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Post by dave1800 on Jan 4, 2011 11:40:35 GMT
Did you check that the replacement rotor arm is identical to the one that failed and is definitely the right pattern? You can check that the rotor arm contact is opposite the distributor cap terminal throughout the WHOLE range of advance. As your problems seem to occur close to the rpm and driving conditions when the mechanical advance and the vacuum advance are at a maximum, if the rotor arm contact is too far from the distributor cap terminal this could cause a mis-fire especially if the coil is weak. I assume when you reassembled the engine you aligned the distributor position correctly? I've read through this a couple of time now and the randomness of the problem is worrying. With due respect to the above posters, I think I'd be looking seriously at the ignition. There are well documented problems with current Lucas components all over the internet, relating specifically to distributor caps and rotor arms. The DISTRIBUTOR DOCTOR has components which work and are not particularly expensive. My own car got through several black rotor arms in short order before fitting one of his red ones. No problems since - probably because there's a spare one in the door pocket.  You could try the "In the dark" test - easy at this time of year. Get the car properly warmed up, then lift the bonnet in the dark. If the ignition circuit is breaking down in any way, you will see random sparks or even rather pretty electrical tracks along the leads. You will need to rev the engine quite hard to see any effects. Chris. |
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Post by kelsham on Jan 4, 2011 16:22:00 GMT
Hi, all thanks for the suggestions, I had not realised the oil separator was built into the back of the cover.
I am going for the carb change because the fault appears to relate to the throttle being opened. The car drives OK at lower speeds.
I have tried three rotor arms.
She ticks over nicely and drives well. The only item I havent changed is the dissy cap, it has no obvious marks and is fairly new.
Its a bit cold out and thankfully I am still awaiting the new needle and jet.
I have already changed them on the later carb and can confirm I centralised it. It dropped with a satisfying click.
One more detail I forgot to mention. the carb kept loosening the damper and unscrewing it from the dashpot.
I finally lost it while testing the car. One difference in the Mk 1 and later carb is the angle, It is neccessary to alter the float chamber mounting.Thanks for your interest.
Regards Kels
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Post by tommydp on Jan 4, 2011 18:47:03 GMT
We're getting closer:-)
I must admit, that I now agree with the latest posts here and suggest a closer look at the ignition. If idle is smooth and even, without misfire, it's more likely that the problems you're having are due to ignition fault rather than than air leaks, in my opinion. But of course, I could be wrong. My bet is mechanical or vacuum advance related problems. Perhaps due to maladjustment.
Have a look at ignition related tips in previous posts, both by others and myself. The trouble reminds me very much of the headaches I had when putting my current 1800 engine together. Finally, a (very) old mechanic suggested I had a look at the base settings, as everything had been dismantled and out of tune.
For example, how are the settings of the carb and distributor acting together. It will run in many different settings, but it could be hard to find the exact points correct for the whole range, considering rpm, load, speed. Perhaps the throttle is too much open while the distributor is too much retarded (anti clockwise), then you could have too much vacuum advance applied at idle, giving less vacuum advance at speed.
I would set the ignition static, around 10 degrees btdc, start it and tune idle and mixture from this. Lift carb piston to listen for correct tuning at idle. Should rise and then fall down.
Also remove plugs, turn engine to TDC on the fire stroke for cylinder one (valves on this cylinder closed) Where's the rotorarm pointing? Away from cyl 1 segment on distributor cap?
Best of luck!
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Post by tommydp on Jan 4, 2011 20:18:05 GMT
Another tip from frozen Norway:
Check ignition advance operation,
Mechanical advance: remove dizzy cap, grab rotor arm and turn fully anti- clockwise. Release arm and it should return to original position.
Vacuum advance: grab dizzy baseplate, holding points and condenser gently. Turn the plate fully clockwise, in this position block the outlet pipe on top of the vacuum unit of the distributor with a finger. Relase the baseplate, still blocking the pipe. The baseplate shall remain in position, if it works and holds vacuum. Once you remove your finger from the pipe, it should return to original position.
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Post by kelsham on Jan 10, 2011 13:26:00 GMT
Well some progress made I have fitted the Mk1 carb and manifold. I am not ignoring the help offered by you all, Vac advance had already been checked.
