Philip Duclos "Odds N Ends" hit and miss engine

[starnovice]

Brian,
This is a question and not a suggestion. I know from reading all of your builds that you have dealt with a lot of issues with the valves. Do you find the spring strength on the exhaust valve to be as critical as it is on the input?

Thanks
Pat

 

[canadianhorsepower]

Well actually Luc--I cut the seat at 45 degrees because thats the angle at which I made my manual valve seat cutter, and cut the valve at 46 degrees because I can manually adjust my lathe compound to whatever angle I want.

this could be your persisting problem If your valve angle is smaller then the seat44 to 45 it will sit at the top then you have to reduce your valve diameter to go and sit in the middle of the seat.The opposite is also true
th best thing is a 3 degree valve cut
one cutter 3 angle GOOD LUCK or 3 different cutter
here a picture that should explain it all
sure enought on a stationary engine it's not a must but it's sucess

 

[Brian Rupnow]

Luc---There really is no difference between a seat at 44 degrees and a valve at 45 and that of a seat at 45 degrees and a valve at 46 degrees. My effective engagement line on the valve is almost exactly in the middle of the 46 degree area, exactly where I want it to be.--Again I refer you to the posts 149 and 150 where you can see the engagement line on the valve. And good luck getting a 3 angle grind on a valve seat area that is at most .025" wide!!! Pat--The spring on the exhaust valve has very little criticallity compared to the intake valve. Since there is a mechanical rocker arm which lifts the exhaust valve, it is best to err on the side of "strong" as opposed to "weak" on the exhaust valve. The intake valve though, is a whole different story. It depends on atmospheric pressure (or if you prefer it "vaccuum") to open the intake so it has to be "weak"---but still strong enough to close the valve adequately when the piston is coming up on compression stroke.

 

[canadianhorsepower]

Luc---There really is no difference between a seat at 44 degrees and a valve at 45 and that of a seat at 45 degrees and a valve at 46 degrees. My effective engagement line on the valve is almost exactly in the middle of the 46 degree area, exactly where I want it to be.--Again I refer you to the posts 149 and 150 where you can see the engagement line on the valve

There is a difference other wise it would be the same angle. yes you did a great job centering it
all I can sugest you is try it with a pencil or suit ans notice the difference. Suit is so precise that's
what they are using as a thickness gauge for fire arm
cheers

 

[Brian Rupnow]

I have reached what my dictionary describes as an "im'passe"--"position, situation from which there is no escape; deadlock"!!! I have relapped the valves, starting with 350 grit, then 400 grit, then 600 grit, then toothpaste. I have compression.--In fact, on a free spin by hand, it bounces back from the compression stroke. HOWEVER-- this is when piston and valve bodies have a light coating of lubricating oil. When I try to start it, the Coleman fuel (which is tarted up naptha gas, so they can charge more for it) refuses to fire. Then, after not firing, it has the audacity to wash away all my lubricating oil, right down to the point where all sliding and sealing surfaces are metal to metal. Then of course, my compression drops off dramatically. I have a bright blue spark at the sparkplug, and it is firing at the correct time in the cycle. The exhaust valve is timed correctly, and I have rotated the engine by hand and carefully watched it go through all the four cycles, intake, compression, power, and exhaust. All of the appropriate things move at the appropriate time. Checked with a feeler gauge, there is clearance between the end of the exhaust valve stem and the rocker arm when the rocker is off the cam. I have wound a new spring from .015" music wire for the intake valve and have a fairly stiff spring on the exhaust valve to assure that it pulls the valve closed properly. I am running out of options at the moment, and that is what made me ask about propane for a fuel in another post. At least with propane, if the engine floods, its not going to wash away all of my lubricating oil. These are the times that try model engine builders souls, and I have went through this with every single one of the internal combustion engines I have built (and ran succesfully, this is my fourth engine.) I'm not sure where I'm going next with this, but I will keep you posted.---Brian

 

[starnovice]

... Pat--The spring on the exhaust valve has very little criticallity compared to the intake valve. Since there is a mechanical rocker arm which lifts the exhaust valve, it is best to err on the side of "strong" as opposed to "weak" on the exhaust valve. The intake valve though, is a whole different story. It depends on atmospheric pressure (or if you prefer it "vaccuum") to open the intake so it has to be "weak"---but still strong enough to close the valve adequately when the piston is coming up on compression stroke.

Thank you - Pat

 

[cfellows]

Brian, I know what you're going through. Makes you want to throw the whole mess up against a brick wall and go have a stiff drink!

One thing I do when I can't get an engine to fire is hook it up to an electric motor so I can keep it turning over while I mess with the fuel mixture. I start with the needle valve closed then start opening it a little bit at a time. A very slight turn of the needle valve can make a big difference. Even with poor compression I should think you could get something to go bang!

Chuck

 

[canadianhorsepower]

[quote Even with poor compression I should think you could get something to go bang!

][/quote]
if his flywheel are very heavy and compression a bit low..
could it be that it does not generate enought power to create a momentum???

 

[Brian Rupnow]

I'm turning it using my electric drill and a special quick disconnect adapter I made to turn the motor. The weight of the flywheels is not an issue. Its not firing at all. Not even a miserable little "pop".

 

[aonemarine]

Trick to starting old worn out low comppression engines, Warm the cylinder and bring it to temp before starting.
You might also want to consder a mix of methyl alchol and 2 stroke oil for first fire up.

 

[aonemarine]

You say you have spark, is this just testing at the plug wire or have you pulled the plug to make sure its jumping the gap?

 

[Brian Rupnow]

Trick to starting old worn out low comppression engines, Warm the cylinder and bring it to temp before starting.
You might also want to consder a mix of methyl alchol and 2 stroke oil for first fire up.

Thats interesting. How much 2 stroke oil to how much alcohol?

 

[Brian Rupnow]

You say you have spark, is this just testing at the plug wire or have you pulled the plug to make sure its jumping the gap?

Thats spark with the plug laying on the block.

 

[aonemarine]

40:1 mix warm the cylinder up too, helps fuel to vaporize. Once fired up and run for a bit you should be able to start cold, provided everything is seated in...

 

[Brian Rupnow]

Brian, I know what you're going through. Makes you want to throw the whole mess up against a brick wall and go have a stiff drink!

One thing I do when I can't get an engine to fire is hook it up to an electric motor so I can keep it turning over while I mess with the fuel mixture. I start with the needle valve closed then start opening it a little bit at a time. A very slight turn of the needle valve can make a big difference. Even with poor compression I should think you could get something to go bang!

Chuck

Chuck--How fast do you run it with the electric motor, and how do you connect the motor to the engine. The electric drill trick works great, but I run out of hands--One to hold the drill, one to tweak the carburetor, one to scratch my xxx. Most of my motors are 1725 RPM which is way, way to fast. Do you have a low rpm motor or run it through a gearbox? I have even thought about incorporating an over-running clutch bearing so that when the engine "catches" and takes off, it can run faster than whatever motor is driving it. My mind goes to a lot of funny places in the final stages of one of these engine builds.---Brian

 

[aonemarine]

Brian, did you try the change in fuel yet??

 

[Brian Rupnow]

Chuck---You were right. I donkeyied it up with a v-belt pulley in place of the one flywheel and a second v-pulley on my vari-speed drill, and an old v-belt. Motor took right off firing like a trooper after about 30 seconds of running with the drill. I don't have anything set up good enough to take a picture, but your advise helped a lot. Thank You!!!---Brian ----Still running same fuel.

 

[starnovice]

Congratulations!!

 

[aonemarine]

Congratulations, were looking forward to the video..

 

[metalmad]

Cool congrats
Pete