Phil Horsley Posted June 28, 2015 Report Share Posted June 28, 2015 Hi Folks, now where am I going wrong, static timing my TR250, first set pulley at 10 degrees BTDC with no.1 on compression stroke, rotor arm is now at approx 6 o'clock turn dizzy so points just opening and fix in place. Start engine perfect, engine running circa 2k revs, check timing on no.1 with strobe, TDC mark at 8 o'clock scratching head, retard engine slightly to reduce revs, do it all again as I must have made an error as TDC Mark should be top of pulley under strobe, same result, so what am I doing wrong, As far as I know the dizzy has never been out and it ran AOK before I had the car body restored, any ideas pleas? Quote Link to post Share on other sites
ctc77965o Posted June 29, 2015 Report Share Posted June 29, 2015 When static timing you say rotor at 6oclock, is that where No 1 lead is on the dizzy cap?? You say your dynamic /strobe pulley mark is 8oclock which is ~50 degrees BTDC and beyond what's reasonable for the combine effect of centrifugal&vacuum advance Quote Link to post Share on other sites
TriumphV8 Posted June 29, 2015 Report Share Posted June 29, 2015 So the cam lobe/cam lobes side you used for setting static timing is not the lobe that is in use to time number one ignition. Sounds like you approached the cam for opening the points from the wrong side or there was major play in the drive you did not fiddle out. Quote Link to post Share on other sites
Peter Cobbold Posted June 29, 2015 Report Share Posted June 29, 2015 (edited) +1 with Andreas. The disy cam rotates anticlockwise so set the points to open at 10-12BTDC on the leading slope of the cam, not the closing slope. Peter Edited June 29, 2015 by Peter Cobbold Quote Link to post Share on other sites
Phil Horsley Posted June 29, 2015 Author Report Share Posted June 29, 2015 Hi Folks, yes the No.1 is at 6 o'clock, and I'm sure I'm the right side of the cam for anticlockwise, I can't add pictures for some reason I'll contact admin!!! Quote Link to post Share on other sites
Peter Cobbold Posted June 29, 2015 Report Share Posted June 29, 2015 Is it one of the new fangled strobes where you dial in the timing? I much prefer one that just flashes when HT in #1 lead is live. Peter Quote Link to post Share on other sites
Phil Horsley Posted June 29, 2015 Author Report Share Posted June 29, 2015 Hi Peter Normal strobe on no.1 flashing when live, powered by the battery. Cheers Phil Quote Link to post Share on other sites
ctc77965o Posted June 30, 2015 Report Share Posted June 30, 2015 So, the problem is just the strobe measurement? It's running ok, just needs the idle lowering to something more reasonable. Why not attach your strobe to each plug wire in turn, the one running 15BTDC at 1000rpm must be number one....crank pulley marks must be ok as you have statically timed it successfully.... Quote Link to post Share on other sites
Peter Cobbold Posted June 30, 2015 Report Share Posted June 30, 2015 Phil, Might be the timing mark in wrong place. So ignore the marks. Slowly turn the disy a few mm to and fro at tickover - keeping below 1000rpm - unitl you get optimum rpm position. If it pinks upon sudden flooring the throttle take off a couple of dergrees at a time until it doesnt. Peter 2k rpm will bring in most of the centrifugal advance. But not to 8 o'clock, which is about 55 btdc Unless the advance springs are weak. Is the disy moving plate anchored by the spring to the knurled adjuster and vac capsule link. Quote Link to post Share on other sites
Phil Horsley Posted June 30, 2015 Author Report Share Posted June 30, 2015 Hi all, thanks for your advice, took it to my local guy, he told me he timed it by ear, and set the carbs to his meters without compromising the engine running, took it for a 90 mile run tonight so a good shake down, drove very nicely, temperature oil pressure aok and a nice smooth tick over when I got back of circa 850 revs, so hopefully there, just want to check the fuel pressure now as there's a Facet red top on it, I put a fuel master on but I've loaned my gauge to a mate 90 miles away, ho hum!!!!! Thanks again. P.S. what would cause a shuddering/vibration in the drive chain , overdrive reliefs it but also in you flick the OD in/out quick it goes away in fourth gear, its seems to be around 50/60 mph, I'm wondering if its prop, maybe need a packing with more grease, over to you guys please? Phil Quote Link to post Share on other sites
Phil Horsley Posted June 30, 2015 Author Report Share Posted June 30, 2015 PPS timing mark circa 10/11 o'clock now, so much closer, a few years ago, TR Bitz swapped the dizzy with preset advance dizzy (no vacuum), my friend tells me by the number (41212 I think) its for a early TR5 injection, so maybe having no vacuum is giving this strange reading on the pulley or as you say Peter, they are inaccurate? Quote Link to post Share on other sites
Peter Cobbold Posted July 1, 2015 Report Share Posted July 1, 2015 (edited) PPS timing mark circa 10/11 o'clock now, so much closer, a few years ago, TR Bitz swapped the dizzy with preset advance dizzy (no vacuum), my friend tells me by the number (41212 I think) its for a early TR5 injection, so maybe having no vacuum is giving this strange reading on the pulley or as you say Peter, they are inaccurate? Phil, The TR5 disy has a centrifugal advance curve that will work OK on the carb engine. The vacuum advance capsule would work but was never on the PI engines connected up. On your carb engine you can connect up the present disy vacuum advance capsule to the throttle edge take-off, here: http://0.tqn.com/w/experts/MG-Car-Repair-3786/2010/07/SU-HIF44-Carb.jpg This provides vacuum only at cruise to advance the spark for better fuel economy. It has no effect at tickover and no effect at wide throttle openings - the vacuum is there only at small throttle openings. If the strobe is now reading 10BTDC at 850rpm tick-over that is about right. Because theres no centrifugal advance and no vacuum advance so the spark happens at the static value, around 10-12BTDC - which is what youve got . Timing by ear really does work !! Peter I use one of these to regulate fuel pressure to the SU to around 2-3psi: http://www.fuelpumpsonline.co.uk/sytec-flo-pro-fuel-pressure-regulator-carburettor-1-5psi-30-p.asp PS I would start a new thread for the vibration query . Edited July 1, 2015 by Peter Cobbold Quote Link to post Share on other sites
Phil Horsley Posted July 4, 2015 Author Report Share Posted July 4, 2015 Thanks again Peter, really useful advice ) Quote Link to post Share on other sites
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