1962 Seacraft

[DaveD]

Perhaps the water inlets to the exhaust manifold are a little to close to the exhaust ports/head?

[screwit]

they need to be set lower down the manifold Craig, with the tubes traveling down as far as possible ., My boat with the extractors on has the tubes entre about 350 to 400 mm down from the ports in the collectors and with a pin hole from a weld 70 mm from the exhaust port on number 0ne, it still leaks water. You need to run the boat out of the water to empty all the water out of the hoses before you park it up. you must have condensation sitting there at the port as it cools .

[WoodRay]

Thanks Dave & Ross.
Yep though that maybe it too but still trying to understand the theory of it as to why it would blow the water back out. Maybe its expansion of the water when it turns to steam which is about 1:1600 and this might happen closest to the exhaust port. But then again the water is coming out as water not steam.....why is it so.....
I was thinking of reworking the engine pipes to have two 1/2" inlets well down the pipes when I get the grey done. Ross I do think I have a slight high point at the exit area of the engine pipe where it goes over a rib so there might be water collecting. Point noted on running it out of the water.

[RightyO]

I noticed on the early posted pictures that you do not have the water outlet on the side of the boat ,all my 6 cylinder seacrafts had most of the water going out the side and only a small amount through the exhaust . I have a 63 model called Big Daddy in for repairs at the moment and it is running x2 headers but most of the water is out the side .I will try post some pictures of the set up . The original seacraft outlet set up had a block on the head held on with two bolts and one of the outlet ports went to the side and there was a tapered bolt that screwed in to one of the ports to restrict the water flow.
Ken

[WoodRay]

Thanks Ken but it does have the standard water outlet on the starboard side. I've even fitted a control valve so I can proportion the water going overboard to the water cooling the exhaust. Even with it set to unrestricted flow overboard I still get the problem.

[DaveD]

I took this photo of Woody's engine a few years ago if it helps.

[WoodRay]

Thanks Dave. I see that the injection points are well down compared to mine. I tracked down a boat site in the US and it does cover this problem with some pics. Seems steam expansion in the exhaust is a problem right down to damage to the exhaust valves. Hp loss is another issue due to cooling of the exhaust gases and the effect/change it has on sonic resonance in the exhaust. This in turn effects cylinder scavenging particularly with high overlap camshafts. I did however note that my injector tubes are just that at the exit points, tubes. Think I might crimp them down to get them to a spray pattern and possibly reduce the water flow. I'll also put them lower down in the manifold away from the port. I guess its a trade off against the risk of having too much heat coming off the manifolds and the resultant fire issue.
Pic is of an exhaust valve damaged from steam cracking.

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[WoodRay]

Well its been a while but finally got the replacement header manifolds fitted. Lowered the water injection points a couple of inches to see if that helps the problem. I more than likely wont do much more than that as I'll soon be making a start on the grey motor.
Glenmaggie is getting pretty low but still managed to get the boat in with our 2wd all but with a rope (Last Tuesday). Cant believe the weather but it looks to have turned today.

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[WoodRay]

Some long overdue work on the trailer this week. She's a bit too rusty to go on.

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[WoodRay]

In dry dock again this week. Frame done on trailer, hitch to go and prep for paint. Thinking it was dumb idea to start this late in the year with weather being so good this week. Glenmaggie beckons

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