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Post by Nick RS on May 14, 2013 17:47:19 GMT
Hello David, Thanks for putting me right, seems obvious now but I was really scratching my head last night. I can't see the pointers from the other side of the pulley so will have to carry on from the wrong side so as to speak. There five pointers, will these cover 20 degrees of advance? I need to sort out a tachometer of some sort as the one fitted to the car is hopelessly inadequate and never reads much over 2000rpm whatever speed the car is doing. I'll report back on the readings when I get one but just from listening by ear I think my idle speed when the engine is warm is over 1000 but probably a lot less than 1500.
As for your other points. The engine doesn't take too much cranking from cold and almost none at all when warm. It pulls strongly from just about any speed and there are no flat spots. The fastest I have driven or want to go is 70mph. I heard pinging under load when I accidently put some 95 unleaded in but 50 miles later I filled up with 97 and added the last of my tetraboost lead additive and am currently on equivalent 99 octane and the the car runs fine with no pinging. This is making me wonder if the ignition has been advanced a little to get the most out of this fuel - the previous owner said the car was much happier using 97 + additive. Nick
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Post by Penguin45 on May 14, 2013 19:57:29 GMT
I have the opposite problem - it runs like a pig on 97/98! Standard 95 and Valvemaster without a booster suits mine fine. It is worth taking a minute and painting the pointers white and picking out the line on the pulley as well - they become much more visible. Pointers from the pulley side. The timing on mine settled at just before 12 oBTDC - still need to turn the idle down a smidge. Chris.
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Post by Nick RS on May 14, 2013 20:51:55 GMT
Good call Chris, The line on the pulley is painted though like the marks on the pointers has yellowed over time. I'll redo them when I get round to recording the advance at various rpm. This slightly blurred pic shows that the marks really won't be visible from the other side of the pulley so I can't replicate the diagram in the manuals. BTW I got to grips with Flickr. Only part of the URL code is required to upload the photos; good old Google. Nick
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Post by dave1800 on May 15, 2013 1:00:45 GMT
Chris, thanks for posting the timing mark diagram and clarifying there are 5 pointers including TDC. I had looked at my w/s manual which just shows just 4 pointers at TDC, 5,10,15 degrees BTDC and couldn't quite make out how many I could see in Nick's photo. Nick. Now I see there are 5 pointers, (TDC,5,10,15 and 20 degrees BTDC). I believe therefore that your timing at your car's idle is actually 17 degrees BTDC - but what is the idle RPM? If it is 1000rpm then I think you have 2 degrees over advance, if it is 1500rpm then it is a couple of degrees retarded, neither scenario being significant. However, if the idle is correct at 700rpm then this would indicate the ignition being over advanced by some 5 degrees. Your tacho is certainly strange and my advice would be to disconnect it just in case it has developed an odd internal fault that could put additional load on the ignition system - unlikely but better to be safe. I think the next move is to get an accurate idle RPM reading. Unless the ignition is 5+ degrees over advanced at idle then there is another reason for the high idle speed. As suggested earlier check for any air leaks and ensure the throttle and choke cables aren't holding the throttle butterfly open. Try disconnecting them. If you remove the air cleaner and lift the carb piston with your fingers, using a mirror you should be able to see if anyone has fitted a later carb butterfly which has a spring loaded valve in it. If this fails it can have the same effect as opening the throttle. The non valved butterfly is a plain disc. The crankcase breather valve diaphragm should also be checked for splits or damage. Regards David quote author=nickrs board=talk thread=408 post=3711 time=1368564715]Good call Chris, The line on the pulley is painted though like the marks on the pointers has yellowed over time. I'll redo them when I get round to recording the advance at various rpm. This slightly blurred pic shows that the marks really won't be visible from the other side of the pulley so I can't replicate the diagram in the manuals. BTW I got to grips with Flickr. Only part of the URL code is required to upload the photos; good old Google. Nick[/quote]
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Post by dave1800 on May 15, 2013 1:16:08 GMT
Now why couldn't yours be normal!! What are other members' exeriences with fuel ratings? David I have the opposite problem - it runs like a pig on 97/98! Standard 95 and Valvemaster without a booster suits mine fine. Chris.