I intend to reset the ignition timing as over a period of time it has been altered several times.
In the familiar 1 step forwards 1 step back scenario I seem to inhabit I discovered the Mk 3 exhaust pipe is showing signs of imminent failure. very rusty.
I have a replacement to hand. Does anyone know where I can source a lower exhaust mounting for this pipe? I have a home made bodge on at present. It seems like a good time to replace it.
Regards Kels.
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Post by kelsham on Jan 16, 2011 14:10:30 GMT
Well I decided to replace the exhaust pipe earlier today. Much cursing and swearing went on. Finally managed to get the lower clamp to fit and hold the front pipe at a reasonable angle.
When I went to start the car she fired up straight away. Sadly she ran at high revs. I need to go back and reset the tickover etc.
Can anyone with a Mk1 manifold tell me where the top of the throttle return spring attaches. I cant remember and it does not look right where I have clipped at present?
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Post by dave1800 on Jan 17, 2011 10:20:35 GMT
I find that it helps to take the weight of the exahaust by putting a jack with a block of wood under the front pipe where it bends up so that the flanges align. It makes fitting the clamp so much easier. Do you have a BMC/BL workshop manual, if not they are often on EBAY and will show you how the spring fits. I'm not at home for a while or I could copy the section for you. I suggest you manually close the throttle fully to see why the tickover is so high and make sure nothing is stopping the butterfly from closing - changing the manifold and carb shouldn't have resulted in much if any change of idle. Well I decided to replace the exhaust pipe earlier today. Much cursing and swearing went on. Finally managed to get the lower clamp to fit and hold the front pipe at a reasonable angle. When I went to start the car she fired up straight away. Sadly she ran at high revs. I need to go back and reset the tickover etc. Can anyone with a Mk1 manifold tell me where the top of the throttle return spring attaches. I cant remember and it does not look right where I have clipped at present? |
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Post by kelsham on Jan 17, 2011 13:08:42 GMT
Dave, I used a trolley jack to adjust the front pipe. The problem was due to the Mk3 exhaust fitted, it does not match the original exhaust bracket on the gearbox. I had to make up spacers.
I have a pile of workshop manuals, although they show the carburretor and bracket, none show the spring.
You have to bear in mind that the carb I fitted has been floating around various garages for the last ten years. I have probably borrowed parts from it in the past.
I rebuilt it with a new jet and needle and need to readjust the settings. I usually use a colortune.
Back to my request for help. If anyone with a car fitted with the early progessive throttle could check where the spring attaches it would be a great help.
Regards Kels.
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Post by Keef on Jan 17, 2011 17:09:10 GMT
car fitted with the early progessive throttle could check where the spring attaches Amy use? :  |
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Post by ahctog1 on Jan 17, 2011 20:31:10 GMT
Avoid rotors with a rivet, they cause all sorts of problems.... as Chris says... get a red one.
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Post by dave1800 on Jan 18, 2011 2:34:35 GMT
Yes you will need to ensure the float chamber is still horizontal as the angle to carb fits to the MK1 manifold is different.
Still wondering aout your ignition, if you have tried 3 rotor arms you are either unlucky or the ignition is under stress or weak. Refer to my earlier post, is it possible the distributor drive has become misaligned or there is voltage loss in the coil primary circuit - bad connection etc?
regards
David
[quote author=kelsham board=talk thread=53 post=333
I have tried three rotor arms.
One difference in the Mk 1 and later carb is the angle, It is neccessary to alter the float chamber mounting.Thanks for your interest.
Regards Kels[/quote]
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Post by kelsham on Jan 18, 2011 16:46:52 GMT
Hi all, the picture shown on the right hand side is the type of throttle control I have. Maybe I am going crazy but I cant see where the spring attaches?
I am aware of the different angles of the float chambers, I have the correct angle.
I had a rotor arm short down, replaced it with one off ebay, then when I had poor running changed it for another one off Ebay.
Finally thought I would use an old one I had from the old distributor. All seemed to work. Various adjustments left the polite cough at higher speeds.
Come on someone take a look at their car and tell me where the spring goes?
