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Post by tommydp on Nov 26, 2012 20:09:29 GMT
Hi all! I'm all well and still with you, but haven't been very active lately. Sorry!
First of all, it's been very cold here and as I don't have any heated place to work on the cars I haven't done much Landcrab related stuff..
Next, I've lost some interest as the blue one continues to show no end of random running issues for no obvious reasons.. Rather frustrating, with a fortune spent on it with the reconditioned engine, new carb, new distributor and so on and so on... As a result I've laid it up and delivered the license plates to the authorities. I just can't sell it and will start from scratch and get to the bottom of it one day. Be prepared for new, lengthy threads some day! I'm pretty sure there is still a timing issue, and have found similiar problems om the net regarding MGBs and crap Rolon timing chains, sprockets and tensioners which give "changing valve settings, fluctuating timing marks" etc.. which sounds familiar..
Anyway, it will rest in the barn for a long time..
In the meantime I have however started looking at the white one and this one has got my motivation back:-) It seems it only needs some work to the brakes to get back on the road, so my plan is to have this one finished by spring. Ironically, I now prefer this 180 000 kms, £200 unrestored car to the blue one.. It idles, runs and drives beautifully all the time and shows no sign of the strange behaviour of the other one. Far more fun working on this than scratching the head over the blue one:-)
Updates to come! Regards, Tommy
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Post by dave1800 on Nov 28, 2012 10:43:02 GMT
Hi Tommy
I sympathise with you not wanting to work on the car in the freezing cold; I still have the opposite problem here it is +33C too hot to do much outside - and it's supposed to be winter and around 22C this time of year.
As far as the varying timing is concerned I have also read about timing chain problems. I do recall when I rebuilt a MK111 engine as a MK11 that I used the old duplex timing chain and sprockets that had already completed 150K miles as my funds were running low. I was determined to change them later but never did and they completed the next 100K+ miles without a problem. The wear on duplex chains and sprockets seems to be negligible compared with simplex arrangements under normal road conditions.
When it is warmer you could check the timing chain, tensioner and sprockets against those on the white car to see if there is any obvious difference and compare the valve timing again. The (ignition) timing could be jumping if there is wear in the distributor bearing or the sensor wheel (electronic) isn't perfect etc as well as the chain drive to the camshaft. The better magnetic (hall effect) sensors use a vane arrangement that doesn't rely on an accurate gap between the sensor and shaft to determine the trigger point. Something to ponder until Spring!
regards
David
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Post by Penguin45 on Nov 28, 2012 18:36:00 GMT
I sympathise, Tommy. I've spent far too long rolling about under cars in winter. Mind you, the garage is quite easy to heat now........ ;D Snow forecast for Yorkshire from next Monday.  Chris. |
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Post by tommydp on Nov 28, 2012 22:49:48 GMT
Thanks! I will rebuild the brakes of the white one during the winter no matter what! I have a propane heater, which makes working in the barn a bit more pleasant. Really looking forward to putting it through the MOT. Apart from the brakes I think it only needs a rear exhaust section and ideally a set of engine mountings. What's your experience with the modified LOCI item, Chris?
I believe its engine is very good. The previous owner serviced it very well from he bought it new in 1970 until it was put into storage in 1988. The oil and filter was changed every 5000 km during all these years, without exception! Even more frequent in periods, typically around holidays when it towed a caravan. I have a log book where everything done to the car is documented, with date and mileage.
Engine/ cam/ timing research on the blue one will have to wait for sure! Before I put it away an "old school" car enthusiast had a look at it. He offered me some old spares and as he came to deliver them I challenged him to diagnose it. He found nothing obvious, but at least he agreed distributor (the new rebuilt one with points), the coil, HT leads, plugs, carburettor, overheating issues and air leaks could be ruled out.
After idling for a while, he confirmed oil gets into the cylinders especially 2, 3 and 4. At least by the time we had it idling, the plugs did not get fouled though. As the engine is rebuilt and showed excellent leak down test he agreed the valve guides had to be the way the oil enters. He had a look at a before mentioned head I have on the bench, the one I had on the car earlier with the same symptoms. He could confirm the valve guides/ valves on this were extremely worn, and tuning the engine with such worn guides would be impossible.. I'm not sure if the present head is much better...
He claimed however, the oil would not cause the random miss and stumbling. The other thing which caught his attention was the coil temperature.... It gets abnormally hot after idling for say 10 minutes, all coils I've tried does this remember? he was not sure what causes this, as obviously every single ignition component is spot on and substituted numerous times.
He found it hard to believe the timing could be wrong, if there was a serious problem here it wouldn't have run as well as it actually does according to him. He agreed however, that as the engine heated up it developed a random miss and stumble. Listening to the exhaust and comparing to the white, he agreed the blue one did not have the excellent rhytmical, steady sound as the white. He believed it's caused by a valve issue, possibly a timing chain, tensioner issue..
He would discuss it with others, among them a former BL mechanic he knows:-)
My plan is therefore, some time in the future:
- Take the head off, have Burgess rebuild a head
- Get a high quality sprocket and timing chain set
- Have the mentioned bloke, or another skilled cam timer, helping me dial the tdc/ cam/ valve to see if the cam is good, if not fit an excellent, original standard MGB cam which I've now got hold of.
- Put it all together, set timing and carb once again
- Hope for the best and turn the key...
But before that the white one is going back on the road permanently:-)
Regards, Tommy
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Post by dave1800 on Nov 29, 2012 11:25:01 GMT
Tommy A quick and easy test on the coil. Insert an ammeter - not an electronic one - in series with the positive coil feed from the ignition switch and the + coil terminal. Measure the current with the CB closed and the engine not running - record the reading (about 3-3.5 amps). Start the engine with the ammeter still in place and take the average reading at idle. Now repeat on the other car and compare the readings. Also take note of the battery voltages with the engines at idle. (If you use an elecronic multimeter the back emf from the coil may damage it). If the readings are the same then both coils should heat up similarly. If this is not the case you may have discovered a way to break the laws of physics! It would be interesting to see your findings and see if we can explain this baffling phenomenon. Regards David The other thing which caught his attention was the coil temperature.... It gets abnormally hot after idling for say 10 minutes, all coils I've tried does this remember? he was not sure what causes this, as obviously every single ignition component is spot on and substituted numerous times. Regards, Tommy |
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