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Post by Nick RS on May 15, 2013 18:34:22 GMT
Digital Tachometer ordered and on its way. I'll report back with some proper stats after the weekend. Nick
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Post by Penguin45 on May 15, 2013 23:42:43 GMT
What sort of tacho is fitted, Nick? 123 site suggests that the Smiths RVI tacho won't run properly from their distributor.
Chris.
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Post by dave1800 on May 16, 2013 1:06:36 GMT
I believe the 123 ignition will only work with voltage triggered tachos. The RV1 and many of that era are current driven and without an adaptor circuit require the current to be provided by points closing. The 123 varies the dwell time so looks quite different to points. This has upset a number of MGB and Triumph owners who want to keep their cars' appearance original. As I mentioned earlier, best to remove your non functioning tacho from the 123 wiring. Regards David What sort of tacho is fitted, Nick? 123 site suggests that the Smiths RVI tacho won't run properly from their distributor. Chris.
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Post by Nick RS on May 16, 2013 13:01:30 GMT
The tacho fitted is a modern Durite item, you can probably guess what is coming...
I had been thinking that whenever I looked it when driving it only ever seemed to read about half what I was expecting. The Durite catalogue lists it as suitable for 4,6 or 8 cylinder engines and yes, I have now discovered the little switch on the back of the instrument. I'm not really covering myself with glory this week am I?
Idle speed when the engine is warmed up is 1300 to 1400rpm. I will do the other tests over the weekend.
Nick
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Post by dave1800 on May 17, 2013 1:51:04 GMT
Hi Nick, don't worry we've all been there! Are you sure your tacho doesn't have a switch for 2 cylinder engines as your idle is twice what it should be I think first thing is to connect the replacement tacho. It is just possible that the tacho is responding in an odd way to the 123 ignition system. If it really is that high then I would have thought the car would be very difficult to drive slowly in traffic? I don't think an air leak would make it run that high, maybe an increase of 200 rpm at most. Perhaps you can drive the car with 1500 rpm on the tacho in top gear and check the speedometer. it should read around 28mph. If this is OK you have discounted the 123 ignition / tacho match. Then you need to look for something holding the throttle open. Ensure there is a gap between the fast idle screw and the throttle cam when the choke is fully in. If you pull out the choke you will see how it opens the throttle. Next disconnect or loosen the throttle cable and try and close the throttle, don't use much force - unscrew the idle adjusting screw until there is clearance. Good luck! Regards David The tacho fitted is a modern Durite item, you can probably guess what is coming... I had been thinking that whenever I looked it when driving it only ever seemed to read about half what I was expecting. The Durite catalogue lists it as suitable for 4,6 or 8 cylinder engines and yes, I have now discovered the little switch on the back of the instrument. I'm not really covering myself with glory this week am I? Idle speed when the engine is warmed up is 1300 to 1400rpm. I will do the other tests over the weekend. Nick
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Post by threelitre on May 17, 2013 8:44:48 GMT
Now why couldn't yours be normal!! What are other members' exeriences with fuel ratings? David I have the opposite problem - it runs like a pig on 97/98! Standard 95 and Valvemaster without a booster suits mine fine. Chris. Both the 1800 S and 3litre are everything but happy with 95 RON fuel. Both are run in factory tune. Regards, Alexander
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Post by threelitre on May 17, 2013 8:56:06 GMT
I believe the 123 ignition will only work with voltage triggered tachos. The RV1 and many of that era are current driven and without an adaptor circuit require the current to be provided by points closing. The 123 varies the dwell time so looks quite different to points. This has upset a number of MGB and Triumph owners who want to keep their cars' appearance original. As I mentioned earlier, best to remove your non functioning tacho from the 123 wiring. Regards David What sort of tacho is fitted, Nick? 123 site suggests that the Smiths RVI tacho won't run properly from their distributor. Chris. I have found that the old RVI tach fitted to a 1300 works well with a Lucas electronic distributor from a Maestro. It does not show enough rpm in the higher range, but so did it before with the original installation - most likely due to age. The way it is connected has just been carried on to the modern ignition, by feeding the coil charge wire from the distributor's ignitor unit through to the tacho, around it's excitation coil and than back to the ignition coil. I cannot see why this should not work with any ignition system using a single coil and no wasted sparks. Regards, Alexander
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Post by dave1800 on May 17, 2013 11:11:37 GMT
Hi Alexander
I believe the 123 ignition uses variable dwell so at an idle of 750rpm for example it is turning the coil on for maybe 3.5 m/s and off for 36.5 m/s if my maths are correct. The 25D4 distributor would turn the coil on for 24m/s and off for 16 m/s at this engine speed.
