Britannia

[Oyster 49]

Rather excessively priced, but other than that seems quite complete.

[Oyster 49]

I've been investigating the lack of smoothness when turning over the powerhead. First I swapped over the cyliners from the swordfish. Not much difference. So I removed one piston and cleaned it up. It was a nice smooth fit in the bore. Looking at the rings, the surface finish is quite rough, rather than the shiny finish you would expect. I'm wonderering if this is due to corrosion. So it looks like I will need to find some new rings

Wanted a set of piston rings for a 1930s Britannia outboard. Same powerhead as the middy.

[Collector Inspector]

Still problems with rings aye?

Do they fit the bore with a reasonable end gap, fit in the ring grooves firmly?

Is the ring width and height uniform around them. Vernier etc?

If above seems ok (Yes, SEEMS OK)then run the engine under a "Light Assembly". By that I mean just the basic gasket at the base. Just a test thingy being easily pulled apart to check what is what inside.

What to do is.

Dry the pistons with metho and get yourself a large indelible/permanent marker (The ones used for graffiti). Totally turn the piston black and leave to dry.

Assemble rings dry to Pistons correctly......yes no pins in piston so get it correct. If the rings have a shiny surface on one face, point that down.

Lightly hone the bores so appear uniform in texture. Take a clear photo of them. Wash them in metho so as completely dry as above.

Get your marker and make the bores black. Let it dry.

Assemble the jugs/ pistons/rings without using ANY lubricant. That may effect how the black marker graffiti wears. You getting the idea?

Start the motor using ether in a can. Down the carb. It will fire and rev instantly. NO fuel mix whatsoever, everything has to be dry.

Keep it running for 10 seconds. (Initial start squirt and maybe two more short squirts for the seconds). It will seem an eternity.....let me know how you felt in detail. Always anguish internally while doing this bit.

Once the smells have gone, pull it apart carefully. The high and low spots, leakage and blow by, thrust area and central running of each side will be totally in your face. Take photos and notes. Proceed from there. Keep your hands clean and dry.

No, you will not hurt it

I await the result aye.

B

[Oyster 49]

Thanks for the advice CI, will be doing a fit check on the rings shortly.

A bit more progress today. I realised that the crank was only sticking when the lower bearing was fitted...a eureka moment. So I removed the con-rods and took the crank out of the crankcase. Yes the crank web, which doubles as a rotary inlet valve was indeed rubbing on the lower bearing/valve body. I ground few thou off the crank web and after 2 goes it now fits and rotates beautifully.

Next I will reassemble and see if it is all a lot more free to rotate now. Fingers crossed

[Stelios_Rjk]

When such problems are finally solved is great relief. Waiting to see the firsts strokes

[Charles uk]

I don't enjoy being a grumpy old schoolmaster & was waiting for someone else to correct the prop mistake, but that doesn't look like it's going to happen, so here goes.

If your Mariner is 1948 or later it will have a 2 : 1 ratio gear box, prior to this a 3 : 1 box was used, only will the pre 1948 Mariners be able to use the Britannia 2, ensign, & Swordfish props.

The Middy (saildrive model) was fitted with a 2.1 : 1 gear box & used an 8 x 7 prop, without knowing the exact reduction ratio of your Mariner it's not possible to know if the Middy gear ratio is the same & this is the sort of size prop you need but I'd hazard a guess & say that a 9.5 x 8 prop would be way too big & would probably bog the motor down.

Search previous posts for the guy who was building the BMB powered canoe he's a very nice chap & might know the location of a suitable prop, can anyone remember his SOS name? Montystubble?

[Oyster 49]

The mariner is an inboard, so it may not have been supplied with a prop?

[Charles uk]

The gentlemean is looking for a prop that will fit this model as he doesn't have access to the 9" diameter reversing prop that was supplied with the Mariner, or the complicated prop shaft that was part of it.

[Oyster 49]

The power head is now back together and all is now correct, after some light fettling of the inlet disc valve. nothing wrong with the rings!Just goes to show check, check and check again.

The bottom end is now stripped down, and so far it all seems in good order.

[Oyster 49]

The lower leg is now back together, all it needed was 70+ years of brush paint removing, a rub down and a repaint. I went for grey enamel as I don't like that flashed over with silver look. The brass casting that sits at the top of the leg separating out water going to and from the powerhead had a soak in a caustic solution for 24 hours and came up nicely.

The gearbox innards were in good order, so just a light clean up required.

[Collector Inspector]

Check and Check again again. Totally the way to do it aye!

I would think as of now that your experience will be able to help others out on this forum if something else crops up.

There is nothing like getting down to basics and doing hard yards with an open mind.

Well done and can not wait for the running vid soon.

Cheers

B

[Stelios_Rjk]

Only until now I understand the way this engine circulate the water! Haven't met anything similar so far.

Close to be ready huh? Nice!

[Oyster 49]

I've now completed the tank and made new fuel and water pipes. I just need to touch up in a couple of places and leave the paint to harden before running. A really enjoyable project.

[Horsley-Anarak]

That is looking very good.

H-A

[Oyster 49]

Just put the tank on and fitted the final new part, a home made fuel tube. Finished! I'll leave it at least a week to let the paint harden, then run it. I've never been able to accurately date it. We know that BMB were taken over by Brockhurst in 1949, so this engine is pre that. The Villiers Mk1 magneto also gives a clue, as we know seagull stopped fitting them just after the war. So this engine is somewhere from mid thirties through to late wartime I suspect.

I've never seen another one of this particular model, does anybody have one? It is basically the same powerhead and exhaust as the Middy, but fitted to an outboard leg. The are a few of the later swordfish engines about, but none of this model.