stallie Posted February 16, 2009 Report Share Posted February 16, 2009 (edited) Does anyone have any tried and true easy ways to turn the crankshaft when checking/adjusting the timing? Thanks in advance. Edited February 16, 2009 by stallie Quote Link to post Share on other sites
PILKIE Posted February 16, 2009 Report Share Posted February 16, 2009 (edited) Hi stallie. A few ways ive used!! 1. Put car in top gear and rock it forwards. 2. Tension fanbelt with one hand while turning fan blade with the other. 3. Fit a socket and ratchet onto the crankshaft/alt pulley nut. 4. Rig up a switch under the bonnet to flick the starter over a bit at a time. Either method will work best if you remove the plugs first to stop compression happening,that makes it easier to turn it over!! You could always start the engine and use a strobe light while turning the dizzy to the right mark! Dave Edited February 17, 2009 by PILKIE Quote Link to post Share on other sites
BrianC Posted February 16, 2009 Report Share Posted February 16, 2009 My preferred method is to select top gear, jack up a rear wheel and turn it. This can be quite accurate and avoids the 'overshoot' problem encountered when rocking the car or turning the engine on the starter. Obviously it's easier with two people (a wheel-turner and a piston/timing-mark-watcher), but perfectly do-able solo. Quote Link to post Share on other sites
grahama Posted February 16, 2009 Report Share Posted February 16, 2009 I used to use the jack it up, top gear, and turn a rear wheel by hand method - pain in the proverbia!l Unless there are two of you, it's turn a bit, go and look, turn a bit more, go and look, bugger missed it! Then I discovered plugs out and a spanner on the alternator does very nicely. Perfect for millimetric positioning. Quote Link to post Share on other sites
trfella Posted February 16, 2009 Report Share Posted February 16, 2009 Then I discovered plugs out and a spanner on the alternator does very nicely. Perfect for millimetric positioning. Have used the very same method as this when I did my valve clearances. Quote Link to post Share on other sites
Mike C Posted February 16, 2009 Report Share Posted February 16, 2009 I tension the fan belt by pushing one side and turn the fan very slowly to rotate the engine if I leave the plugs in, faster with the plugs out.Depends on whether I'm changing the plugs anyway.What I feel is important is to make sure the engine is rotated in the normal operating direction so that all clearances in the distributer drive are taken up in the correct direction. Quote Link to post Share on other sites
Tom Fremont Posted February 16, 2009 Report Share Posted February 16, 2009 I tension the fan belt by pushing one side I don't get this part ( even after seeing it twice on this thread ). My 250s turn over just fine using the fan blade as handle. As for the alternator method, I did this once and felt the strain on the belt was far more than it was designed to take Quote Link to post Share on other sites
88V8 Posted February 16, 2009 Report Share Posted February 16, 2009 (edited) As for the alternator method, I did this once and felt the strain on the belt was far more than it was designed to take Well, it depends on your muscles. Driving the 55A alternator some folks fit, the belt has to transmit 660W, add in the water pump, must total a good horsepower = 550 ft lb which I guess is way more than the average human arm can muster. So if the belt will rotate the engine, fear not, rotate away. Ivor Edited February 16, 2009 by 88V8 Quote Link to post Share on other sites
Tom Fremont Posted February 16, 2009 Report Share Posted February 16, 2009 Well, it depends on your muscles. Driving the 55A alternator some folks fit, the belt has to transmit 660W, add in the water pump, must total a good horsepower = 550 ft lb There being 746W to the HP I get 4.6 ft-lb @ 1000 rpm As for the torque required to rotate the crank I'd say it's about 5-10 ft-lb from cold rest. Don't know of any TRs yet ( unless Alec can set me straight with a TR8 ) that will produce anything like 550 ft-lb, and I doubt we would trust a fan belt to transmit that Quote Link to post Share on other sites
