TOPIC: 1963 40hp Big Twin idling high/water pump?

I have a 1963 Evinrude 40hp Big Twin. I've never owned a boat before, but know about engines. It idles very high, and doesn't seem to be pumping water. Throttle cable is new, and adjusted correctly. Throttle blade opens and returns fine. Carb looked fine inside, but I replaced the needle and seat since I had it open. In this video the lean/rich screw is tuned all the way in (lean), and it seems to do nothing. The float is level. My carb rebuild instructions show a high speed needle in their diagram, but I just have a bolt in that location. Is that correct?

Also, is this the right seal kit? None of the seals look like they are the right size.

www.marineengine.com/newparts/part_search.php?part_num=18-2686

I'm seeing in other forums that the lower unit needs to be very deep in water for it to pump, does it look deep enough in the video? The water level is a few inches above the water intake port. Also someone mentioned that you need exhaust backpressure to tune the carb? Not exactly sure what that means, but does my engine need to be deeper in the water to tune the carb? Help! Please see the attached picture, and the links

Carb diagram: www.marineengine.com/parts/technical_information/sierra_18-7010.pdf

Video:

Early carbs had an adjustable hi speed jet, most bust have a brass screw & washer. That screw drains the fuel bowl & gives screwdriver access to the main jet.

Throttle plates must be all the way closed at idle. Throttle cam should not be touching the roller. Idle speed is adjusted by throttle lever stop screw on side of engine. Basically you are adjusting timing retard to control speed. If throttle plates are off the full closed position, the mixture screw will have little to no effect. Set mixture crew 1.5 turns out to begin with.

If that video is your motor, it looks like you need more water before the pump will pump. Fill the barrel full. And who knows if your pump is any good? Especially now that you have run it without enough water. Yes, you need back pressure before you can make a final idle speed or mixture adjustment. 2 stroke engines require back pressure of the water column of a muffler (ie, snowmobile or bike) so the incoming fresh fuel/air mixture doesn't just blow right out the exhaust port.

Thank you, I'm going to put it in a pond tomorrow and see how it does, and then try to make some adjustments

Okay, I dropped it in the pond and it does seem to be running much better. However, it is still not pumping water at all. The impeller is brand new, I made sure the keyway was lined up when I installed it, and the old one looked fine. I didn't see any passages clogged up. The shaft spins when I turn the prop. The lower unit was empty, I filled that with Type C. I shut it off when the temp gun was reading 198 degrees. Thermostat not working? I looked inside and it seemed okay. How do I remove the retainer thing for the plastic ball?

I'm kinda at a loss here for what to do. There's a 1969 Johnson 40hp on marketplace for $40. Should I grab that and swap something?

Were there 1 or 2 copper tubes running to the water pump to the powerhead? Early motors had 2 and when the t-stat was closed would recycle water back to the pump. If 2 tubes, perhaps you got the tubes reversed?
T-stat should open about 143 degrees.

Regardless if you have the 1 tube or 2 tube style, are you sure the tube(s) are properly in the water pump cover and didn't miss the target?

There are 2 tubes. You can't reverse the tubes, there's only one way to install them. And they are properly in the water pump cover.

So, I guess I should boil the thermostat in a pan and see if it opens? Can you explain how the check ball mechanism works? Not sure if I understand that system. Any other ideas?

Is it possible for the impeller to be in backwards? The new impeller was the same size as the old one. When I removed the old one some of the blades were facing the opposite direction. I've heard they are supposed to flip around while moving, but they clearly were not doing that.

So, I figured out my problem. I had a bad seal on my impeller housing, and I guess it was just sucking air and would not pump. Also, the housing may have been warped a little bit.

I figured this out by running the engine in the pond with the thermostat pulled, and a screw driver pushing the check ball down. All I was getting was hot air. I ended up buying that $40 Johnson and swapping the housing, seals and impeller over. I made about 10 laps around the pond, and the temp gun never said over 120 degrees. The seal is part number 10 in the diagram.

Chances are some impeller damage occured while the pump impeller was starved of water. Good that you got the spare engine.
You mentioned that you could close off the idle needle completely? Did that change once you added back pressure?
The thermostat, if working properly should allow a temperature of around 135f at the top of the cylinder head at an idle. That check ball allows water to by pass the thermostat once RPM climbs much past idle. The thermostat alone cannot supply anywhere near the water volume needed to cool the engine up on plane to WOT so the thermostat is basically by-passed. Engine should run on the thermostat at an idle. This promotes good idle quality and also keeps moisture out of the cylinders when operating in very cold water.