The coil only needs to be turned on for about 3.5 m/s to fully charge. At 5000 rpm the distributor will turn the coil on for 3.6 m/s and off for 2.4 m/s, still just able to charge the coil fully.
This way the 123 ignition only charges the coil with what it needs to release its energy at the firing point whereas the distributor with its fixed dwell wastes the excess energy as heat in the coil at lower RPM.
I think that the RV1 and other current driven tachos rely on having a fixed dwell to function. Your electronic Lucas distributor may well have used a fixed dwell. I know some of the early electronic Bosch distributors using a hall vane switch still had a fixed dwell determined by the vane dimensions.
Hope this makes some sense?
Regards
David
[/quote]
I have found that the old RVI tach fitted to a 1300 works well with a Lucas electronic distributor from a Maestro. It does not show enough rpm in the higher range, but so did it before with the original installation - most likely due to age. The way it is connected has just been carried on to the modern ignition, by feeding the coil charge wire from the distributor's ignitor unit through to the tacho, around it's excitation coil and than back to the ignition coil.
I cannot see why this should not work with any ignition system using a single coil and no wasted sparks.
Regards,
Alexander[/quote]
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Post by Nick RS on May 19, 2013 20:00:16 GMT
Had a good old tinker over the weekend. I was inclined to retard the timing a bit but couldn't shift the distributor, maybe a good thing as I am sure the previous owner knew exactly what he was doing and set it up properly. I had a play with the carb. It was dying away under the lifting pin test so I have richened the mixture a bit. The mixture control cam was not clear of the fast idle screw so I corrected that. Finally I tightened everything up between the carb and the engine and all together this has dropped the rpm to about an indicated 1000 and stopped the running on. The car went just as well as ever on a road test including motorway speeds. I tried to make it pink but there was nothing.
I know it's not perfect but think I'll leave as is for a bit to see where it settles.
Nick
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Post by dave1800 on May 20, 2013 0:43:08 GMT
Hi Nick Good to hear you are almost there. I wouldn't suggest touching the timing until you have taken some advance v rpm measurements from idle v up to 4000rpm (vacuum pipe disconnected and plugged) and even then come back to the forum to see if between us we can advise or point you in the right direction. Do you have any info as to possible engine mods eg camshaft that may have been made as these affect the settings. Regards David Had a good old tinker over the weekend. I was inclined to retard the timing a bit but couldn't shift the distributor, maybe a good thing as I am sure the previous owner knew exactly what he was doing and set it up properly. I had a play with the carb. It was dying away under the lifting pin test so I have richened the mixture a bit. The mixture control cam was not clear of the fast idle screw so I corrected that. Finally I tightened everything up between the carb and the engine and all together this has dropped the rpm to about an indicated 1000 and stopped the running on. The car went just as well as ever on a road test including motorway speeds. I tried to make it pink but there was nothing. I know it's not perfect but think I'll leave as is for a bit to see where it settles. Nick
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