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Hi all,
Just took a look at my heat riser on my F1 226 and realized it is missing some parts. The picture below, shows the default position with the spring evidently missing. With the counter weight all the way down to the bottom left, is the riser operating in the cold engine position, or in the engine warm position? As I remember when I had the carburetor off of the manifold several months ago, I was looking directly through to the bottom of the manifold. At that time I did not see nor look for any type of door mechanism.
When I start the vehicle, if I lift the counter weight upward, I can feel a pulsing of the exhaust so I am thinking the door must still be inside the manifold. My concern at the moment is if I am running the motor with the door in the warming up position all of the time.
Another thing that may or may not be related is that when the engine is at full operating temperature, it develops a continuous mild miss or popping coming from the exhaust.
Thanks for any and all help.
Thanks for the picture Bill, I saw it on another thread that you had posted. Can you tell me if the spring and miscellaneous parts are on the outside of the manifold? If there is no spring like in my case, with the weight dropped all the way down to the bottom left side am I running with the door part # 9460 in the right position when the engine is at operating temperature? Or, do I need to wire the weight back up to the top? I don't really understand where the riser door position should be for cold engine starts versus full operating temperature.
Could just wire it open semi-permanently for now. The exhaust note will change audibly when moved back and forth. The weight will tend to hold it closed iirc.
Tedster9 That is what I would like to do. Wire it in the "open" position. I assume that is the position I need the door in for running at normal operating temperature? But could you tell me which way that would be? Does the position of the weight in the picture currently show it in the open position, or do I need to bring it up and to the right, about at 1 o'clock to be in the open position? And when you say open position, I am thinking you mean the door is horizontal inside the manifold? Gee I'm confused.
Thanks,
Tom L.
Take good care of that counterweight, really hard to find, near impossible. Probably around 10 or 11 o’clock is open. Once the spring gets hot it relaxes and the weight sinks to close the plate, probably 8 or 9 o’clock. There is a tab on the counterweight with an asbestos tip that rests against the manifold pin. If it’s open all the time your carb is going to boil over and evaporate all the fuel after shut down.
and for clarity, my open definition is that the plate is open to allow exhaust heat to warm the intake, closed is exhaust flow is blocked from the intake.
Thanks JB, that gives me a better idea of what is happening. However, I am thinking that close and open are terms that each of us look at in a different light. If so, I am leaning towards that if the weight is in the 8 o'clock position, we have an open exhaust flow that would be normal at full operating temperatures? If the counter weight is at the 10 to 11 o'clock position, we are operating with a closed door that inputs heat to the carburetor? Does that sound logical, or am I still not seeing what is going on?
Also, if you were to remove the gate, or flapper from the heat riser all together, what kind of operation would one expect?
I edited my post. I wouldn’t remove the flapper. Fuel would boil over probably. I have an old thread where I rebuilt the heat riser. My counterweight kept falling off so I safety wired it on, but I think my safety wire was impeding the valve. I wired it closed and now just give it a minute for the intake to warm to increase atomization before I put it in gear.
Thanks JB.
Now it all comes together. That is what I needed to know.
I will research the heat riser files once again and find your original post. I am thinking I might have come across it already.
Now that you have set me straight on my original questions, I am wondering after taking another look at the heat riser, how much the bushing on the riser shaft that allows an exhaust leak, affects the smoothness of engine operation?
Should I be concerned? Would it be a good idea to plug the area of the shaft that is leaking and wire the riser in place?
Thanks for the picture Bill, I saw it on another thread that you had posted. Can you tell me if the spring and miscellaneous parts are on the outside of the manifold? If there is no spring like in my case, with the weight dropped all the way down to the bottom left side am I running with the door part # 9460 in the right position when the engine is at operating temperature? Or, do I need to wire the weight back up to the top? I don't really understand where the riser door position should be for cold engine starts versus full operating temperature.
9467 spring is on the outside, it's the same 1948/56 F1/F6 .. F100/600 all I-6's = B4A-9467-A
Thanks Bill for the part number on the spring.
The more I look at the first parts pic you posted, the more I think I must be missing part of the assembly.
If it ever warms up enough to go back out in the garage to work, I will take a closer look today and determine if it is worth fixing.
Thanks again,
Tom L.
1949 F1
Just to clarify... 'Open' means the flap is in position to allow exhaust to flow unimpeded to the muffler. 'Closed' means the flap covers the path to the muffler. The spring closes the flap and when hot it allows the weight to open it. Without a spring, and if the shaft moves freely, the flap should default to the open position. Also, when cold and the flap is closed by the spring, exhaust flow pressure from the engine will overcome the spring tension and allow flow to the muffler.
I'm not familiar with your engine but for mine the spring is no longer available. I found one for a Jeep, on ebay, that was wrapped in the correct direction. Around $15, but still cheaper than anywhere else I could find. My engine is currently at the machine shop so sometime soon I should have the spring installed - after I get the shaft unstuck. ;-)
Thanks Beav for the info. That is how I look at it.
After taking another look at the heat riser, it looks like I am missing not only the spring, but part numbers 9463 and 9449.
I am guessing, that these parts may be hard to come by?
Tom L.
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