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1971 MGB GT - Engine now running good - see page 8


Peter C

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Get a welder setup first and start practicing outside in the garden by running beads on old metal. The run beads between two pieces of old metal to join them up. A solid weekend of faffing around will get you enough practice. 

Remember on car bodywork it's mostly about laying tacks. This is easy than beads and often you can't get a bead in as it'll blow holes or warp the metal to fuck. 

Once you've got the knack, you'll wonder what all the fuss everyone makes about welding is. MIG welding is easy. It's ARC and TIG processes that really requires skills. 

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Have a nice time in France, the ‘B looks pretty good for the price.

Reading what you had earlier said about number plates, if you do decide to keep white & yellows I’d go for period correct and not pressed metal nor acrylic.

https://www.pressednumberplates.co.uk/products/raised-riveted-white-yellow-number-plates
 

I had a set made for my second Scimitar aged ago when they were around £80/set. Pricey but they really would look the part. 

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I've always considered the MGB to be partly monocoque and partially chassis, a sort of half way house from the MGA.

Maybe that's bollocks but having survived a number of accidents in mine, a roadster so lacking the strength a roof would add, that's my opinion.

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3 hours ago, Peter C said:

My mind works in mysterious ways and all this talk about welding the B has really stressed me out, which is particularly unfortunate as I am away on what is supposed to be a R&R holiday.

I wouldn't stress about it.

Even if you do decided to go the whole hog with learning to weld there is no time limit, you'd still have a usable car in the interim. Frankly, a few holes here and there isn't going to meaningfully change the strength of the the shell. By the time my Acclaim failed it's MOT and we started hacking away it basically had no rear strut towers, sills or chassis rails and yet it'd failed to launch a suspension component into low Earth orbit or bend in half during the many thousands of miles of hard use I'd put it through.

@blackboilersuit and I were talking about this the other day, in that anybody who's had an old banger to drive around a field will know just how much structure you can remove from a car before it actually fails...

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Back from my hols, was hoping to wake the B series from its short slumber. Nothing, battery completely dead. It's on charge as I write.

102.jpg.a6e32a4410b510ecbc335ce0f39af724.jpg

I left the tailgate open whilst I was away. There is a switch on the tailgate but I can't see any internal lights that the switch could have triggered.

103.jpg.3cfc6d5a9a4486f9ad804d379a2af597.jpg

Before I went away, with the engine running, the ignition light was on. I suspect there may be an electrical issue somewhere, which I shall add to my list of fixes.

 

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13 minutes ago, Peter C said:

Back from my hols, was hoping to wake the B series from its short slumber. Nothing, battery completely dead. It's on charge as I write.

102.jpg.a6e32a4410b510ecbc335ce0f39af724.jpg

I left the tailgate open whilst I was away. There is a switch on the tailgate but I can't see any internal lights that the switch could have triggered.

103.jpg.3cfc6d5a9a4486f9ad804d379a2af597.jpg

Before I went away, with the engine running, the ignition light was on. I suspect there may be an electrical issue somewhere, which I shall add to my list of fixes.

 

Alarm ?

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18 minutes ago, Peter C said:

There is a switch on the tailgate but I can't see any internal lights that the switch could have triggered.

The light iirc in the middle on the ceiling right at the back.

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58 minutes ago, SiC said:

Well it would have been when it left the factory 🤣

The stained marked bit in the middle is where it should be.

Stained? How dare you. That's a shadow. 

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58 minutes ago, plasticvandan said:

Pretty sure purple and black was interior light colours,it maybe that it is connected to the main courtesy light?

I checked the dashboard mounted lights (x2) and both stayed off when I left the tailgate open. 

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First of all I'd tape the switch shut and see if the problem recurs.

If it does the main fuse box is easily accessible and there's also very few in line fuses as standard. I virtually rewired mine as I'd added so many accessories over the decades; it was a pain but necessary. The cigarette lighter socket still doesn't work when the engine is running which is a bit annoying but I'm not going to try and fix it again and possibly screw something else up.

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With a bit of help from my battery charger, the engine started ok.

A quick look at the engine bay revealed a distributor that is free to move around - the locking nut is missing. I suspect the high idle and popping back via the carbs is due to very incorrect ignition timing. I don't have time to fiddle now, some of us work for living. Hopefully more on Saturday. 

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Once I sorted the Sapphire's rear light, I pulled the MGB out of the garage for a little tinker.

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I've gone through my collection of tools and these are the only imperial sized spanners that I have. I have a decent socket set with imperial bits, which should do for now.

