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Post by Penguin45 on Nov 12, 2011 1:25:24 GMT
I'm with David here. I'd see if you can find a new rectifier pack at the first opportunity. It's all Lucas stuff, so should be quite easy to find and probably cheap.
In the summer, I did a 360 mile run down to my parents place in Cornwall in 7 hours. After saying hello, I went to check the oil level and noted that the coil was warm, but not hot - I could rest my hand on it quite comfortably.
Chris.
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Post by tommydp on Nov 12, 2011 9:21:30 GMT
Thanks, Chris and Dave! Both the other 1800 and the Marina have points, too. The coil never gets too hot to touch, but I remember when measuring it got significantly hotter than the other crab in the same period of time.
I'm now using the Bosch alternator. It has also been tested fine so I suppose something in the wiring etc is playing it up if the alternators turn out to be the cause of the misfire.
I'll try to feed the coil directly from the battery and have a look at the wiring again. I'm really thinking of getting the behind dash wiring loom out for a check, as well as the connecting plate where the fuses are. The earth points and earth straps in the engine compartment are fine, not so sure about those behind the dash. Are there other earthing points to check out?
Regards, Tommy.
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Post by dave1800 on Nov 12, 2011 10:14:37 GMT
Try wiring the ignition coil directly to the battery as I suggested and take out all of the fuses. If this works and the misfiring stops, then reinsert the fuses one by one while switching on the relevant items connected to them until you find which cause the problem. If it turns out it is the wiring to the ignition coil then you need to trace this back through the ignition switch and the various connectors. As the coil is getting its ground via the contact breaker you need to check the distributor body is soundly earthed (I don't think this is a likely problem) and the wire from the CB to coil and connectors are good. I think that if the problem is electrical, then it is the +ve supply side. Remember just do one thing at the time with car electrics or you could be tearing your hair out! Regards David T I'll try to feed the coil directly from the battery and have a look at the wiring again. I'm really thinking of getting the behind dash wiring loom out for a check, as well as the connecting plate where the fuses are. The earth points and earth straps in the engine compartment are fine, not so sure about those behind the dash. Are there other earthing points to check out? Regards, Tommy. |
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Post by dave1800 on Nov 12, 2011 10:19:04 GMT
Hi Chris Have you checked your dwell with the electronic ignition fitted. I know the Pertronix which looks like yours but costs much more actually controls the dwell with a microcomputer, so it varies with rpm (low at idle increasing as the rev rise). regards David PS like your recent photos - very informative In the summer, I did a 360 mile run down to my parents place in Cornwall in 7 hours. After saying hello, I went to check the oil level and noted that the coil was warm, but not hot - I could rest my hand on it quite comfortably. Chris. |
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Post by tommydp on Nov 12, 2011 10:31:18 GMT
[quote
Remember just do one thing at the time with car electrics or you could be tearing your hair out!
quote]
Luckily, I'm already bald:-) I'll try out your suggestions to coil feed and fuses. The distributor is well earthed.
Tommy:-)
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Post by tommydp on Nov 12, 2011 14:53:57 GMT
Had a go and connected coil directly to battery and removed all fuses. No difference. I tried disconnecting the wire from alternator to battery as it was idling. It's obvious that idle rises when I disconnect it. When I put it back on rpm goes down, as if the alternator is putting a load on the engine.
I notice the lower part of the radiator stays cool while it's running at operatin temperature, while the upper part is too hot to touch. The temperature gauge always stays in the normal area, so suppose this is ok, but being desperate everything comes to my mind.
As it was idling it started missing/ stalling even worse and finally the float chamber flooded... You just got to love this car. The needle and seat is fine, so no obvious reason why it should do this..
Seriously, I'm not sure if I can take all the headaches with this car more. Nothing seems to make sense whatever I do..
Tommy.
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Post by dave1800 on Nov 13, 2011 0:33:11 GMT
Yes!! The alternator IS putting a load on the engine when you connect it electrically - if not you would have discovered free energy! Does the radiator get hot at the bottom after a run. You would expect it to be somewhat hotter at the top, maybe the symptom is due to just running at idle with a low water flow rate - are you happy the radiator core isn't blocked? (I think maybe hang on to the other Crab for a while!) This seems now to be pointing to a fuel issue. If the float, valve and seat is good and there is no dirt or grit, then there is too much fuel pressure. Have you measured the pressure from the fuel pump you now have fitted? Looks like a long winter! regards David I tried disconnecting the wire from alternator to battery as it was idling. It's obvious that idle rises when I disconnect it. When I put it back on rpm goes down, as if the alternator is putting a load on the engine. I notice the lower part of the radiator stays cool while it's running at operatin temperature, while the upper part is too hot to touch. The temperature gauge always stays in the normal area, so suppose this is ok, but being desperate everything comes to my mind. As it was idling it started missing/ stalling even worse and finally the float chamber flooded... You just got to love this car. The needle and seat is fine, so no obvious reason why it should do this.. Seriously, I'm not sure if I can take all the headaches with this car more. Nothing seems to make sense whatever I do.. Tommy. |
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Post by tommydp on Nov 13, 2011 1:14:39 GMT
So you believe the charging circuit and alternator is ok, Dave? I have not checked the radiator after a run. It has been flushed numerous times, does not leak and I have the correct 13 expansion tank cap. Heater works very well, water pump is correct NOS.
