nigxl
Part of things
Posts: 786
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Dec 12, 2016 19:49:35 GMT
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Been doing a bit of checking on these modules and I think my coils primary resistance may be too low, this may have killed it. Or it may have been connected incorrectly which again kills it. Or it may have been jump started with a flat battery which again may kill it. I suppose that's what you get when you buy a non runner.............
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Dec 12, 2016 22:58:27 GMT
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so did you check the coil?
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nigxl
Part of things
Posts: 786
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Yeah I did, it was about 1.3 ohms as I recall..
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ChasR
RR Helper
motivation
Posts: 10,251
Club RR Member Number: 170
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I'll have to check the YouTube video but I'll see. I normally check the dwell angle however but you need a suitable multimeter or dwell meter to check this figure. They are around £30 from Maplin and being electronic is meant to make it different to read but I normally get a consistent figure. That said, seeing as it's a non-runner when you bought it and I am assuming this is the first time you have run the engine? If it were me I'd check the rest of the car out in the following order: -Valve clearances ; these IMO make a bigger difference than people think; you can make an old car purr just like a modern by doing this as a first step -Compression. Being an old engine it may have succombed to Valve Seat Recession (VSR). If this is off no end fiddling will make the engine run right. The above step if any of the clearances are miles off will help in curing this. -Ignition. This is looking good I must say for now. - you could rule out the earth strap by putting a jumper cable between the engine and the body of the car. I normally keep the mini earth straps inside the dizzy when I do an electronic conversion but I do believe alot of people bin them. I almost always check my ignition timing with a timing gun. Alot of the cars I have bought with them checked by ear tend to pull well, but also normally run strangely at the bottom (a mega sharp throttle being one that causes kangarooing of the car) and also have the side effect of coming close to failing the emissions if a post '75 car. -Carbs ; This is the final step. I reckon your carbs should be fine but I'd still check them for leaks at the spindles. I have managed to make an engine run smoothly at idle with worn spindles but then suffer a little at the top end ; it's always a compromise when you have an air and effectively a vacuum leak present. Apologies if it looks like I am preaching, especially if you have checked the above. But with an unknown car, even on a running one you never know what you are buying. That said, I like how you are going about the car and fingers crossed it should go smoothly .
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Last Edit: Dec 13, 2016 9:18:14 GMT by ChasR
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nigxl
Part of things
Posts: 786
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Dec 13, 2016 11:23:35 GMT
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Thanks Chas, I think I've pretty much covered all of the above. I rebuilt the carbs as they were in such a manky state including new spindles and bushes. Compression is even across all four cylinders and tappets have been set, all were pretty much there or there abouts. I have set the carb mixtures with a colortune spark tester and am getting good blue flashes across both carbs since adjusting mixture screws. Have also balanced them with a meter as well as by ear and they seem spot on. The problem I am getting seems to be an intermittent spark as seen by using an inline spark tester. My coil was a very low 0.8 ohm item which may have damaged the ignition module, that and I had a very poor -ve connection to the coil. So I've ordered a new coil, electronic ignition and lucas dizzy cap as the caps I have bought just seem to want to eject the centre electrode every time they are so much as looked at. I was going to try the points set up on the dizzy that is fitted to the donor car just to try and prove the electronic ignition but it has become seriously attached to the block. Currently soaking in penetrant.
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ChasR
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Dec 13, 2016 11:39:04 GMT
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No worries, but forums can be a tricky place to communicate ; one can grab the wrong end of the stick . Is your old coil 0.8 or the current one? I've found new coils have given me more issues unless they are Bosch Blues or in your case a Bosch/Beru Red but there reports of even the Bosch stuff not being what they once were. Intermittent spark? If the negative is bad I'd try sorting that as a first step. On my 205 I had an engine that would run fine one minute or dog rough the next few minutes, which was down to a crimped terminal coming loose at the coil. I'd also check out the plugs. I only generally get NGKs but the odd set from dubious suppliers have caught me out before. I have been OK with Bosch. My Stag had a misfire at high RPM ; Everyone told me the Holley was at fault but it did the same thing on the Strommies! It took a year to diagnose that fault. On the M3 a couple of the clearances were only out by .02mm or less. It was surprising the difference it made to the smoothness and power of the engine, and dare I say it, even the cold starting after being left an age. It's a shame there are so many curse word parts out there on the market!
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Last Edit: Dec 13, 2016 11:39:55 GMT by ChasR
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adam73bgt
Club Retro Rides Member
Posts: 4,939
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Dec 13, 2016 12:09:13 GMT
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Just remembered something, may or may not be relevant The later B's have a ballast resistor I believe and the coil needs to be matched accordingly. Is there a potential a coil designed for an early B is being used? Its been a while since I've looked at B ignitions so I can't remember what the potential effects of a dodgy ballast resistor are but it might be something worth checking out
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nigxl
Part of things
Posts: 786
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Dec 13, 2016 13:33:40 GMT
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Just remembered something, may or may not be relevant The later B's have a ballast resistor I believe and the coil needs to be matched accordingly. Is there a potential a coil designed for an early B is being used? Its been a while since I've looked at B ignitions so I can't remember what the potential effects of a dodgy ballast resistor are but it might be something worth checking out Yeah I was reading about that Adam I think it's built into the loom rather than being a stand alone part. It is quite likely that the coil is from an earlier car, but I do have a spare that is 2.3 ohms so I may try that on later if I can retrieve my centre electrode from my pit. The coil that I have been attempting to run the car on had a 0.8 ohm resistance.