Distributor drive has been altered one tooth and is correct, connections resoldered.
Thanks for your interest, will get back to it tommorow and set mixture and check timing.
Regards Kels.
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Post by kelsham on Jan 23, 2011 16:06:52 GMT
Hi all,
well I fitted the Mk1 carb and manifold, When I took the car for a test drive I found that once warm the idle kept going high.
I tried fitting the return spring in various positions without success.
Finally patience exhausted I removed the carb and fitted the later operating mechanism to it.
Then I had the problem of broken connector to the choke cable. I found a good one but it was oversize. I fitted it into my electric drill and with a file reduced the diameter to fit.
I could have drilled out the carb mechanism, but decided to keep it standard.
By this time the Mid Wales weather was winning and I went indoors for a bath and warm up.
I will try another roadtest soon.
Regards Kels.
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Post by kelsham on Jan 28, 2011 15:37:54 GMT
Well the connector nipple I modified broke as I tried to tighten it. I obtained one for a mini.
First try the car was smoking badly when the throttle was blipped. I suspected the fume control valve on the manifold.
I dismantled it and it was full of oil. Apparently the later oil separator is not compatible with the early fume system.
I removed the valve and blocked the hose. Refitted the old carb, required because of the different position of the fume connection.The early carb is missing this vital part.
Tried the car out today. Runs ok at lower speeds, due to the local roads, higher speeds not possible. I will have to drive over to Welshpool next week there are some long straight roads over there.
I decided because of the urging I had received on here to recheck the compression readings.
Two at 170 One at 160 and one at 150. I tried them several times. Hot and cold.
They varied and the gauge which I bought in the early 1960s kept jamming open. So inconclusive but No 2 cyl was always lower than the others.
Probably the result of running weak, I am hoping its the valves. I intend to run the car and retest after a few miles. No more smoke and she seems to be running well, that is apart from the temperature transmitter which went intermittent and caused the needle to drop.
Regards Kels.
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Post by dave1800 on Jan 29, 2011 4:35:45 GMT
Hopefully the compression test isn't anything to worry about I've seen that level of variation and lived with it for tens of thousands of miles as there were no obvious problems such as oil in the water or having to top up the water or loss of power, but finally cured by a head gasket change. It was blowing between the cylinders but showing up more on one than the other on the compression test for reasons I could never comprehend. I also rebuilt a Mk11 engine that had done 110,000 miles. It ran very sweetly absolutely no misfires and would still go off the end of the speedometer but consumed excessive oil - 100 miles a pint if driven really hard but much less driving normally. When I took it apart there wasn't a single piston ring that was complete! But it didn't misfire.I hope your misfires are a thing of the past. What I'm trying to say is that the engine is incredibly tolerant; if a burned valve was giving a lower compression reading it would show up more at low rpm. It does sound as though it's possible the oil collecting in the breather valve may have been drawn in at higher speeds under light load when the strain on the ignition is at its highest and caused a temporary misfire. Do keep us informed, it's a bit like a mystery play we need to know the ending! regards David Well the connector nipple I modified broke as I tried to tighten it. I obtained one for a mini. First try the car was smoking badly when the throttle was blipped. I suspected the fume control valve on the manifold. I dismantled it and it was full of oil. Apparently the later oil separator is not compatible with the early fume system. I removed the valve and blocked the hose. Refitted the old carb, required because of the different position of the fume connection.The early carb is missing this vital part. Tried the car out today. Runs ok at lower speeds, due to the local roads, higher speeds not possible. I will have to drive over to Welshpool next week there are some long straight roads over there. I decided because of the urging I had received on here to recheck the compression readings. Two at 170 One at 160 and one at 150. I tried them several times. Hot and cold. They varied and the gauge which I bought in the early 1960s kept jamming open. So inconclusive but No 2 cyl was always lower than the others. Probably the result of running weak, I am hoping its the valves. I intend to run the car and retest after a few miles. No more smoke and she seems to be running well, that is apart from the temperature transmitter which went intermittent and caused the needle to drop. Regards Kels. |
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I've read through this a couple of time now and the randomness of the problem is worrying. With due respect to the above posters, I think I'd be looking seriously at the ignition.