Perhaps it's down to fuel again then. At least the miss I have at idle will go away for some time if I rev the engine, and engine will smooth out for some time and just before the flooding starts, the same miss is even more pronounced, finally almost stalling the engine as petrol starts to overflow. The float is from the other crab, which runs fine.. I swapped float lids and float between the two, and the other one runs fine with the one I had in the troublesome too..
This could explain the fact it runs fine for say five minutes as well as the mixture being impossible to get stable and right when hot. When cold started it responds correctly to the lifting pin.
I'm trying out the third petrol pump now, which is a correct NOS SU pump. I have not checked pressure lately, but occasionally when I disconnect the fuel feed pipe at carb, petrol really blows all over out from the pipe as from exessive pressure. I have the correct insulator block between engine block and pump. Perhaps additional washers could make sense?
What else could cause high fuel pressure? As mentinoned tank and steel pipe from tank to engine has not been changed. There's no suction when opening the fuel filler.
Luckily, the Norwegian winter is long, Dave:-) And yes, I know it's late at night here. Saturday and Cuba libre, you see:-) Spelling might suffer:-)
Regards, Tommy:-)
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Post by dave1800 on Nov 13, 2011 10:12:57 GMT
Hi Tommy Baffling to be sure. It does sound as though your problem is probably fuelling. If the float and lid is fine on the ther crab (and you have double checked there is now no dirt now blocking the needle valve) then it must be down to fuel pump pressure. Check the thickness of the insualator block and the 2 washers on this engine and the one that runs fine; check the length of the pushrods and check how far they extend (ie the throw) when they are on the cam. This is absolutely critical to having the right pressure. My compression tester has a fuel pump pressure tester built in, it is the only reliable way of checking. But if you are certain your new pump is NOS then it should be OK as long as the insulator block and push rod are correct. If you still have problems, try your SU electric fuel pump (as long as it is an original). MGB owners have found some replacement electric pumps develop too much pressure and flood the float chamber. Did you manage to get a Colourtune - this would show up as the blue flame turning distinctly yellow as the misfiring started? I'll think of you while I enjoy the 30C temperatures this afternoon  regards David S Perhaps it's down to fuel again then. At least the miss I have at idle will go away for some time if I rev the engine, and engine will smooth out for some time and just before the flooding starts, the same miss is even more pronounced, finally almost stalling the engine as petrol starts to overflow. The float is from the other crab, which runs fine.. I swapped float lids and float between the two, and the other one runs fine with the one I had in the troublesome too.. I'm trying out the third petrol pump now, which is a correct NOS SU pump. I have not checked pressure lately, but occasionally when I disconnect the fuel feed pipe at carb, petrol really blows all over out from the pipe as from exessive pressure. I have the correct insulator block between engine block and pump. Perhaps additional washers could make sense? Regards, Tommy:-) |
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Post by Keef on Nov 13, 2011 14:04:40 GMT
it should be OK as long as the insulator block and push rod are correct. Is this the unknown/Princess engine/block. Does the Princess have a different profile on the cam fuel pump lobe? |
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Post by dave1800 on Nov 14, 2011 0:22:16 GMT
On reflection, as the car has been running reasonably well, I think it is most likely dirt/rust getting through to the carb float needle valve
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Post by tommydp on Nov 15, 2011 18:18:19 GMT
Hi all!
I have not checked the fuel pressure yet, but will. My vacuum gauge can check this too, so will try plugging it to the pipe that goes to the float when running. It flooded yesterday too, can't believe there's any dirt or rust in the system. Before it starts to flood, the miss gets gradually worse until it floods and stalls. I don't believe the fuel pump lobes are different, anyway the cam is a mk 2.
Took it for a ride now and it did not flood, but the miss at idle is still present. at one try the lifting pin suggests mixture is too lean, the next it is too rich.. more or less as it's been all the time. Perhaps the pressure plays up the mixture. I also believe the exhaus smells more than you would expect. I also believe the exhaust has more white smoke/ condensation at idle than the other crab. It goes away when I drive off, and temperatures are around 0 degress celsius here now of course, so not that critical perhaps..
