Julian Mullins Posted May 31, 2020 Report Share Posted May 31, 2020 (edited) Hi All No matter what I try, my engine still runs on. 72 TR6 CP car fitted with twin SU’s, electronic ignition, a kenlow fan and an anti running on valve fitted by a previous owner. Engine rebuilt, new everything bar cam and pushrods, unleaded head. Dizzy re built by dizzy Dr.. I’m confident I’ve found true TDC and timing set, rebuilt carbs set up and balanced. Car pulls like a train and is running better than ever until I turn it off when it just keeps going, spluttering and coughing until it eventually gives in. I am thinking I might have a hot spot causing unspent fuel to ignite. So, dare I mention it, I might try Evans Waterless Coolant as I have run out of ideas. Any thoughts ? Thanks in anticipation. Julian Edited May 31, 2020 by Julian Mullins Quote Link to post Share on other sites
RobH Posted May 31, 2020 Report Share Posted May 31, 2020 Using Evans will make your hot spot even hotter Julian. Nothing can shift heat as well as water can - it is just physics and this is one case where you should follow the science. The specific heat of glycol is about half that of water so you would need twice as much flow to shift the same amount of heat. There have been instances where cooling fans spinning down can produce enough voltage as generators to allow an engine to keep running. Are you sure this isn't something like that ? Quote Link to post Share on other sites
stuart Posted May 31, 2020 Report Share Posted May 31, 2020 Double check your timing and what fuel pump are you using? Above advice about Kenlowe windmilling down can be relevant too. Stuart. Quote Link to post Share on other sites
Opie Posted May 31, 2020 Report Share Posted May 31, 2020 Can you send us a close up of one or all of your plugs? Quote Link to post Share on other sites
Julian Mullins Posted May 31, 2020 Author Report Share Posted May 31, 2020 1 hour ago, RobH said: Using Evans will make your hot spot even hotter Julian. Nothing can shift heat as well as water can - it is just physics and this is one case where you should follow the science. The specific heat of glycol is about half that of water so you would need twice as much flow to shift the same amount of heat. There have been instances where cooling fans spinning down can produce enough voltage as generators to allow an engine to keep running. Are you sure this isn't something like that ? Thanks. I had thought some time ago that it could be the fan so I rewired it through a relay and it did cure it for a while, perhaps I should look at it again. You also confirmed my worries over Evans. Quote Link to post Share on other sites
Julian Mullins Posted May 31, 2020 Author Report Share Posted May 31, 2020 1 hour ago, stuart said: Double check your timing and what fuel pump are you using? Above advice about Kenlowe windmilling down can be relevant too. Stuart. Timing checked and double checked. Fuel pump is an SU and runs through a pressure regulator. How might that affect things ? Quote Link to post Share on other sites
Julian Mullins Posted May 31, 2020 Author Report Share Posted May 31, 2020 50 minutes ago, Opie said: Can you send us a close up of one or all of your plugs? Next time I’m fettling I will. Quote Link to post Share on other sites
ntc Posted May 31, 2020 Report Share Posted May 31, 2020 Needless to say but check for air leaks Quote Link to post Share on other sites
Peter Cobbold Posted May 31, 2020 Report Share Posted May 31, 2020 (edited) If the radfan isn't powering the ignition, I'd fit a set of colder running plugs. https://www.ngkntk.in/ngk-technology/importance-of-heat-range/ Some manufacturers use reverse numbering ! Edited May 31, 2020 by Peter Cobbold Quote Link to post Share on other sites
DRD Posted May 31, 2020 Report Share Posted May 31, 2020 Julian, what fuel are you using? Daz Quote Link to post Share on other sites
dingle Posted May 31, 2020 Report Share Posted May 31, 2020 Keep the idle speed as low as possible (below 1000 rpm) may help. Berry Quote Link to post Share on other sites
BlueTR3A-5EKT Posted May 31, 2020 Report Share Posted May 31, 2020 2 hours ago, Peter Cobbold said: If the radfan isn't powering the ignition, I'd fit a set of colder running plugs. https://www.ngkntk.in/ngk-technology/importance-of-heat-range/ Some manufacturers use reverse numbering ! Interestingly here Triumph fitted an hotter plug (N12Y) on carb spec engines in some of the saloon cars with the 6 cylinder engine. I' m with you go colder on the plugs and lower the tick over as far as possible. Peter W Quote Link to post Share on other sites
astontr6 Posted May 31, 2020 Report Share Posted May 31, 2020 5 hours ago, Opie said: Can you send us a close up of one or all of your plugs? You make a good point, if the timing is correct I would suspect that it may have or is still running rich and has a number of hot spots in the cylinder head caused by carbon build up which is causing the running on. What plugs are you using? Bruce. Quote Link to post Share on other sites
mtrehy Posted May 31, 2020 Report Share Posted May 31, 2020 I've had run on with efi caused by voltage from alternator warning light circuit holding aftermarket relay closed. Putting a diode inline sorted it Quote Link to post Share on other sites
