Saving Old Seagulls

Can anyone supply pics of how the water supply on a QB works ?

That's H-A's picture.



Water gets in the block via the water transfer pipe. Some of this water returns through the nut on the right of the picture. This one has a special way for water to pour inside the exhaust, on the outer walls of the inner exhaust. Usually after some use as the way for the water is too slim it blocks and all the water gets out from the main water outlet.

Hope this helps

Ah! I see. What is the length and inside dia. of the 'water spray' pipe ?
I assume Seagull knew what they were doing .... is there a risk of water ingestion through the exhaust port ?
I'm thinking salt water effect on the cylinder.

I don't remember to be a pipe to spray the water inside the exhaust on QBs. It's just a nut with a waterway. Salt water on the outer wall of the inner exhaust is certainly a problem, thus the inner exhaust suffers hard from corrosion. Outer exhaust is not affected. Are you up to a modification?
In my cylinder I will add 15cm pipe which is OK to spray some water in the exhaust.

... In my cylinder I will add 15cm pipe which is OK to spray some water in the exhaust....


That's exactly what I've done with a C100 ... did not change the sound, did not affect the normal water outlet flow. The ID of the pipe is 2.5mm, so I may be a bit small to have any effect.

I have come to the conclusion that an engine will become quieter only if an internal exhaust is fitted, even better if this inner exhaust is wet. I can see only a result in temperature decreasing in the exhaust that can only help.

I suppose if the inside dia. is as large as possible (as it looks like you have done), then there might be some benefit. On the other hand I found the greatest amount of sound comes from the open intake.

If you are happy about drilling holes in a block, why not pair the two holes underneath, drill and tap another hole on the top of the block (as per the 102), so passing the cooling water from the underside/exhaust through to the top of the block.

OK I like drilling and tapping but that would create problems, I should close the outlet to force the water go up, that means that I create a chamber (the one on the side of the block just before the outlet) where water will stand still.

Rob on the QUB's there is an inner exhaust tube see the distorted shiney ring in H-A's pic, Seagull crushed them a little, to prevent the water delivery tube vibrating against the inner exhaust (short shaft inner exhaust tube 12", long shaft 16" ).

What are you trying to do?

Enough for me ... its probably around 2pm (yesterday) in Greece, and 8pm (today) in Western Oz .... but its 11pm here, time for bed.

ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

I think a cautious note should be sounded here.

The water path through the block is a basic one, it's not simply a defined single channel running all round the casting. It's a water bath, and it's filled from the bottom. In the older 102 series it exits from the highest point into the familiar union and pipe that feeds into the exhaust via the two-way union which passes some water into the exhaust and some outside, acting as a telltale. The Centuries just fill up and the water effectively spills out, through the small hole adjacent to the cylinder head.

If this plan to put a water pipe into the exhaust isn't carefully considered, you could end up with a system whereby water is pumped into the block and almost immediately drops out again through the adjacent hole or pipe. This would give little cooling, and there would be no telltale from the block.

It's as well to note that those designs that did utilise water cooled exhausts had more powerful impellers, delivering a greater quantity of water.

The Century impeller has a lower capacity, so care is needed.

Surely, the easiest way to water cool the exhaust as well as keeping a tell tale would be to use the 102 water pipe adaptor that fits on the exhaust and retro fit it to a century exhaust, then attach a water pipe to the adaptor from the water outlet on the century block, simple, it worked with the 102, I think that to alter the flow rate through the cylinder is not really a wise move without any research and surely at lower revs, cooling may stop altogether sooner than it already does I am sure the exhaust note will be quieter right up to the point seizure