1976 35 hp evinrude leaf valves

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mrcrw009

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i just have a question about the leaf valves on my 1976 35 hp evinrude. the manual is very clear about the leaf valves needing to have a perfect seal and not to damage them. my question is that if the leaf valves do not seal perfectly would that make the engine run to lean of to rich?
 
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dcreek

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Re: 1976 35 hp evinrude leaf valves

I forget what the clearance is, so this is just a guess .015 or so. quick way is to look at the front of the reeds holding the back up to light, you shouldn't see much light, just remember your going to see a small amount to none. If you see a lot of light all the way around the reed, replace it. In my years I must say, reeds are seldom a real problem, when the piston is on its down stroke the pressure forces the reed closed. So short of being broken, I don't replace them. Oh never flip them over & use them, this can cause serious engine failure.
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

well there is a little bit of a gap but ya i was not thinking that it would make it run rich. the reason i ask is because the cylinders are getting flooded with gas and i have rebuilt the powerhead with new everything pretty much and i just rebuilt the carb. all i did to the carb was put new seals, float, float valve and seat but the engine is still running way to rich. i adjusted the low speed needle valve to were it will choke the engine out because its too lean then back it out to were it runs pretty good. no matter what the plugs get wet with fuel although i have not done a full power run on it yet so i have no idea what it will do at full throttle. i am running out of ideas. oh and it also has new points and one new coil the spark seems to be pretty good it jumps a 1/4 to 3/8 inch gap.
 
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dcreek

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Re: 1976 35 hp evinrude leaf valves

Set the high speed needle out 1/2 to 4/4 turn to start, low speed out 1 1/2 turns. Thats darn close to where you need to be, but adjudst from there for best performance. Float must sit level with the carb. body (top of the bowl when removed). Check your points for exact or close settings of .020 gap or if you haven't replaced this year do it now for next. poor point condition or setting will cause the problems you mention. Also time the carb. to ignition.
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

i could not get the high speed needle out to clean it when rebuilding the carb so i just left it.but that is where the low speed needle is, the float is level, and i replaced the points and gapped them along with the link and sink and feel pretty good about it. i can recheck all that but i have been there a couple of times.
 
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dcreek

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Re: 1976 35 hp evinrude leaf valves

Have you done a compression test? Did you use compressed air to clean out the carbs passages?To be honest theres other things that can cause this problem, but the list is long. When I say timing, did you time the carbs throttle roller to the center line of ignition armature?
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

ya did a compression test and was not to impressed but i think i need a new gauge. i got the cylinders bored out and put new oversized pistons and rings along with new upper and lower crankcase seals the compression was like 50 on both cylinders but i think it is wrong, it feels like it has a lot of compression
 
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boobie

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Re: 1976 35 hp evinrude leaf valves

I think you should try a different compression gauge first.
 
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F_R

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Re: 1976 35 hp evinrude leaf valves

mrcrw009 said:
i could not get the high speed needle out to clean it when rebuilding the carb so i just left it.but that is where the low speed needle is, the float is level, and i replaced the points and gapped them along with the link and sink and feel pretty good about it. i can recheck all that but i have been there a couple of times.
Click to expand...

Since a 1976 35hp does not have a high speed needle, I assume you mean you couldn't get the fixed jet orifice out. That orifice very well may be where your problem is. It is a precision part, and people goof it up by jamming wires and drills and such through it. Maybe you didn't, but the previous owner may have. If the hole is damaged or enlarged, it certainly will run rich. Anyway, that is where you need to focus your attention till proven wrong.
 
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dcreek

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Re: 1976 35 hp evinrude leaf valves

Don't worry yet about the compression. With new boring, pistons and rings it will take a few hours running time to seat them properly.
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

i like the idea about the fixed jet office and will try to get it out, although it was my dads boat and it sat for 15 years before i got it and it ran before it was parked. so i'm not sure if the office could really have changed at all but that is why i completely overhauled this engine cause it sat so long. I am also playing with the timing i have not ran it since but i advanced the timing just a little bit to try and burn the fuel better.
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

how is the unburned fuel return to the intake is it that line coming from right above the fuel pump, maybe something is going on there and i am also going to take a closer look at the fuel pump as well
 
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dcreek

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Re: 1976 35 hp evinrude leaf valves

If you go the removal of the high speed orifix route, be very careful not to damage it on removal. It made of brass, sometimes if they are stuck and you try to remove it you can damage to the point that it will not longer work and have to be removed. This is something you don't want to get involved in, take my word. Do as I suggested earlier, blow compressed air through the jet or orifix, though not the best route, it maybe the only without the costly repair or replacement of the throttle body. The compressed air might remove any blockage. Best to soak it 24 hours in a good carb. cleaner, remove and have at it while the insides are still wet.
It been a long while since I've look at the return lines, can't remember how their place, all I can say it check everyone twice, never rule out the simplest things.

Semper Paratus
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

ya i'm not going to try and remove the orfice cause it was not coming out. I did take apart the fuel pump and found where the incoming fuel goes through that little metal flapper check valve, where the valve seats the plastic is broken in two places so there is no way it would seal so it looks like fuel would be constantly coming in through the inlet. now whether that would make a huge difference i'm not sure. to me the outlet valve would still only open when the suction opened it but either way i'm going to replace it.
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

by the way thanks for all the advice everybody i do appreciate it!
 
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mrcrw009

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Re: 1976 35 hp evinrude leaf valves

by the way when i run the engine i have water coming out of the two cooling holes up top fine but also water squirts out of these two holes a lot while running is this right? it is those two holes right behind the steering collar

View attachment 119223
 
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