Regarding the radiator, I am too a bit concerned about this and coolant circulation. The upper part is very hot and lower part quite cool, also when driving. On the good crab the coolant is drawn a bit back down the radiator as I rev the engine, then coming back up again as it returns to idle. This effect is not that noticable on the troubled car and at idle it seems the coolant is rather stirred up at the radiator filling neck some coolant being forced up the filler neck. As I rev it this goes away, but the level doesn't retract as much as on the other car. It never seems to overheat though so perhaps not a problem. I have flushed it several times, but there could perhaps be a blockage though?
It seems it will take the winter too, to make this car work.. or will I be stranded forever with it? I'm totally lost.. Well, will check the fuel pressure first, just can't give up:-)
Regards, Tommy.
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Post by dave1800 on Nov 16, 2011 6:38:43 GMT
Flooding and mixture varying Has to be Dirt preventing needle valve from closing fully Too much fuel pressure Carb piston sticking, not centred or needle bent Radiator very hot top, too cool below: Primary causes Insufficient flow due to blockage in radiator or engine water pump wrong type or impeller failing Did you flush the block through the drain plug after the engine was rebuilt? There are several types of water pump; I don't know whether they have the same specs, I would guess they do but?? Any other ideas? Regards David Hi all! I have not checked the fuel pressure yet, but will. My vacuum gauge can check this too, so will try plugging it to the pipe that goes to the float when running. It flooded yesterday too, can't believe there's any dirt or rust in the system. Before it starts to flood, the miss gets gradually worse until it floods and stalls. I don't believe the fuel pump lobes are different, anyway the cam is a mk 2. Took it for a ride now and it did not flood, but the miss at idle is still present. at one try the lifting pin suggests mixture is too lean, the next it is too rich.. more or less as it's been all the time. Perhaps the pressure plays up the mixture. I also believe the exhaus smells more than you would expect. I also believe the exhaust has more white smoke/ condensation at idle than the other crab. It goes away when I drive off, and temperatures are around 0 degress celsius here now of course, so not that critical perhaps.. Regarding the radiator, I am too a bit concerned about this and coolant circulation. The upper part is very hot and lower part quite cool, also when driving. On the good crab the coolant is drawn a bit back down the radiator as I rev the engine, then coming back up again as it returns to idle. This effect is not that noticable on the troubled car and at idle it seems the coolant is rather stirred up at the radiator filling neck some coolant being forced up the filler neck. As I rev it this goes away, but the level doesn't retract as much as on the other car. It never seems to overheat though so perhaps not a problem. I have flushed it several times, but there could perhaps be a blockage though? It seems it will take the winter too, to make this car work.. or will I be stranded forever with it? I'm totally lost.. Well, will check the fuel pressure first, just can't give up:-) Regards, Tommy. |
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Post by tommydp on Nov 20, 2011 10:51:28 GMT
Hi again! I've had a look at fuel pressure now, and it seems to high, according to specs as well as the good crab.
I don't have a T- piece, so plugged the fuel pressure gauge into the petrol pipe going to the float lid, and checked pressure while car was idling on the fuel in the float chamber. The pressure is 6 PSI, which is twice the value of the specs for a 700 pump, as far as I understand. I seem to recall reading that a pressure above 4 PSI will cause trouble.
I checked the other one, which was a bit above 4. That is a Princess engine and I believe the 800 pumps on those have a bit higher pressure than the mk 2 crabs.
I suppose this can explain the stumble at idle, but have no idea what causes it. I use the correct insulator block and pushrod. Sadly I don't have a SU electric pump at present.
Tommy
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Post by dave1800 on Nov 20, 2011 11:31:17 GMT
Hi Tommy The options are to fit a fuel pressure regulator in line between the pump and carb, or you could pack out the fuel pump with additional gaskets to reduce the throw of the pushrod until the pressure falls to around 3.5psi. The MGB forums suggest anything above that can overcome the float chamber valve. I assume the higher pressure for the Princess engine was to match a HIF carb with a different float arrangement? Now all you need to do is find a reason for the hot coil. I'm totally lost on that one!! regards David Hi again! I've had a look at fuel pressure now, and it seems to high, according to specs as well as the good crab. I don't have a T- piece, so plugged the fuel pressure gauge into the petrol pipe going to the float lid, and checked pressure while car was idling on the fuel in the float chamber. The pressure is 6 PSI, which is twice the value of the specs for a 700 pump, as far as I understand. I seem to recall reading that a pressure above 4 PSI will cause trouble. I checked the other one, which was a bit above 4. That is a Princess engine and I believe the 800 pumps on those have a bit higher pressure than the mk 2 crabs. I suppose this can explain the stumble at idle, but have no idea what causes it. I use the correct insulator block and pushrod. Sadly I don't have a SU electric pump at present. Tommy |
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