Motor Run On

[wooolffy]

I have a 76 TR and a question on run-on. When hot ot will run on, I have checked the anti run on solenoid and it is not hooked up. A new wiring harness is installed along with new ignition switch from PO. Checked solenoid and it works, wiring to oil pressure switch is okay, but the ignition switch has no wire for anti run on solenoid. Do we need solenoid or have some of you found other alternatives. Any help would be of great value.

 

[tr6lover]

hi woolffy, first thing to do is check the timing, a bit advanced and it can cause run on. is this the stock engine in stock tune or does it have higher compression etc? run on is caused by a hot spot in the cylinder head, this could be a piece of carbon or a sharp edge which ignites the fuel. the run on valve releases the vacume to the intake so no extra fuel can be sucked in once the ignition is shut off. if the timing adjustment doesnt fix it the easiest fix would be to make the run on valves work. if one doesnt do it you could also add a second one.
Randy

 

[Tinster]

First check your timing and then try a tank of
premium fuel- higher octane, less run on.

d

 

[TR6oldtimer]

Use higher octane gase, fix the anit-run on valve, then tune for performance.

 

[Tinster]

Hey Ray,

Just wondering here. How you tune the Crypt Car for
performance? Cyrpty's performance to date has been rather
lacking.

dd /bcforum/images/%%GRAEMLIN_URL%%/wall.gif

 

[Billm]

I know nothing about Triumph run-on valves but I know that VW and Toyota run-on's only allow fuel to flow through if they have power to them, when the ignition is shut-off then they close which is what your's should be doing (assuming that it is a similar system). My guess under that senierio is that your valve has been "gutted" to prevent shut-off and that replacing it with a good one and hooking it up to an ignition "hot" wire should help.
Bill

 

[Brosky]

Here's the proper way to wire the switch for the TR6 anti-run on valve.

And here's a bigger story about them: https://www.britishcarforum.com/bcforum/ubbthreads.php/ubb/showflat/Number/259696/page/1/nt/2/fpart/1

 

[wooolffy]

I noticed in my Moss catalogue that a four pole ignition sw is usually the norm, but if you have an anti run on valve then a five pole sw is used. My question is where is the wire to hook up to ignition? Or did the new wiring harness only come with four wires. The harness has only four wires going to igniton sw. Guess I'll try the timing, using high test petrol on a basically stock motor.

 

[AltaKnight]

I noticed in my Moss catalogue that a four pole ignition sw is usually the norm, but if you have an anti run on valve then a five pole sw is used. My question is where is the wire to hook up to ignition? Or did the new wiring harness only come with four wires. The harness has only four wires going to igniton sw. Guess I'll try the timing, using high test petrol on a basically stock motor.

Then do as a lot of us do and simply stall it out while at a standstill in high gear, simply release the clutch at idle.

 

[guzzul]

I noticed in my Moss catalogue that a four pole ignition sw is usually the norm, but if you have an anti run on valve then a five pole sw is used. My question is where is the wire to hook up to ignition? Or did the new wiring harness only come with four wires. The harness has only four wires going to igniton sw.

The '76 TR ignition switch should have 6 connection points. The Moss catalog indicates you should order 667-875, which is a 6-wire switch. The switch comes with a wire toggle that has a 5-pin connector, plus a separate wire for the AR valve. VB sells this as their part number 0-806.

As per Brosky's earlier post, the AR valve needs power from the ignition switch when the ignition is OFF, not when it is on. You can't just tap off any ignition power source. Also, make sure you check the oil pressure switch for proper operation, otherwise when you get it hooked up you could wind up with the same problem Paul had (battery drain).

To the other advice here about timing and higher-octane gas, I would add make sure your curb-idle speed is close to spec. High idle will encourage run-on.

The AR valve does a pretty good job when it's working right.

 

[TR3driver]

Then do as a lot of us do and simply stall it out while at a standstill in high gear, simply release the clutch at idle.

I'll second that, although it doesn't even need to be in high gear. Just apply the brakes firmly, leave it in whatever gear it was in when you stopped, and let the clutch out just after you turn the switch off. I make it a habit, just part of the motions I use to shut off the car (along with touching the light switch to be sure it's off and dropping the keys in my pocket).

All of my Triumphs have run-on at least occasionally; a side-effect I believe of the witch's brew they sell for gasoline around here. The vacuum retard (and correspondingly higher throttle opening at idle) makes the problem even worse (which is why Triumph added the ARS only to later cars with the retard).

 

[Brosky]

I disagree with allowing the run on to continue. Whether we agree with some of the emission crap that was installed, the anti-run on valve was a simple device, compared to most other additions of the 70's. It will lean the mixture and prevent the run on condition as the car is shut down.

Now, why do I say that I disagree, aside from what I just said? After all of my years in the business, I can assure you that an engine that continues to run after the ignition is shut off, is an engine losing life and it may happen quicker than you think.

Years ago, run on was mainly caused by timing that could be advanced too far and also created detonation or "ping" as it was commonly referred to at the time, upon acceleration if the octane in the fuel wasn't high enough. Carbon deposits began to be built up from the unburned fuel collected on the top of the piston from forced shutdowns and premature detonation. After a while, this carbon would get hot and start to smolder, but would never quite burn away, so the hot spot on the carbon would ignite the fuel prematurely and add to the detonation or early firing of the fuel/air mixture creating ping. The situation would continue until a piston either cracked or had a hole burned into it.

At the same time, carbon deposits also would start to grow on the valves and they would also become targets for premature wear and burning.

