1973 MGB GT- A little rust 30/08

[ChasR]

Aha, I forgot that your car had a 45D4 dizzy (IIRC these were meant to come with a 25D4 (which come with a knurled adjuster on the distributor to allow for quick ignition timing changes). As with anything, this can change over time .

But the cap should not be loose fitting at all. Even with the clips off, the cap should locate on well and not move about if it is held onto the distributor .

Keep at it, it should become a reliable car once more .

[adam73bgt]

Yeah I think the distributor should be a 25d4 too, though at one point I thought it had the wrong carbs on it It's not the original engine anyway so who knows whats in it haha

Ah right, well I've ordered a new cap so hopefully it'll fit a bit better than this one, as the current one is really quite bad..

I do hope it becomes reliable again as on the whole its been pretty good really, I suppose one can forgive a 40 year old car for having the occasional breakdown and even then, it seems to be the less than a year old parts letting it down so I can't even blame it on the car's age haha

[ChasR]

Welcome to the world of curse word quality parts on cars . Rubber bushes are a favourite of mine (I have seen inner arms bushes on those fail within a couple of years and barely any miles) in addition to ignition bits. Most classics are the same (Beetles, Stags, you name it).

It seems you do get what you pay for, but paying for the right items can muddy the water somewhat.

[adam73bgt]

Well I've been trying to boost my mojo with the B by getting some form of wipers working.

For the last month or so, I've been going round with one wiper as the motor had appeared to become unable to turn both wipers at the same time due to the level of friction involved.

So I got on with stripping the mechanism out of the car and after a bit of motor stripping down, I was left with something like this



All the parts inside seemed to be in relatively good condition compared to the replacement motor I had bought but I've decided to go ahead and strip the replacement motor down and regrease it.

So after a fair bit of a faff and lots of grease (hence the lack of photos, it got quite messy..) I had something like this



Then it was a relatively simple case of adding further grease to the cable/rack and the wheelboxes and metal tubing over the rack





Got the fiddly job of feeding it all back into place now and fixing it with my new motor fitting kit, also going to need to get some rubber tubing or something to fashion up another of these wheelbox spacing doodahs as one of the car's has gone missing at some point in its life..



Other jobs include fitting the new ignition system parts once they arrive so I can actually get the car usable again, plus I need to find a way of freeing the rear section off the exhaust so I can get my new back box on, oh and refurbing wheels whenever I find the time..

I suppose things are starting to look up again with the MG

[adam73bgt]

Well this has been a bit of a rollercoaster ride recently..

The new ignition parts arrived, nicely fitting rotor arm stuck in place of my slightly butchered temporary one, new better fitting rotor cap whacked on, new GREEN HT leads (easy extra 20hp right there), new triple electrode spark plugs (nother 20hp there again)

And it ran!




For about 15 seconds, then it became a 3 cylinder.. then I turned it off.

Swapped out the plugs for the old NGK's as I knew they worked, cylinder no.1 plug was wet so not firing. Went to start again and car did nothing, turning to ignition killed all the electrics in the car. I could see/hear the interior light and clock stop and start working again as I turned the key to ignition and back

A bit of head scratching and some advice on here led to me checking for an earth issue (as 90% of my electrical issues seem to be) The engine earth strap was looking like this



Not pretty. I had bought a new strap ages ago and had planned to fit it, but the nuts were pretty solid. Managed to free one off with plenty of penetrant (ahem) though, the other end wouldn't come undone as the stud which the nut is fixed to decided to spin too

Now sorted with new earth strap



And thankfully the car quickly fired up and idled happily. Which surprised me as the car had been taking quite a long time of spinning on the starter to start recently, but this was a quick start and from cold too!

So hopefully thats my running issues sorted (touch wood)

Now just to get the wipers back in and I might be able to drive to work tomorrow haha

[Mike]

Have you fixed the wiper motor problem. Looks like the problem is in the kink in the metal tube to me. Looks like its bent prity sharp i know they don't like much bending from personal experience!

[adam73bgt]

Nov 15, 2013 15:32:48 GMT Mike said:

Have you fixed the wiper motor problem. Looks like the problem is in the kink in the metal tube to me. Looks like its bent prity sharp i know they don't like much bending from personal experience!

You just beat me to it

After some amount of fighting and swearing and cursing, the wipers are fitted and they work!

