Rookie red plate jetting

What is it about the restricted engines that makes them want to run so rich? Has anybody ever put a EGT on one?
Al it isn't that they "want" to run rich, you have to make the fuel circuit very rich in order to pull enough fuel through the plate because the plate kills the fuel signal.
 
Al it isn't that they "want" to run rich, you have to make the fuel circuit very rich in order to pull enough fuel through the plate because the plate kills the fuel signal.
When I said "them" I was referring to the engine. Apparently, they, meaning the engine, need to be rich to produce the power. This goes against all my understanding of the internal combustion engine.
 
When I said "them" I was referring to the engine. Apparently, they, meaning the engine, need to be rich to produce the power. This goes against all my understanding of the internal combustion engine.
My understanding of it is they do not make enough vacuum to pull enough fuel into head. I could have definitely just looked like a idiot but I'm sure a expert will chime in.
 
My understanding of it is they do not make enough vacuum to pull enough fuel into head. I could have definitely just looked like a idiot but I'm sure a expert will chime in.
That is correct, the plate makes everything change, the smaller the plate the worse the effect...
 
This has nothing to do with rich/lean. This has to do with the fact that the restrictor plate, by design, provides a weak signal to the carb, or in other words reducing the Bernoulli effect through the venturi.

It is caused by not only the size of the hole in the restrictor plate but also it's location. Folks savvy enough to notice, will note that the hole that serves as our restrictor is not centered in the carb's venturi. The purpose is to provide an improved signal to the pilot circuit, as the expense of hurting signal to the emulsion tube and main jet that sits below it.

Therefore, since the signal to the carb is poor, or should we say poorer that an unrestricted engine, larger jet sizes (than what would be used in an unrestrcited engine) are used to compensate. The take-away here is: the overall amount of fuel supplied to the engine is neither rich nor lean.

Food for thought, one of my red plate engines piloted by Mason Harper took 2nd place out of 22 of the best teams in the country at the Maxxis Nationals "Thunder in the Valley" in Neeses, SC on Oct 12th, 2019. I am super proud of that.
 
My understanding of it is they do not make enough vacuum to pull enough fuel into head. I could have definitely just looked like a idiot but I'm sure a expert will chime in.
I don't want this to sound like an insult, it's not, but keep it in mind that; nothing gets pulled, it all gets pushed. The pressure differential between the inside of the carb and the atmospheric pressure outside is what is doing the pushing.
 
Dang I've been setting here thinking that the intake stroke takes place when piston starts the downward travel, not when was on the upward travel pushing air! Im sure I'll be wrong again
 
unless he's talking about (dont know correct terminology) but where the intake vavle does open the last few degrees of the exhaust stroke who knows I'm still learning no expert here
 
unless he's talking about (dont know correct terminology) but where the intake vavle does open the last few degrees of the exhaust stroke who knows I'm still learning no expert here
That would be overlap.... ;) nothing to do with what Al is thinking. I think he is trying to explain the venturi effect inside a carb and what makes the E tube and main jet work as it does. But it is a fact that 4 cycle engines DO produce a vacuum that PULLS air and fuel into the Combustion chamber.
 
Explained to me the mechanism by which a vacuum pulls. Name the force. Antidotal remarks aside, there is none. The air pressure at sea level is about 15 psi. If your body didn't have the same equalizing pressure inside it, what do you think would happen to the human body. Pump the air out of a 5 gallon can and see what happens, it collapses. Do you think the vacuum inside collapsed it, pulled it in? Or is it possible the air pressure differential collapsed it. Low-pressure inside, atmospheric pressure outside, what happens?
It's like this; you've had this hard and fast knowledge for your whole life, now some idiots trying to tell you it doesn't work that way! I understand!
Think about it like this; one square foot, 144 in.² x 15 psi equals 2160 pounds force. That's a lot of pressure. How many square feet of surface is there on the human body. Multiply that by 2160 and that tells you how much force there is pressing against the human body. If there wasn't an internal equalizing force, you can only imagine what would happen. When you put your hand over that carburetor, you can then imagine what is happening.
 
Al,. You can give us back yard mechanics all the lingo jingle you want to but you are not going to convince us that when we feel a suction on our hand when we place it over the carb when the engine is running that the feeling we get is a push and not a pull.
 
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