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Britishbest

Anti Run on (ARO) Valve

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Hey Guys,

 

I had another thread which covered starting issues and running on. As this is specifically about ARO's I've done a new thread.

 

I have been advised by a TR specialist to fit an ARO onto the inlet manifold as we have gone though everything else on the engine and ignition system but running on continues. This would introduce air into the CC when the key is switched off.

 

My quetion is do they work? Has anyone used them? Any problems?

 

I've done a bit of research and I believe they were fitted to a lot of 80's BL cars. Google shows the MG crowd using them.

 

Would be grateful for any advice. I'm not keen to stall the car every time I shut it off.

 

Thanks

 

Colt

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Hi Colt,

 

Nice to chat again, some cars are prevalent to the running on than others, the anti dieseling valve works fine normally and as far as I know there are no side effects.

 

Mick Richards

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Colt

My 1973 American spec TR6 has an anti run on valve fitted from new which is very effective, when the valve went wrong a while ago the car would run on especially if I was using cheap petrol.

Triumph were quite cleaver as the valve not only introduces air into the manifold it also creates a vacuum in the float chambers thereby pulling the fuel away from the jets. If you have the Brown book its shown in the section on Emission Control.

 

George

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I fitted one in 1998 - it reduced the tendency to run-on, but, with the engine ticking over, I always engage 1st gear and raise the clutch pedal to the point where it starts to reduce engine speed, then turn ignition off.

Ian Cornish

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Have you tried a higher octane fuel? My 4A will run on if I use 95 octane but fine on 97+.

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We had a 4a in a while ago that would constantly run on despite an Anti run on valve being fitted to it, Proper re time and tune along with valve clearance reset and some re routing of fuel pipes stopped all that.

Stuart.

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Hi Colt,

 

I did as a DIY-project what most producers did on their carburetors to avoid this problem:

I fitted a electric petrol valve to swich off the pertol that goes to the ideling jet.

 

My 1974 Volkswagen Polo alreday did that and I know the Beetle always did it that way.

 

That's a little tricky on SUs because they have no ideling jet,

but for example Mercedes Benz did that on their cars in the 80 when using Strombergs.

 

Works on my HS6 very well, I always keep the ignition on and switch off the pertol by a push switch under the dashboard.

Engine always stops relaiable and immediatelly without running on. But the valves must be in the hose from the float chamber to the jet!

 

To stop the engine by a air valve for me is a little bit of "negativ x more negativ = positiv" logic.

 

Ciao Marco

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Thanks for the replies guys.

 

Protek have just retuned the car and its running well again aside from the running on. Estimate on BHP is around 135 with the usual hi lift cam, 89mm bores, ported head, tubular manifold, higher compression etc. etc. so this doesn't help run on.

 

I have tried the higher grade fuel and additive. Cooling is via Revotec fan that cuts in pretty early, coolant is 50% mix, cant recall make, Carplan possibly?.

 

The car was fine until early summer and then it started.

 

I will reset the tappets again as this wasn't done and its been a few months.

 

Is the ARO valve Moss does the one to go for?

 

Thanks

 

Colt.

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Hi Colt,

 

I did as a DIY-project what most producers did on their carburetors to avoid this problem:

I fitted a electric petrol valve to swich off the pertol that goes to the ideling jet.

 

My 1974 Volkswagen Polo alreday did that and I know the Beetle always did it that way.

 

That's a little tricky on SUs because they have no ideling jet,

but for example Mercedes Benz did that on their cars in the 80 when using Strombergs.

 

Works on my HS6 very well, I always keep the ignition on and switch off the pertol by a push switch under the dashboard.

Engine always stops relaiable and immediatelly without running on. But the valves must be in the hose from the float chamber to the jet!

 

To stop the engine by a air valve for me is a little bit of "negativ x more negativ = positiv" logic.

 

Ciao Marco

Interesting Marco. What valves have you used in your HS6 jet tubes?

 

I have experimented with aro valves. The Moss one is very much like a Ford Escort aro iirc. They are energised all the time you are running and get very hot. I have had one fail. There is an arrangement that uses a normally closed valve and a link to the oil pressure switch but I have not tried that. I am presently using one from China (eBay) which has a larger bore than the Ford one. It runs on less but still does it occasionally. I have also tried cooler plugs but no joy so I use Denso Iridiums now. My cylinder head is skimmed and Peter Burgess modified so higher CR.

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In the late 70s I worked for a company that made ARO solenoids for Ford to prevent the Fiesta 948 engine running-on. Around the time of the OPEC oil crisis we were asked to look at 'reversing' the solenoid to push rather than pull, so it was not always energised. This was intended for use with a system to blank the slow-running jet if the throttle was closed AND the engine rpm was >1000, to save fuel when coasting.

I developed an electronic module to perform the control function, found the company had a "spare" Mk II Escort, fitted the system and did fuel consumption tests with the system switchable, so I could do a run, switch the system off, refill the tank and perform the same run. It seemed to save between 3 and 6% of fuel consumption.

Ford were impressed, but had decided not to go ahead; reasons included that the oil crisis was short-term, increased complexity would be unpopular with owners and service agents, and of course PI would make electronic control of carburettors obsolete. It did lead to me being offered a job at Ford though!

 

Pete

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If cooler plugs dont kill runnin-on, the next hotter source of autoigntion are the exhaust vlaves. A good reason not to have the seats 'gas-flowed'- heat transfer is slowed. Also hot cams - the extra degrees when ev is lifted will also make the evs run hotter. Accumulated crud on the evs also.

Peter

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Hi Pete,

 

I used the Pierburg valves Mercedes Benz used with Strombergs on their M102 engine,

fried of mine, TR-Tom reported on his blog https://trtom.wordpress.com/2016/12/24/anti-run-valve-for-su-hs6-carburetors/

 

You get them occasionaly used or NOS on Ebay, and you need some skills to make the valve body and a lathe.

It was my winter project 2015/2016 and with the result I am VERY pleased.

 

By the way one thought:

 

what keeps a engine running, fuel or ignition? Both!

Why not switch off the pertol when switching off the ignition does not work?

All Diesel engines stop that way.

 

Ciao Marco

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Thanks Marco. That’s beyond my skills, nice job. If you decide to offer it as a kit I’m first in the queue.

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Thanks Marco. Thats beyond my skills, nice job. If you decide to offer it as a kit Im first in the queue.

Hi Pete, thanks, I take you on a list as # 1,

challenge is to get two of the Pierburg valves and their price, each about 50 - 100 Euro

 

 

.

Edited by Z320

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You say you have a revotec fan and the problem only started in early summer. Have you got the fan wired through a relay with a seperate circuit so it cant generate power to the coil on shut down? this will create run on.

 

Graham

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You say you have a revotec fan and the problem only started in early summer. Have you got the fan wired through a relay with a seperate circuit so it cant generate power to the coil on shut down? this will create run on.

 

Graham

This is worth checking as the Revotec was newly fitted, .

 

Thanks to everyone for their replies, if the fan isn't the culprit I will go with the ARO valve.

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