head . . . . . £550!

deverett · Feb 24, 2016

bmac2 said:
OK. Im going to assume you guys are talking about the Six Nations Championship? I had to do a quick search on the infomercial super highway and all I can say is H@LY CR#P good thing its on TV. The tickets for the England vs Wales match on the 12 are starting at £550! Thats like $1061 Canadian!
Oh ya . . . . Dougie, the engine is looking great Thm:. . . . . I got to go splash some cold water on my head . . . . . £550!

You're right - a bit expensive for a ticket, but they take their rugby seriously over there.

Dave
The Emerald Isle

fourstroke · Feb 24, 2016

Hi
I decided that next I would complete the water pump
This series of pics show the various pieces being soldered together, silver solder for the first parts and then soft solder for the final assembly. Its a simple two ball valve, the 1/4" street elbow in the bottom for the inlet had a perfect size hole for a 3/16" stainless ball and all it took was a clout with a hammer to form the seat

The base was first with a high melting point solder along with the right angled outlet on the valve section. The main body was turned to size and then soldered with some easyflo to the base section
Lastly the valve section was joined to the body with soft solder, the pics show the parts held together with steel wire on the perforated board
A screwed plug with a square head was made to seal the top opening and the rear of the barrel sealed with a brass plug

The final pics show things set into position to check rotation

Regards

Dougie

fourstroke · Mar 2, 2016

With things on the base casting pretty much complete, I decided to make the rockers

First the head casting was bolted to the mill table and the rocker posts trimmed each side to square them up. Next the basic shape of the rockers was marked out onto some 3mm steel plate, the pivot hole was drilled 15/64" and the lower edges cut and filed to shape.The top edge was left flat to give me a level surface to sit the rocker on while it was silver soldered together

At this stage the tips were case hardened, once that was complete the pivot hole was reamed 1/4" and two 1/4" pivots were drilled and reamed 3/16". Two slices of 1/4" steel were drilled and tapped 6BA for the adjusting screws.

The next pic shows the kit of parts to make two rockers, followed by one set tippexed, fluxed and held to the perforated board with wire to silver solder everything together.

The last pic shows two of the four rockers complete apart from the brass bushes in the pivots to bring the internal size to 5/32".
Now they just need a good clean with a wire brush

Regards

Dougie

fourstroke · Mar 9, 2016

As I mentioned in a post in my last engine build, I can get carried away thinking about so many things to add to a project, that it never gets finished. I fall very much on the " its not the destination, its the journey", side of the fence.

And so it has been with this engine, I spent days dreaming up a flyball governor, position, mounting etc, a nice addition but not what I need to be doing

With that in mind I am trying to concentrate on things that the engine cant do without and with this design being a 180 deg opposed crank it needs a distributor. I started last Saturday thinking it would take the weekend, three prototypes later I think I got the final design finished tonight

The first pic shows the backplate/mounting plate on the left along with the register for the distributor body on the right, both of these are made from tufnol, as is the rest of the unit. The centre holes are drilled and tapped 6BA at this point to get the centres lined up while the two were glued together with araldite
Once this set the centre hole was drilled 5/32" and the part mounted on the camshaft while the holes for the securing bolts were drilled and tapped. The centre hole was opened up to 11/64" for clearance

Next is a pic of the beginning of the body, a piece of tufnol was held on a mandrel while the body was turned to size, 14mm. It was held in the three jaw and bored to internal size of 11mm to match the register. The next pic shows the three main components, mount, rotor and body. The body was set in the rotary table while the holes for the terminals were drilled at 90deg apart

The (third attempt) at the rotor is shown with its terminals in place, the screws are 10BA, they meet internally to make electrical contact and carry the spark from the centre to the edge, the following pic shows the body with two 4mm tufnol inserts to hold the 10BA screws for the spark plug leads

The last pics show the assembly on the engine, to set it up I screwed in each spark plug terminal in turn till I got contiuity on my multimeter from the lead to the centre 8BA terminal. I then backed each one off half a turn to set the gap and locked the terminals in position, the centre screw on the rotor is not countersunk competely to let it stand very slightly proud of the rotor. The rotor is held to the camshaft by a 10BA grub screw.

As always, enjoy
Comments, suggestions or advice welcome
Dougie

fourstroke · Mar 14, 2016

Next in the grand scheme of things was the dummy magneto that holds the hall sensor and the rotor fitted with two magnets to supply the ignition

The first couple of pics show the basic body shape cut from a block of aluminium, at this point its a little overwidth and still has the top to be rounded, the following two pics show the body at final width of 17mm and the top rounded off, the shaft will be 1/8" dia and runs in some brass bearings made from k&s tubing

After checking the angle of the timing chain between the camshaft and the magneto the head casting was set up on the mill table to cut the slot for the chain to run through. The rotor was turned from brass, set up in the rotary table and the two holes for the 2mm dia magnets were drilled. A bracket for the magneto to sit on was silver soldered from three peices of 1/16" steel, slots were cut into it to give me some adjustment horizontaly and vertically
Everything was screwed into place to check clearance and slack on the chain

Finally there are a couple of pics of the magneto with all the internals fitted, the brass lever will hold the hall sensor in place above the rotor and can pivot to advance or retard the ignition

Regards

Dougie

fourstroke · Mar 23, 2016

I was toying with the idea of making an "automatic" type of carb for this engine, along the lines of the one I made for the last build. But, I was having a bit of difficulty fitting the designs I had in the space I wanted. So, after some thought, and advice from seadragonfoundry on here I decided just to go with a "standard" needle valve carb.