Alec Pringle Posted February 16, 2009 Report Share Posted February 16, 2009 Sorry Tom, can't give you any torque figures for the big blighters . . . . . the production SD1 Vitesse had around 190bhp and 220ft/lbs of torque from 3.5 litres. The TR8 Turbo Le Mans put out close to 500bhp in its original high compression format, more like 450bhp latterly with lower compression and higher boost, but I don't have torque figures. That's 3.5 litre twin turbo. The TR8 Drag Car in its final Rovercraft 4.5 litre twin turbo form put out 730bhp at the flywheel on petrol. The current 4 litre normally aspirated engine puts out rather less . . . . at least 350bhp on straight petrol, but then there's two stages of NoS to go which takes it to probably 500bhp. Of course you could run either engine on dope fuel rather than petrol . . . . But again, I don't know torque figures. Sorry about that ! Cheers, Alec Quote Link to post Share on other sites
foster461 Posted February 16, 2009 Report Share Posted February 16, 2009 I don't get this part ( even after seeing it twice on this thread ). My 250s turn over just fine using the fan blade as handle. As for the alternator method, I did this once and felt the strain on the belt was far more than it was designed to take In my case no mechanical fan and no easy access to the crank bolt so the alternator is the next available pulley to rotate the engine with. Quote Link to post Share on other sites
88V8 Posted February 17, 2009 Report Share Posted February 17, 2009 There being 746W to the HP I get 4.6 ft-lb @ 1000 rpm As for the torque required to rotate the crank I'd say it's about 5-10 ft-lb from cold rest. Don't know of any TRs yet ( unless Alec can set me straight with a TR8 ) that will produce anything like 550 ft-lb, and I doubt we would trust a fan belt to transmit that So, another addition, not only do we have bigger gallons in England, we also have bigger horses Or perhaps there was an arithmetical inexactitude in my observation Ivor Quote Link to post Share on other sites
Mike C Posted February 17, 2009 Report Share Posted February 17, 2009 Tom,I wrote the above reply from memory before leaving for work.The term "pushing one side" meant one side of the belt triangle to increase belt tension and stop slip.That said I just tried rotating the engine with the belt tensioned "as is" and it will rotate slowly given the force that can be applied to the small plastic fan.I have engine bored to 2.7 litres with high compression pistons and find it difficult to rotate quickly against the engine compression. Quote Link to post Share on other sites
stallie Posted February 17, 2009 Author Report Share Posted February 17, 2009 Wow, I opened a can of worms there! Thanks for all the replies - I'll give them a go. Quote Link to post Share on other sites
Goswell Posted February 17, 2009 Report Share Posted February 17, 2009 I'm glad you opened the can as I'm going to do my valves this weekend and having removed the plugs and found moving anything by hand doesn't work, I was wondering where to go next. Perhaps with the injectors out it maybe easier ! Quote Link to post Share on other sites
PILKIE Posted February 17, 2009 Report Share Posted February 17, 2009 I'm glad you opened the can as I'm going to do my valves this weekend and having removed the plugs and found moving anything by hand doesn't work, I was wondering where to go next. Perhaps with the injectors out it maybe easier ! Removing the injectors wont relieve cylinder compression,or relieve tight engine,which are the main causes of things feeling tight! Sometimes it helps to add a long lever with a socket bar attachment on the alt or crank pulley!! Quote Link to post Share on other sites
stallie Posted February 18, 2009 Author Report Share Posted February 18, 2009 (edited) Thanks for the advice - a combination of both worked well working alone. I'll post this for the benefit of others. I removed all the plugs except #1. Then I jacked up the rear right (at the bend in the frame just in front of the rear door post) so it was just clear of the ground, with car in 4th gear. I found that I could rotate the tyre easily, but a pain to try and do it accurately (solo). What I did was mark the tyre with chalk and worked out how many turns before it flashed again (about 1.3 wheel turns). Then on about 1.2 turns I went to the alternator and using a 15/16 socket was able to turn it easily, though it kept slipping inside the belt. The most effective place to pull on the belt to get tension seemed to be pulling outwards between the alternator and the fan at the same time as turning the nut on the alternator. Pushing in was less effective. Edited February 18, 2009 by stallie Quote Link to post Share on other sites
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