mbeano Posted September 15, 2011 Report Share Posted September 15, 2011 can anyone help please? I've got an ex-USA TR6 on twin SU HS6 carbs (converted to RHD). It starts from cold first time. I only need to go to a couple of hundred yards (to the filling station) and it won't restart so it can't be overheating or evaporating the fuel. I've fitted new plugs, points,condenser, coil, new spindles & butterflies in the carbs with all new gaskets. Always had a bit of a problem with it running smoothly but it always used to restart ok. But now, I've got this restarting problem too. I'm running out of options and getting more & more frustrated. Any ideas please?!?!? Quote Link to post Share on other sites
stuart Posted September 15, 2011 Report Share Posted September 15, 2011 Rotor arm? Stuart. Quote Link to post Share on other sites
mbeano Posted September 15, 2011 Author Report Share Posted September 15, 2011 sorry, oh yes and a new rivetless red rotor arm fitted. Quote Link to post Share on other sites
rogerguzzi Posted September 15, 2011 Report Share Posted September 15, 2011 Tank vent(lack of) or fuel pump? Quote Link to post Share on other sites
poolboy Posted September 15, 2011 Report Share Posted September 15, 2011 As Roger suggest. Open the gas cap as a diagnostic. Quote Link to post Share on other sites
Peter Cobbold Posted September 15, 2011 Report Share Posted September 15, 2011 If it wont rstart after a fill-up I dont think its lack of tank vent. So fuel pump as Roger suggests, or clogged fuel filter. On SUs the engine should be smoother than PI. As you have 'always had a bit of a problem with it running smoothly' suggests something basic adrift. Perhaps spark timing. If you have an original, unshaved USA head the compression will be low, maybe 7.75 in the last year ('75 IIRC) . That needs more ignition advance than PI engines - try setting static to say 15 or 20 BTDC and see it it improves. (I have 8.5 CR and use 18BTDC). Do you know what mixture the carbs are giving? what needles and springs are fitted? Quote Link to post Share on other sites
MJH Posted September 15, 2011 Report Share Posted September 15, 2011 I had float level isues on my SU's it was the float needles sticking, could it be that? Quote Link to post Share on other sites
johnny250 Posted September 15, 2011 Report Share Posted September 15, 2011 When it stops, or won't start, whip the top off the back carb float chamber and see if it's got any fuel in it.....if not then fuel pump U/S. Blockage, diaghpram, flap valves or as in my case, top body cracked through from one side to the other...... these carbs would have to be wildly out of tune to prevent running at all. john Quote Link to post Share on other sites
rogerguzzi Posted September 16, 2011 Report Share Posted September 16, 2011 How about valve clearances to small and holding valves open when hot? Quote Link to post Share on other sites
mbeano Posted September 17, 2011 Author Report Share Posted September 17, 2011 thanks to all you guys for these suggestions. I'll work through them and will report back. Quote Link to post Share on other sites
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