Given the right conditions of a slightly rich fuel mixture and the proper amount of carbon, an engine will continue to cough and sputter away and a forced shutdown will put a great deal of unnecessary force on the pistons, rods, crank and bearings. The weakest link soon becomes the piston, since it is subjected to the constant explosion of normal combustion in a four cycle engine. Anything that upsets the balance or routine of the precisely controlled intake - compression - combustion - exhaust cycle, by adding premature detonation in one cylinder while another is firing, also adds a great deal of stress to the engines internal components.

If run on was good, all racing engines would allow it. I have seen MANY cracked pistons, scored cylinders, broken crankshafts and other related issues caused by run on and improperly timed detonation.

Sorry for the long winded explanation, but if it were my car, I would take whatever steps were necessary to correct the problem, because I can assure you, no car was designed to run on after the key is turned off. Correcting the problem is usually more simple than one would think.

 

[wooolffy]

My anti run on valve works with battery hook up, what should /could I use to power it the same as it would off the igintion switch? Refering to turning off power whe oil pressure switch drops out?

 

[wooolffy]

I have traced brown wire with red stripe all the way back to wiring harness exit at ignition sw connection.So if I were to run a wire from here to a hot line when ignition is off this anti run on valve should work? Yes?

 

[TR3driver]

I can assure you that an engine that continues to run after the ignition is shut off, is an engine losing life

But it's the actual running-on that hurts it, not the conditions that lead to run-on. Killing it with the clutch before the carbon can ignite leftover mixture won't hurt anything at all.

I've done well over 100,000 miles with an engine that wants to run-on sometimes (usually when underhood temperatures are high), and it's not suffered any ill effects that I see from it.

So if I were to run a wire from here to a hot line when ignition is off this anti run on valve should work? Yes?

Problem is, it has to not have power when the ignition is on. Otherwise you'll have a very hard time getting it started (basically have to crank until the oil pressure comes up and disables the ARS unless it happens to fire first time).

One solution is to wire a relay to the ignition circuit (white wire), and use the NC contact to supply power to the ARS. Any auto parts store should have a suitable relay, or here's one on flea-bay
https://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170120232255

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I've done well over 100,000 miles with an engine that wants to run-on sometimes (usually when underhood temperatures are high), and it's not suffered any ill effects that I see from it. [/QUOTE]

Randall,

The key word in your reply is "sometimes". Under those circumstances and if they were, rare, I would tend to agree with you. But if it is at all possible to eliminate the condition, that would be a far better alternative to allowing it to continue, from what I've seen in the past.

JMHO and nothing more.

 

[guzzul]

I have traced brown wire with red stripe all the way back to wiring harness exit at ignition sw connection.So if I were to run a wire from here to a hot line when ignition is off this anti run on valve should work? Yes?

If you have a 4-connector ignition switch then your Brown/Red wire is probably not hooked up to the ignition switch, correct? So at this point you do not get power on it when the ignition is either on or off?

I would be very careful about tapping into wires that are 'hot' when the ignition is off. And I can't think of any other circuit that operates hot when ignition is off, but cold when the ignition is on - and that's the combination you need.

My anti run on valve works with battery hook up, what should /could I use to power it the same as it would off the igintion switch? Refering to turning off power whe oil pressure switch drops out?

Why not install the right 6-connector switch? It occured to me on your first post that maybe the PO installed a 4-wire switch by mistake or maybe it was just a matter of convenience. The 4-connector switchs are pre-73 I think. It sounds like your Brown/Red wire is there in the harness and connected to the ARS, but just not connected at the ignition switch. If you still have a '76 wiring harness, then you should be able to use the later switch.

The Brown/Red wire should run from the AR solenoid to your ignition switch, connection 6. The other side of the AR solenoid should have a White/Purple wire that goes to your Oil Pressure switch, configured as in Brosky's previous post.

When the ARS is on, it bleeds partial vacuum into the carb float bowl via the charcoal cannister. The partial vacuum is enough to stop fuel flowing up into the jet from the bowl. Its a simple system and it works well, but if you connect it up wrong or if the component pieces are not working properly you can have all sorts of strange problems. Your charcoal cannister needs to be hooked up properly too.

The way its meant to work is:
Ignition off (+12V) and Oil Pressure HIGH (Ground) = ARS on, fuel flow stopped.
Ignition off (+12V) and Oil Pressure LOW (No Ground) = ARS switches off, fuel flow normal again.
Ignition on (No Power) = ARS off, regardless of Oil Pressure Ground, and fuel flow is normal.

 

[Tomster]

the run on in the 4A seems to have been cured by using premium fuel ($1.23 per litre vs $1.10 per litre) Now I am wondering if anyone has found a proven Octane booster that really just boosts the octane?
Thanks to the earlier suggestions to try this!

 

[toysrrus]

Hi There Tomster;

Well; I just wanted to suggest simply changing to Premium Gas: At $3.00 gal. it does`nt matter what brand but I use Sunoco:

When I first got my TR4; I was running strictly 93 octane: Then as the Gas Prices got crazy; I would occassionaly switch to 89 Octane: "Instant Run-On":

Switch back to 93 & Problem solved:

Try it for the heck of It if you wish: Go back to the Lower Octane and see what happens: I`d bet "Run-On":

See Ya All later;

Regards, Russ /bcforum/images/%%GRAEMLIN_URL%%/banana.gif

 

[vettedog72]

Common sense should tell you that repeated events of “bog down shut off” results in premature bearing wear. Oil pressure is at its lowest and the rod bearings, main bearings and piston pins are getting additional stress from engine run on. Clutch wear? Yea, that too.

The conditions that cause the run on have to be a drain on performance. One point is the hot spots causing the ignition will rarely be even cylinder-to-cylinder; the uneven hot spots have to have some undesired effect on power. Who disagrees that however small the amounts of power Triumphs produce, you want all the performance your particular set up can give you.