Pressurized vs Vented

mrtwist02

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Hello, I've got a quick question. I have a 1960 40 horse RDSL-22. Would I need a pressurized tank or a vented tank for this motor. How much of a difference(if any) would that make on running this engine. Sorry Newbie here.
 

jimmbo

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Re: Pressurized vs Vented

Vented is what your engine uses.
 

tashasdaddy

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Re: Pressurized vs Vented

vented single line thank. the new plastic tanks will be fine.
 

F_R

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Re: Pressurized vs Vented

Hello, I've got a quick question. I have a 1960 40 horse RDSL-22. Would I need a pressurized tank or a vented tank for this motor. How much of a difference(if any) would that make on running this engine. Sorry Newbie here.

How much difference? A lot. It won't work with a pressure tank.
 

mrtwist02

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Re: Pressurized vs Vented

Thanks guys, I have it connected to a vented tank, looks like I'm gonna have to rebuild the carb. Does anyone have the schematics to rebuild this carb, I'm better with visuals. My manual has more words than anything. Is this going to be a tough job. It usually works better if I'm more prepared and where would i find a carb kit for something this old? Thanks again!
 

F_R

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Re: Pressurized vs Vented

Do you have a reason for rebuilding the carburetor? Or are you just assuming it would be a nice thing to do?
 

Joe Reeves

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Re: Pressurized vs Vented

I assume that the engine is electric start? (Different Carbs)
 

mrtwist02

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Re: Pressurized vs Vented

Yeah it is electric start. Automatic choke. The reason I want to rebuild it is after i fixed the clutchdog problem, i took it out to run and it starts just fine idles fine but when i I give it WOT it doesn't plane out. I thought it might of been the gas tank. I'm running 24:1 which the manual states. But it just seems doggish does this have a fuel filter of some sort. maybe it's clogged. The carb looks like it has newer gaskets which leads me to believe it has been recently rebuilt, and if it has, i don't know if doing it again will help. I have tried messing with the high speed and it doesn't seem to give me more power. I even tried to put the choke on while at WOT and has no affect. I'm just stuck.
 

F_R

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Re: Pressurized vs Vented

Does turning the high speed needle affect it at all?

Too rich and it should run rough....we call that "four cycling"..seems like it is firing on every other stroke. Sort of like chugs along.

As you approach the too-lean condition, it should smooth out and maybe pick up speed a bit. But when you go past a certain point it should rapidly lose power and probably quit.

Proper adjustment is when you approach too-lean and then back it off toward rich till it regains power.

If you can acheive both of those extremes the carburetor is doing all it is supposed to do. If the adjustment linkage is improperly installed you may not be able to turn it far enough to acheive both extremes.
 

mrtwist02

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Re: Pressurized vs Vented

Yeah Ive tried adjusting both the low and high speed. I believe i have them both set to the point of sputtering and back em 1/4 turn like the manual says. Even after all that it just seems like its lacking power. Is the fuel filter plugged or something. It just seems like i should be getting more RPM's I did take a look at the throttle linkage and everything seems fine. What else am i missing ?
 

F_R

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Re: Pressurized vs Vented

Well, either you are expecting too much, or your motor is running on one cylinder, or your motor is sick. You need to do basic troubleshooting. Compression, ignition. Just how much do you figure it is lacking? 1/2 speed or less??
 

mrtwist02

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Re: Pressurized vs Vented

Well looks like I now have a weekend project. Gee just when I thought I didn't have enough :) The boat this is attached to is a pretty light, it should plane out tho right? My grandfather has a 12' Jon boat with a 73 4.5hp Sea Horse and i can get that boat to plane out. So i figure a 40hp should plane out a 15'.
 

Joe Reeves

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Re: Pressurized vs Vented

That engine is designed to operate on the 50/1 fuel/oil mixture.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

60_40hp-E_CARB-1a.jpg
 

samo_ott

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Re: Pressurized vs Vented

I have to agree with Freddy, the original ratio was 24:1. You're free to mix it as you choose but I always use 24:1 on my pre '64 engines (as specified by OMC). It's also a long running (never ending) debate on this forum.

Also, I would check the compression on the engine. It's the first thing I always do on a new engine for a baseline. And as already mentioned, you might be running on 1 cylinder. Check to see if you have a strong spark on both cylinders.
 

Joe Reeves

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Re: Pressurized vs Vented

The powerhead of that engine is designed, using "all" needle, roller, or ball bearings on all of its moving parts, therefore it is designed to use the 50/1 fuel/oil mix. I can recall working on those engines when they were brand new and am well aware of the original 24/1 mixture.

Bottom line...... It is designed to operate perfectly on the 50/1 mixture. I wouldn't state that if it were not true.

Notice that at no time did I say that it "was" designed, but rather that it "is" designed, a term designated to signify acceptance of a later innovation.

Perhaps this is what ex-president Bill Clinton referred to when he questioned the definition of "is" (grin). Now he might be enlightened.

There are many engines of that era that have needle, roller, and ball bearings incorporated in their design EXCEPTING perhaps the center main bearing OR the wrist pin bearing. In these cases, the original mixture should be adhered to.
 

Sea18Horse

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Re: Pressurized vs Vented

I recently got a '58 18 horse parts motor. And when I tore it all apart I was surprised to find it had needle bearings in all positions. Including the wrist pins and the center main bearing. I since discovered that my '57 18 is identical. So I plan to switch it over to 50/1. My '56 10 horse has bushings in the center main bearing and rod and wrist pin locations. So I'll keep it on 24/1.

So mrtwist02, is your boat a 15' fiberglass? Any chance your hauling around 500lbs of waterlogged flotation foam? If it's older there's a good chance. A lot of people are caught out by that. The boat should be light but it turns out it's not.

Cheers...................Todd
 

F_R

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Re: Pressurized vs Vented

mrtwist, of course a 40 should plane a 15 ft boat, unless there is something seriously wrong with the boat. Check that motor for compression and running on one cylinder.
 

mrtwist02

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Re: Pressurized vs Vented

Hey Guys, Been a few days. Let me tell you all about it. I took the carb off rebuilt it with all new parts, checked all the linkage everything works like it should. I checked compression and rings everything is fine. But when everything went back together, same problem, Now I have taken the carb apart several times and put back on, same problem, Then by chance I happened to notice the the butterfly on the carb was only opening halfway, Closer inspection revels that the linkage was slightly bent and hitting the bracket for the Generator. Needle nose pliers and a little twist, Full WOT and she flies across the water.Planes out very nice. Don't I feel like the horses behind LOL........Randy
 
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