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Spitfire Question on anti run on valve 73 spitfire

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ScottFromNH

Senior Member
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Hey guys,

I have a question about the anti run on valve in the spitfires. I have a 1973 that I am redoing. Today while replacing the exhaust manifold I noticed I had to wires that were cut off half way down the firewall. After doing a lot of looking around I think I found where they use to attach to. I think someone cut the wires to the Anti Run on valve and trying to figure out why someone would do that? what does this valve do and should I be hooking the wires back up?

Scott
 
The valve only makes a difference right after you turn the key off. What it does is apply manifold vacuum to the carb float bowls, stopping the flow of fuel into the engine and hence ensuring that the engine cannot continue trying to run with the key off.

Not sure why it was disabled, since it doesn't affect how the car runs. Perhaps some other component was changed (like the carbs, ignition switch or oil pressure switch) so it no longer worked anyway. Or maybe someone just didn't like pollution controls :smile:
 
Hey Tr3driver,

thanks for the information. I guess I will have to wire it back up and see what it does. From what I can tell nothing has been changed on the car and after looking at photos I can tell the anti run on valve is suppose to be wired and it has nothing connected to it.
 
Oh great thanks for the link and yeah I am totally interested.. This is my first british rebuild and never did anything in this bad of shape so just trying to figure out what things are and how they work and why he disabled them or cut the wires.
 
If those wires do belong to the ARV circuit, the positive wire is "hot" when the ignition key is in the "OFF" position so be careful you don't strike a ground when you're fooling with it.
The ground wire for the ARV will originate at the oil pressure warning switch screwed into the engine block. Your saying that there are 2 wires at the firewall has me wondering if they are both truly part of the ARV circuit.
 
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