15cc Seal and 30cc Seal Major

[Jasonb]

Don't you have any 9/64th steel rod? I use that for 4BA and usually get it from EKP saves faffing about turning larger stock down.

[Jo]

EKP are only supplying 3.5mm these days and I normally make all my studs out of 303 so it was about time I set up the running down tool so it can be used 

Jo

P.S. The 3.5mm EN1A is 1/3rd more expensive than the 303   

[gadabout]

Jo,
I ended up with the same issue with the carb hitting even though I left more on the block mounting face so I put in a 3 mm spacer plate between the manifold and the block and all is good now, hopefully there will be no leaks due to the extra plate. had thought about angling the carb but decided I would try the spacer instead. Also gives more spark plug clearance.

cheers

Mark

[Jo]

The Capstan running down tool left the studs with ribs along their shafts if I held the tool in the tailstock and progressed the tool with the tailstock handwheel  So I ended up mounting it on the toolpost and used Mr Silky's saddle powerfeed to cut the 3.6mm diameter shafts.

The process used for cutting the studs was: round the end with a hand file while holding the 4mm bar under power in a collet, run down sufficient 4mm to 3.6mm for the length of the stud, cut off with a small hacksaw -  Do this for all studs to avoid upsetting the running down tool  . Change to a 3.6mm collet to hold the 4BA stud, hand round the unrounded end of the stud with a hand file as before, thread that end with a die, turn round and thread the other end, not forgetting to get rid of any burrs 

I have not yet inserted the studs they are currently just for show. The Cylinder head ones will wait until after the valves guides have had their seats cut and the valves ground in. The threads for the long manifold studs will need to be drilled and tapped shortly.

I am pleased that is over, I can now do something more interesting 

Jo

[b.lindsey]

That's a lot of studs Jo  . Looks like they turned out well.

Bill

[Johnmcc69]

 
Looking good! Going to be a nice pair of engines.

 John

[Dave Otto]

Nice looking parts Jo!

Dave

[Chipmaster]

Hello Jo, what is a capstan lathe running down tool, perhaps it’s a form of box tool, could you show a picture of it please?

Thanks
Andy

[tomherb]

I hesitate to stick my nose in here, as it's been a couple of years, but here goes...  In full-size engines, performance can often (sometimes dramatically) be improved by putting a spacer between the base of the carb and the manifold.  So, I can't see any reason not to do it here, even if it's just to make more room for it to fit up against the side of the engine block.  Also, Jo, I don't know what use, if any you intend for these engines after they are complete and running, but if you intend for them to become the motive power for a boat or other motor vehicle, you might want to look at the spark plug placement in the head.  Even the longer plug in your photo is severely shrouded by the depth of the hole it threads into, which is going to impede the ignition of the fuel.  So, you have a couple of options that I can see -- counterbore the hole on the outside of the engine, to get the plug farther into the cylinder, or make plugs with more reach.  On every commercially-made engine I have ever seen, both spark and glow ignition, large and small, the nose of the plug was flush with the inside surface of the combustion chamber.  On spark ignition engines, the center and ground electrodes protrude into the ignition chamber.

Even if you're not looking to maximize the performance of the engines, unshrouding the spark plugs will make the engines easier to start, and have them run better.

The intervening time since I last followed anything on the board here certainly hasn't degraded your skills, Jo.  Every time I follow one of your threads, I learn a lot, and am also entertained!

[Jo]

Hello Jo, what is a capstan lathe running down tool, perhaps it’s a form of box tool, could you show a picture of it please?

I gave some photos of the tool on reply 149 Andy

I hesitate to stick my nose in here, as it's been a couple of years, but here goes...  In full-size engines, performance can often (sometimes dramatically) be improved by putting a spacer between the base of the carb and the manifold.

On old british motorcycles the heat insulating spacer was added as the heat from the engine would transfer to the carb and cause the petrol to evaporate faster than necessary. In some cases running the engine whilst stationary would mean the engine would splutter to a halt after 5 mins  The Seal and the major are not intended to be put into anything  The challenge is the making of the engine, after that I get bored with them 

I am not going to rush into modifying what is a reliable engine design until I can see all the implications Tom


I started on the next bit today but you will have to wait until there is something worth showing in the way of progress  .

Jo

[Vixen]

Hello Jo

You might be interested in trying a perspex cylinder head on top of the side valve Seal Major. Could be fun and also informative.

Mike

<a href="https://www.youtube.com/watch?v=hKHJR1CylzQ" target="_blank">http://www.youtube.com/watch?v=hKHJR1CylzQ</a>

[Jasonb]

Interesting comments about the spark plugs needing to be flush or protrude into the combustion space in this and Mike's thread. Some of my best running and easiest starting engines have the spark plug in a completely separate chamber linked to the combustion chamber by a small passage, same goes for the hot tube ignition ones too.

Mike I bought a casting set (yes I do occasionally) and that has the option for a glass "head" though not sure if I will fit one as you have to lift the engine up to see it.

<a href="https://www.youtube.com/watch?v=igjZNEqqLHY" target="_blank">http://www.youtube.com/watch?v=igjZNEqqLHY</a>

Jo, Nick has some casting sets available for this at the moment

[Jo]

These are water cooled engines Mike, the water comes in from the cover above the head.

That is an odd looking steam punk style engine JB. Not sure if it is one I would want to import.


A bit of progress..

I marked out the throws on the major crank using the height gauge so I could see where everything needs to go. Then decided I should rough out the flywheel so that was ready to cut the taper when needs be only to realise there is a lot of difference between the existing Seal flywheel and the one I was roughing out for the Major.

Checking the drawings it is clear that the one for the Seal is only 50mm diameter rather than the 63.5mm it should be and it has no groove for the starter or take off belt. The only bit of spare stuff I had of a suitable diameter is hard as  which leaves me with a piece of CI. However CI cannot be run as fast as Steel  I will continue with that bit of horrible stuff and see where I get to

Jo

[Admiral_dk]

Nice to see progress Jo 

Jason - if the engine is running slow enough, it rarely is important where the spark plug is located in the head. I was going to say always, but that will not be true either.
Hot tube ignition is a special case, where the engine need the separate chamber where the tube is connected to and there are a number off old diesels that also has the injector + glow plug in such a chamber.

A too short plug in a high performance engine (and I'm sure this applies to the full size Jupiter too) usually ends up burning a hole in the piston if it will otherwise run OK with the plug, if you run it at full power (or close to) for a while.

[Roger B]

How fast are you expecting the Seal to run? I will check the numbers but I think that a 63.5mm CI flywheel should be good for 15 000 rpm.