The first few pics show the start of the upper manifold that will split the intake to both cylinders. It started as a short length of 1/2" sq brass, a flat was filed onto one corner and a small hole drilled diagonally through, this was superglued to the head casting and the hole spotted through and opened up to tapping size for 6BA.
The block was held in the vice and thefront of the hole opened up to 3/16" for a spigot that will be silver soldered in later. The transfer holes for the fuel were marked on the sides and base then drilled 3/16". The top was rounded on the belt sander and polished smooth.

After a couple of failed attempts to build up the main body I finally settled on a brass pipe elbow that had the right size and perfect flare. The unwanted hose barb and threaded portion were cut off and a couple of filler pieces turned and fitted to the insides then silver soldered into place and drilled 7/32".

A small groove was cut on one side of the front flare to take a length of 3/16" brass drilled and tapped 8BA, this was silver soldered into place and will hold the shutter to the body. The jet is shown next, the small thread is 6BA and the large is 3/16 x 40 for the fuel union
The next pic shows the main body with the jet and needle valve in place and the front has been opened up with a home made taper D bit.
There a couple of pics missing where my camera battery went flat, this was when the upper manifold and body were joined by a length of 5/16" brass tube and a backplate was shaped and soft soldered to the back of the body.

Finally there are some pics of the completed carb assembly and some of it fitted to the engine

Regards

Dougie

bmac2 · Mar 23, 2016

Hi Dougie
The engine looks to be coming along great. Thats a very cool looking carb, matches the feel of the engine perfectly.
Thanks for posting

fourstroke · Mar 27, 2016

With the carb sorted I moved to the exhaust

The first pic shows a piece of 12 x 3mm stainless steel marked up with the shape of the flanges and the holes for the exhaust and holding bolts drilled. I shaped the outer edges of the flange on the sander and opened up the exhaust holes to 5/16", this piece was then centred onto the head casting and superglued in place while the holes for the studs were drilled and then tapped 6BA
Two pieces of 5/16" stainless tube were bent into right angles and while the flanges were still in one peice I sanded the longer ends till they met in the middle with a close fit. A scrap piece of steel was drilled and tapped 6BA to match the hole centres of the flanges, these were then split into seperate pieces and rounded off as I wouldnt be able to get to the inside faces with my sander once they were soldered, the next pic shows the tubes held in the flanges while the centre section was silver soldered. This sub assembly was then removed from the scrap steel and the flanges silver soldered to the tubes

The vertical section is made from 10mm stainless tube, one end was ground to a close fit over the two previous sections and the centre of the two pipes ground out also. The twin section was screwed into position on the engine and the vertical section held in place with some wire, this joint was then tipexed, fluxed and silver soldered into place once I was happy it was straight and vertical

Regards

Dougie

fourstroke · Mar 27, 2016

Now I needed a fuel tank.

I didnt have any tube of a suitable size so I rolled my own
I started with a rectangle of brass long enough to give me a finished diameter of 30mm. The first pic shows the flat brass sheet and the second shows the tube after rolling. The overlap was trimmed with a dremel and a cutoff disc, the ends were annealed and formed over a steel bar to round the long seam.

The join was tippexed and soft soldered along its length. A filler neck was turned and threaded 3/8" x 32 along with a flange for the outlet, the next pic shows the filler, outlet flange and two lugs for mounting the tanh to the rear of the engine soft soldered into place, the ends have also had brass discs soldered into place
The last pics in this set show the tank in position on the rear of the engine

Regards

Dougie

fourstroke · Mar 27, 2016

This set of pics show the little fuel shutoff valve I made along with some views of the engine with all the latest additions fitted

The body is made from 6mm brass rod. A small piece was turned down to 7/32" and threaded to match the fuel outlet flange, a cross hole was drilled into another length of brass and silver soldered into place

The body was cut to 30mm overall length, drilled 2mm through and then opened up to 5/32" with a slot drill 20mm deep, this gave me a flat face for the valve spindle to seat onto, The inside was tapped 3/16 " x 40, 14mm deep
The next pic shows the various components of the assembly. The body, glands and union nuts all from brass and the spindle and handle from stainless steel followed by the parts all assembled
Lastly are some views of the progress

Regards

Dougie