So basically I'd cleaned out and repacked the replacement motor with plenty of grease, did the same for both wheelboxes and got plenty of grease in the metal tubes where the cable runs. Put it all together and carefully slid it back up behind the dash.

Some tips if you happen to find yourself attempting this:

• only do up the nuts loosely to begin with as the metal tubes need a big of jigging about before they're happy
• It helps to move the tube that feeds the demister on the drivers side, just pull the top end of it from under the dash and let it hang to give extra space
• Get the wheelboxes to poke through the holes in the scuttle and get the nuts on the end of them, an assistant would come in very handy here as its bloody hard to balance the wiper motor with your foot while trying to reach out and round the A pillar to hold the ends of the wheelboxes
• when mounting the motor itself, leave out the flat rubber piece at first to make getting the bolts into the bulkhead a LOT easier, once they're in loosely you can slip the rubber up and in to place
• put the electrics plug into the motor before you mount it or you will hate yourself.

After a while the whole lot was roughly in and it was just a job of tightening everything up. I still need to get a rubber spacing tube for the passenger side wheelbox but I can fit that at a later date pretty easily.

So now the wipers wipe a whole lot more effectively, the motor has no issues driving two wiper blades at a time, even across a pretty dry screen, so I'm happy

The radio also seems to have suddenly grown a memory too which may be another upshot from the new engine earth strap?..

But oddly the rev counter and fuel gauge have both stopped working since I fitted the wipers, so I think I may have knocked off a spade connector somewhere :/

[goldnrust]

Woo glad to hear this car's back working properly again It's amazing what a good earth can do. I should really go check the earths on my car….

[Rich]

The wheelbox bezels should be chrome mazac with a rubber seal underneath. You can buy a 'repair kit' compromising of 2 bezels, 2 new nuts and 2 new gaskets. Worth it.

[adam73bgt]

Nov 15, 2013 18:45:12 GMT Rich said:

The wheelbox bezels should be chrome mazac with a rubber seal underneath. You can buy a 'repair kit' compromising of 2 bezels, 2 new nuts and 2 new gaskets. Worth it.

The outer bezels are in reasonable nick (compared to most of the brightwork on the car) I do need to get a couple of the gaskets though, the bit thats actually missing is the rubber spacer that goes underneath the scuttle panel in order to give something for the wheelbox to tighten up flat against, my flatmate offered me a block of rubber (think its a bush for something) to make a new one out of but I can't be bothered so no doubt I'll end up on ebay or moss and get a kit to change the whole lot like you say

[adam73bgt]

Hmm not entirely good news.. Went for a little drive to get some fuel and found that the engine is spluttering/misfiring when you accelerate more than about half throttle or when going up a slight hill :/ grrr

Back to the drawing board...

[crahel]

What do they say about earths, 99% of auto electrical problems are earth related and the other 1% is the earth. Glad is worked out.

[jpsmit]

Nov 15, 2013 22:16:18 GMT adam73bgt said:

Hmm not entirely good news.. Went for a little drive to get some fuel and found that the engine is spluttering/misfiring when you accelerate more than about half throttle or when going up a slight hill :/ grrr

Back to the drawing board...

Didn't go back into your posts, but, if you are running SU's, it sounds very much like your dashpots are empty - couple of teaspoons of oil and you should be good to go.

[adam73bgt]

They should be filled up, but I will check them. I'll be rather annoyed if they're leaking..

[goldnrust]

Sorry to hear it's stopped running right again.

Maybe it's worth going back to basics, the engine needs air, fuel and spark to run, one will be missing! As it's a problem with wide open running you'd be looking for an air restriction, blocked air filter etc? Probably not as likely as the other options, but always good to rule it out.

Fuel next, the obvious point in fuel delivery is the carb…. I've no knowledge of SU carbs so I'll leave that to someone else! But…if you cruise on light throttle, then stamp down does it immediately start missing, or does it take a few seconds or longer? If theres a delay between opening the throttle and it starting to run rough then fuel supply sounds a likely problem. Changed the fuel filter recently? My rx7 has similar symptoms to your mg and it turned out the fuel filter was full of curse word and blocked. When I started driving hard it would drain the float chamber in the carb faster than it could re-fill. And if that's all ok, hows the fuel pump?

Finally spark! If it starts missing immediately that you work the engine hard (no delay like mentioned above) then weak spark could be likely. My Lancia had a coil start to fail, as did my motorbike, and both had similar symptoms to what you're describing. The coil was kicking out enough power to spark the plugs when I tested them and to idle etc, but once pushed hard they just weren't up to the job. If the coils good then how about connections to and from it, wires leading to points etc?