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nigxl
Part of things
Posts: 786
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Dec 14, 2016 16:43:29 GMT
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Ok so new 2.3 ohm coil fitted and dodgy POs wiring sorted out and after a bit of spluttering she seemed to be firing on all four nice and evenly. But under higher revs I was getting a backfire intermittently, so a new set of NGKs later and she is now purring. Seems like I may have had a dodgy plug breaking down under load as well as the wrong coil and dodgy wiring. I'm guessing the electronic ignition, coil and cap will now be more expensive spares So the car got a nice oil and filter change now that it's behaving itself. A good day all in with more stuff repaired than broken.
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Dec 14, 2016 19:01:28 GMT
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Ive had 2 after market electronic ignitions fitted to my b in the past, both caused nothing but problems and eventually failed, running points and condenser at the moment, I find myself replacing parts that Ive replaced before down to poor quality, would rather pay more for something that lasts!!
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72 MGB GT 88 Daimler Double Six 89 Rover Mini 91 Nissan Figaro 95 Lotus Esprit S4S 18 Discovery
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Nathan
Club Retro Rides Member
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1978 MGBGT project ( now sold )Nathan
@bgtmidget7476
Club Retro Rides Member 1
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Dec 15, 2016 11:15:08 GMT
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Have to Echo what Monty400k says, when mine was on B-Series power I had the Lumenition optronic system with matched coil. It worked faultless for a year or so then just broke, they replaced it luckily but it happened a year later, I was convinced to upgrade to the Power module by their representative (He based it on my engine at the time being practically Stage-3 not that it should make much of a difference).
The Power unit worked for about 2 years then sure enough it just stopped, at which point I think something in the cars wiring was causing this (it didn't have a stereo and minimal electrics). I had enough throwing money at it so went back to the old points with a rebuilt Dizzy which work perfectly until I decided to go down the transplant route.
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ChasR
RR Helper
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Posts: 10,251
Club RR Member Number: 170
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Dec 15, 2016 14:06:07 GMT
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Good to hear it is sorted.
As for the points, they seem to be made of garbage these days ; I've seen first hand the heels of the points melting on 1-2 year old items and condensors shorting out somehow.
It's a shame quality is not available short of going for something like a Megajolt (even then, good coilpacks are not cheap) or a 123 dizzy, neither of which are cheap.
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nigxl
Part of things
Posts: 786
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Dec 19, 2016 18:30:17 GMT
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Did a bit more today, took the propshaft and stainless exhaust off the donor car. Also took off the gear lever so I should be able to move the blue car under its own steam once all the bits are fitted.
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nigxl
Part of things
Posts: 786
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Dec 20, 2016 11:29:03 GMT
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Anyone removed an overdrive gearbox mounting from one of these? Can it be done with the gearbox still on the car or does the box have to come out first?
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Dec 20, 2016 11:39:48 GMT
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If you mean "Remove the OD unit from the back of the gearbox" then it has to come out of the car. If nothing else, I seem to recall that the gearbox had to be standing on end to re-install the OD unit on the gearbox.
People have been known to cut the crossmember in order to do clutch jobs without pulling the engine and gearbox, but I am not a fan of that move.
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Dec 20, 2016 11:41:13 GMT
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Are you trying to separate the gearbox and overdrive ? if so yes the gearbox has to come out ...
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Last Edit: Dec 20, 2016 11:43:18 GMT by westbay
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Dec 20, 2016 11:44:00 GMT
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Re-read the title...what are you trying to do? Fix the gearbox mount or does the OD unit need repair?
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nigxl
Part of things
Posts: 786
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Dec 20, 2016 14:07:29 GMT
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I just want to remove the mounts with the crossmember from the donor car to fit to the good car. Looks like I may need to drill holes in the member to access the mount nuts.
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Dec 20, 2016 14:50:56 GMT
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I just want to remove the mounts with the crossmember from the donor car to fit to the good car. Looks like I may need to drill holes in the member to access the mount nuts. Actually, you don't. Go ahead and drop the transmission crossmember and let the back of the gearbox rest on the body crossmember. Now, go find a long extension and a flex-joint. Approaching the job from the outboard side of the transmission crossmember, you can get the flex-socket on the gearbox mounts. May want to pull down on the crossmember side a bit to get at stuff. The other trick I have used is to replace the damn things with socket head bolts in order to make this job easier. I know I have a picture of this somewhere. Will try to have a look for it.
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nigxl
Part of things
Posts: 786
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Dec 20, 2016 14:56:56 GMT
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Nice one thanks for that. Unfortunately this isn't over my pit which makes it awkward but not impossible I hope. I've got the outer bolts out and the box is resting on the rear frame so will give this a go tomorrow.
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