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post #1 of (permalink) Old 02-25-2002, 06:56 PM Thread Starter
 
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Intake/Exhaust Passage valve?

On my 77 258, there is a passage valve below the carburetor that opens between the exhaust and exhaust pipe. This "flap" valve used to be controlled by a thermal spring.... rust has won the battle with the spring.

My questions are...
will this affect my engine performance?

The spring is no longer availabe so what do I do?

Should I put the valve in the closed position and lock it there?

What did I gain with the valve in operational condition?

thanks

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post #2 of (permalink) Old 02-25-2002, 08:01 PM
 
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Re: Intake/Exhaust Passage valve?

Passage valve? How bout an EGR valve? If that's what it is, then yes it can hamper performance. Since I have no emissions, I couldn't tell you how it's normally setup.

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post #3 of (permalink) Old 02-25-2002, 09:37 PM Thread Starter
 
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Re: Intake/Exhaust Passage valve?

It is not the EGR, I think I may have found the answer.

it's called an exhaust heat valve, it stays closed (blocking exhaust gasses from exiting) untill the manifold warms up then the thermal spring opens the valve, letting the exhaust gasses escape.

so it seems that I should just lock the valve in the OPEN position.

thanks

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post #4 of (permalink) Old 02-25-2002, 09:37 PM Thread Starter
 
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Re: Intake/Exhaust Passage valve?

It is not the EGR, I think I may have found the answer.

it's called an exhaust heat valve, it stays closed (blocking exhaust gasses from exiting) untill the manifold warms up then the thermal spring opens the valve, letting the exhaust gasses escape.

so it seems that I should just lock the valve in the OPEN position.

thanks

I've got too much month at the end of my money!
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post #5 of (permalink) Old 02-25-2002, 11:20 PM
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Re: Intake/Exhaust Passage valve?

Isn't that called a choke stove or something? And, would it not be better to have it shut all the time?, If it is always open, won't that let un-neccesary heat soak your carb+manifold? Just wondering [img]/wwwthreads_images/icons/tongue.gif[/img]

post #6 of (permalink) Old 02-26-2002, 02:19 AM
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Re: Intake/Exhaust Passage valve?

You got it. It's a "pre heater" for the carb. My spring is missing also, and I run mine opne to freeflo exhaust all the time. Do you have any ideas how you are going to keep it open? I haven't found anything that works real well for me yet. Also which way are you turning yours to open the exhaust. It's been a while since I did mine (dissasembled and easy to tell) and I need to do it again.
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post #7 of (permalink) Old 02-26-2002, 07:36 AM
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Re: Intake/Exhaust Passage valve?

There used to be a counterbalance weight on those. The weight pulled it open, and the spring closed it. As the spring heats it relaxes and lets the valve open. If you just remove the spring, the weight should pull the valve to the open position and keep it there.

The purpose of the valve is to warm the carb and intake manifold to help vaporize the fuel in a cold engine. Removing it will cause more stumbling and spitting for a longer time after startup.

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post #8 of (permalink) Old 02-26-2002, 08:07 AM Thread Starter
 
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Re: Intake/Exhaust Passage valve?

Thanks for the info.

as for the cold starts, it dosen't get cold down here in GA.

I guess for now I amgoing to leave it open

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