Stagpowered Posted May 31, 2020 Report Share Posted May 31, 2020 Is the anti run on valve actually working? Neil Quote Link to post Share on other sites
Mike C Posted May 31, 2020 Report Share Posted May 31, 2020 Most times this has happened to me on older carbureted cars its been the butterflies not closing correctly or an air leak. Quote Link to post Share on other sites
DRD Posted June 1, 2020 Report Share Posted June 1, 2020 8 hours ago, Stagpowered said: Is the anti run on valve actually working? Neil Good point and plumbed in correctly. I've got one and sometimes the solenoid sticks when it gets hot. Quote Link to post Share on other sites
DRD Posted June 1, 2020 Report Share Posted June 1, 2020 10 hours ago, BlueTR3A-5EKT said: Interestingly here Triumph fitted an hotter plug (N12Y) on carb spec engines in some of the saloon cars with the 6 cylinder engine. I' m with you go colder on the plugs and lower the tick over as far as possible. Peter W I've tried BP7ES and they quickly fouled up and I got misfiring. Quote Link to post Share on other sites
Z320 Posted June 1, 2020 Report Share Posted June 1, 2020 (edited) I know the story about electric fans producing voltage while the ignition is off. Isn't the electric fan not only spinning when needed? How can it then cause running on the engine "every time" or often? Julian, this should be easy to test: make shure the electric fan is not spinning when you switch off the ignition. What happens, please? I guess it is running on anyway.... Edited June 2, 2020 by Z320 Quote Link to post Share on other sites
barkerwilliams Posted June 1, 2020 Report Share Posted June 1, 2020 When it is running on turn on the wipers,(really!) does it stop instantly? Wipers take power and kill the voltage powering the ignition if it is an electrical / fan/ problem. If so a simple diode is needed to correct the problem. Alan Quote Link to post Share on other sites
Z320 Posted June 1, 2020 Report Share Posted June 1, 2020 If this is a problem why don't supply the fan direct by the battery, this is terminal A or A1 on the 4 cylinders? And not by the ignition switch. This would have the benefit to have the fan still running on while the ignition is already off while the hot engine still heats the coolant up? Just a question, I use the fan on the crankshaft extension, works always and safe. Quote Link to post Share on other sites
barkerwilliams Posted June 1, 2020 Report Share Posted June 1, 2020 Julian, I would suspect that your Kenlow fan may be the issue, possibly the rear bulb earths. Attached is a document I put together on what I have discovered for "electrical" running-on issues as opposed to a hot engine running-on. Have a read and if it is something else please let me know and I can add to my document. Regards, Alan Running on.docx Quote Link to post Share on other sites
Robert Price Posted June 2, 2020 Report Share Posted June 2, 2020 I bought a TR6 fitted with HS6 SU's its injection system came with the car. However it ran on badly, standard fan and anti run on valve fitted. I decided to refurbish the injection and refitted it to the car, the running on was gone. Having owned MGB's as well for some reason some run on others do not so you may have difficulty in stopping it. However I would try as suggested a colder plug and high octane fuel as it can be compressed more before detonation than lower octane fuel, check the plug colour to see if it is running too hot, reduce tickover to 650/700 max you could retard the ignition slightly if all else fails. I doubt messing with fans and coolant will produce a cure but nothing to lose I guess. good luck. Rob Quote Link to post Share on other sites
Z320 Posted June 2, 2020 Report Share Posted June 2, 2020 (edited) for my HS6 carbs on my TR4A I made my own "anti run system", based on Mercedes-Benz construction with 2 Pierburg valves. This works lovely. Edited June 2, 2020 by Z320 Quote Link to post Share on other sites
Stagpowered Posted June 2, 2020 Report Share Posted June 2, 2020 Retarding the ignition generally makes things worse as the engine will run hotter at idle. When the ignition is switched off the sparks stop regardless of timing. Advancing the timing might work as it generally increases idle speed meaning that the throttle stop can be wound back a bit more to keep the rpm correct. The only problem with this is that with a PI compression ratio you won't get much advance without running into pinking problems. Does your distributor have vacuum advance as the carb cars did but PI didn't. Vacuum advance makes the engine run more efficiently, less heat generated therefore less likely to run on. If you take the vacuum advance directly from the inlet manifold rather than the spigot on the carb you will get quite a lot of advance at idle where you normally get non as the spigot is blocked by the throttle butterfly at idle. The extra advance will allow you to wind the idle speed down on the throttle stop, but won't make it pink like advancing the static timing. The original engine in my TR 250 was converted to injection using 132 PI saloon bits. To begin with it had no vacuum advance, but fitting one made a big difference Neil Quote Link to post Share on other sites
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