Major Seal 30cc Build

Basil said:

Lets try this. I sealed the head studs with wellseal which was fine when the engine was cold but as the water temperature increased water started coming up the studs. I don't want to epoxy them in so I am trying high temp silicone and spaced the head up with wood shims and slightly preloaded the studs to take up any play. I also have a plan to join the 2 castings of the head with epoxy and make as one.
Thank you for the kind words. It's been a fun project and I'm sure it wont be the last.

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Hi Basil these things re sent to try us, I may have the same issue with my engine but mine uses cap heads not studs so maybe not as easy to fix as yours.
Hope you get it fixed ok
Paul

Basil, beautiful work. I have a full set of castings, plans and materials sitting ready to go in my Australian workshop, but am presently marooned in New Zealand ( not actually an bad place to be stuck) Did you build the engine without reference to other resources or did you discover additional online resources - apart from this wonderful web site? Once again warmest congratulations. You have set the bar high!

Thank you, So very kind. This is my first model engine build, I took a lot of care with everything, learned a massive amount from this group. Wasn't sure how it would run though. I've wanted to build something like this for many many years. Today I discovered I'd made an error and got the twin coil firing order wrong. I'm used to 1-3-4-2 so I mistakenly placed the wasted spark on cylinder 3 instead of 4, I was getting a number 1 fire but wasted on number 3 at bottom dead center. It runs better now! lol. You've always got to laugh at yourself.

hola me gustaria conseguir los planos del motor para hacerlo yo mismo
donde los podría conseguir

gracias

un saludo

Basil said:

Moving onto the cam! The firing order on the plans is 1243. This is an unusual firing order for a 4 cylinder engine, most everything I've seen is 1342. As I've mentioned before this is going to be installed in a boat and I have decide to have the flywheel at the front which will have a gear and one way bearing for an electric start. All of this messes with the cam lobe positioning not to mention the 1 exhaust, 2 intakes, 1 exhaust and a repeat of the same for port configuration.
To clear this up in my head I decided to CAD it up. I have been 3D printing for about a year now with an Epax X1. CAD is a fantastic tool but I find there is no substitute for holding something in your hand and giving it a good lookover. I machined a flywheel up for another boat a while ago, drew something up in CAD and thought "that should do it". Decided first to 3D print before cutting metal. When in hand it was obvious it was too small for the engine.
Very happy to have something to refer to when getting ready to grind the next set of lobes. I absolutely detest throwing parts in the bin
Some pictures of my 3D resin printing.
Onwards and upwards!

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Regarding your comment on the firing order. There is a correction on the plans from 1243 to 1342. There was also a similar correction in the magazine article covering this engine’s predecessor, the 15cc Seal. I have built a Seal Major, using the David Braid drawings and some castings.

Before boat installation I've been working on the onboard starter.

Nice engine .
Congratulations ! .

Work progressing on the 30cc Seal Major powered boat. Engraved out the flywheel in 2 degree increments, aim is to use a timing light for greater accuracy , working on trying different carbs and also a pressurized oiling system that will spray oil on the connecting rods through jets in the side of the case.
Because of the prop shaft angle at 12 degrees plus the running attitude of the boat I am concerned the front connecting rods will run dry.
The dashed line through the crankcase on image 3413 shows the issue.

Basil said:

Work progressing on the 30cc Seal Major powered boat. Engraved out the flywheel in 2 degree increments, aim is to use a timing light for greater accuracy , working on trying different carbs and also a pressurized oiling system that will spray oil on the connecting rods through jets in the side of the case.
Because of the prop shaft angle at 12 degrees plus the running attitude of the boat I am concerned the front connecting rods will run dry.
The dashed line through the crankcase on image 3413 shows the issue.

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Hi, I am very interested in the oiling system you are going to try as the Seal 15cc in my boat is to plans and is oiling up the spark plugs on the two rear cylinders and no doubt starving the con rods of cylinders 1& 2.
I have been contemplating an oiling system to overcome this . I look forward to seeing your solution!
Regards
Mark

Does this engine have dip-rods into the oil to create splash for lubrication? If so: How about making the dip rods shorter at the rear, and longer at the front, so they dip the same distance into the oil when the engine is in the boat at to correct running trim?
Or is the problem that the rear crank and rod end cap are simply dipping into the oil?- In which case, make a deeper crank case so the oil level is lowered away from the cranks/rod end-cap.
OR - make a guard sort of sump to keep oil away from the rear crank/rod end cap, such that when the engine is started it pushes out most of the oil from the region around the crank/rod-end, effectively lowering the oil just around that crank?
This needs to be properly designed, not just "some parts assembled together with a lot of hope".
Really, this wants to be a dry-sump engine with forced oil through oilways in the crankshaft. As it has ball races for the main bearings, a needle end feed to the crank would be necessary, as well as the crank drillings to carry oil through to each big-end. BUT I guess from the drawing with hashed line for oil level the timing (rear) end of the engine has the prop-shaft attached? - or forward-reverse gearbox?
What arrangement is there to take the reaction thrust from the prop-shaft/screw thrust to the boat hull? - These engine main bearings should not be doing that job I guess?
K2
K2