Hope you get to the bottom of this soon! Good luck!

[adam73bgt]

Nov 16, 2013 10:20:31 GMT goldnrust said:

Sorry to hear it's stopped running right again.

Maybe it's worth going back to basics, the engine needs air, fuel and spark to run, one will be missing! As it's a problem with wide open running you'd be looking for an air restriction, blocked air filter etc? Probably not as likely as the other options, but always good to rule it out.

Fuel next, the obvious point in fuel delivery is the carb…. I've no knowledge of SU carbs so I'll leave that to someone else! But…if you cruise on light throttle, then stamp down does it immediately start missing, or does it take a few seconds or longer? If theres a delay between opening the throttle and it starting to run rough then fuel supply sounds a likely problem. Changed the fuel filter recently? My rx7 has similar symptoms to your mg and it turned out the fuel filter was full of curse word and blocked. When I started driving hard it would drain the float chamber in the carb faster than it could re-fill. And if that's all ok, hows the fuel pump?

Finally spark! If it starts missing immediately that you work the engine hard (no delay like mentioned above) then weak spark could be likely. My Lancia had a coil start to fail, as did my motorbike, and both had similar symptoms to what you're describing. The coil was kicking out enough power to spark the plugs when I tested them and to idle etc, but once pushed hard they just weren't up to the job. If the coils good then how about connections to and from it, wires leading to points etc?

Hope you get to the bottom of this soon! Good luck!

The air filters look fine to me, they're the big K&N jobbies so it would take a lot of rubbish to block them up, may take them off and give them a good shake though! The fuel filter is quite new, think I replaced it not long before I went back up to uni so can't be more than a few months old, I rebuilt the carbs around that time too so most of the rubbish should have been cleared out of them then. Fuel pump isn't something I'd considered really, its a bit of an unknown quantity but it seems to keep the fuel filter plenty full of fuel while the engine is running :/

I think its likely to be a spark issue at the moment, my suspicions do aim at the coil at present as there was quite a lot of corrosion on the king lead when I removed it.. annoyingly its not that old

Hopefully I can get it sorted soon and get driving about in it as its rather knocked my confidence in the car lately

[goldnrust]

Might be worth checking the fuel filter again. When my tank was full of bits of rust, it would clog a filter up in just a few weeks.

Either way spark seems a sensible place to concentrate for now, I just mentioned the other things as it's not good to work yourself into a corner as it were, and forget the bigger picture. At least a coil is a fairly easy thing to swap out and test

[adam73bgt]

I'll keep an eye on it, though I did manage to run the car for pretty much a whole year without one at all..

Aye, I suppose it was looking away from the distributor and at the engine earth which got the thing running in the first place, so I shall keep my options open. Thankfully theres not all that much stuff under the bonnet to go wrong compared to a modern car so I'm probably lucky in that respect

[adam73bgt]

Another wordy and slightly boring update..

The car seems to be working again, I say this tentatively because I didn't really do anything particularly in depth to make it so.. Went and checked the vacuum advance by sucking on the hose, checked the mechanical advance by messing about with the rotor arm by hand, also checked over the wire inside the dizzy going to the accuspark system just to make sure it wasn't catching on anything. Fired it up, let it warm up a bit and took it for a little blast round the block and no stumbling that I could hear/feel.

Drove it to work later and all seemed well so can't complain



...

However there is a new tickety/tappety/flappy noise coming from the exhaust side of the engine on acceleration which I am thinking is possibly an exhaust gasket of some description being a bit blowy

Also the hot idle issue is still there, I've not changed the throttle cable yet which is my current main suspect but I may get the B into a garage just so I can get the whole engine checked over for my own piece of mind and so I can have a happy running car!


I'm also in two minds about possibly getting a modern daily.. which would be disappointing as I like being one of the few classic cars on the road over winter but would also give me more time to do some more interesting stuff to the B...

[Deleted]

I wonder if the hot idle could be down to vapour lock? I know that when the Princess has been on a long run I have trouble getting the engine to idle when warm because the SU carb gets far too hot. Letting it cool down, or giving it a bootful to clear out the tubes seems to do the trick but I reckon the knackered heatshield is probably the real culprit. If it were a regular problem I'd do something about it.