105.JPG.d841c58bbbcd3f4db820128385273071.JPG

By fiddling with the ignition timing (I don't have a timing gun) and pushing back on the choke and throttle mechanisms, I got the idle speed down to around 1,000 revs.

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I was hoping to find electronic ignition under the distributor cap but no, the original points and condenser are still fitted. Bugger.

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The engine spits back through the carbs as soon as I touch the throttle. I'm not sure what's going on.

In other news, the DVLA have received my application for the logbook. Hopefully I will get the new logbook and find out which keeper I am before my next holiday, which is two weeks today. I don't want to invest any money in the MGB until I know that it's mine.

108.JPG.d2802af47b2e5eeaa58441fc7fcc06ef.JPG

 

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  • Peter C changed the title to 1971 MGB GT - Engine not running right - WHY? - see page 7

Rotor arms and condensers are notorious on these.  Sic is the man to ask.

But you need to time it first. Which is the 'locking nut missing' you speak of? I can see the dizzy  clamp is bolted to the engine, and the clamp bolt and nut is there.

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Deffo set your timing. You do need a timing light though really. You can sort of do it without one and eventually get it about right but you’ll never get it perfect without. They’re not expensive and it’s dead easy to do once you learn the basics (if you don’t know already!?).

In the meantime find out where all the timing marks are and go around cleaning them as they’re almost certainly covered in grime etc, once they’re clean get some tipex or white paint on a fine brush and mark them so they can be read and seen easily. There’ll be a fixed mark or pointer somewhere on the engine block and then a series of marks on the bottom pulley, that’s what you’re looking for. 
Then you need to find in a manual or online what the settings should be. All that will make sense when you get a timing light hooked up and you can see what you’re doing by adjusting the dizzy. It’s quite clear and interesting when you start doing it!

If your getting popping and farting out of the carb then your timing is almost certainly out, as it means your sending a spark to your plugs when the valves and pistons aren’t in the right places. 
  
One thing I would suggest, is try to focus on one thing at a time here as you don’t want to start pulling this that and everything apart, interfering with it and then introducing shit loads of additional variables and problems when you then start trying to adjust something else. 
If your points and condenser are currently working leave them alone for now. Although making sure the points gap is the right size is probably a good start. Once that’s set leave the points etc as they are and then time the engine with a light. At least then you know it’s set and working.

If you want to add electronic ignition then do this after you get the engine running as well as possible on the points. 
Swapping over to electronic is pretty simple, but you most likely will need to re-adjust or at least check the timing with a light again after swapping to electronic.

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Oooh.... BL tuning 😶‍🌫️

50 YEARS ago... Yupp... this pimply yoof bought a 'Dwell meter' 😯.

*All the oily rags in PC Mag advised 'edge of a match box' to set points = naah problem.

Still got it!

🚙💨

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1 minute ago, tooSavvy said:

50 YEARS ago... Yupp... this pimply yoof bought a 'Dwell meter'

I had one as well, fuck know where it is now though. Wasn't quite 50 years ago for me...

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Agree with what’s said above.  Set the points first with a feeler gauge, then set the timing.  You can check the points gap with a dwell meter, but feeler gauges will get you close enough.

Worth having a good look at the surfaces of the points that the spark jumps across, if they’re old there can be a pip on one side and a hole on the other, which makes setting them with a feeler gauge almost impossible.

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13 minutes ago, garethj said:

Worth having a good look at the surfaces of the points that the spark jumps across, if they’re old there can be a pip on one side and a hole on the other, which makes setting them with a feeler gauge almost impossible.

In my teens I got a Draper points file for eliminating such pips. Still use it today for other things, am amazed it hasn't worn smooth after 40+ years 

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40 minutes ago, Peter C said:

This looks useful:

http://www.mgb-stuff.org.uk/tm.htm
 

IMG_1725.jpeg.295cc490d055f793f6c1dfe3885830f4.jpeg

That’s exactly what you’re looking for! 
Give it a clean off and paint the marks with something brightly coloured as you’re going to need to see them easily standing from above the engine while it’s running! Once the timing light is hooked up and working you’ll see them, then as you very gently twist the distributor one way or the other you’ll see all the marks start to move. If you’re twisting the distributor the wrong way the marks will drift away from the fixed mark and the engine starts running like crap! Go the other way and you’ll see the marks start aligning and the running should improve. 
Your basically looking to get the 8 degree or 10 degree before top dead centre mark (depending on your engine type) to line up with the line mark on the pulley.

You might need to ever so slightly fine tune this by ear/feel afterwards depending what fuel your running, as sometimes modern petrol can cause slight differences. 
When I did my Capri recently I timed it up to what the manual said and it’s perfect though - so you might be fine at the book setting.

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