Loss of power / surging?

[Trickydicky]

From the posts in this thread you sound like you are getting nowhere, how can you set the mixture correctly after changing the dizzy and not being able to set the timing due to the mixture being incorrect?
Surely the best plan of attack would be to get the engine running as best you can on the old dizzy, set the mixture and then swop for electronic ignition and set the timing?
Or am I lost?

[nwxh]

I've gone from never owner a car before or knowing how to do any work on one two months ago, to fitting a new dizzy and taking out a spark plug for the first time today. (I'm hoping I'm not testing people's patience too much by my ineptitude.) Thanks to everyone on here for the help and patience.

I doubt that the timing was right in the first place, as it seems something was always wrong (condenser and/or points gap). I think I'll try again tomorrow with the colour tune (for want of a piston lifting pin), but turn up the idle screw before I use it (didn't occur to me at the time) then play with the dizzy and oscillate between.

My next step will be to get a new fuel pipe and see to the carb. I also have the suggested compression tester, but won't use it until I've got the rest sorted and gone on a drive to top up the battery since I'll use the start motor.

[nwxh]

Just remembered, as well as the old loom, there's a flat and black PVC cable housing two PVC cables, which I think is going to the key switch. Is this a legitimate automotive wiring, or is this someone's bodge using household wiring?

[bmcecosse]

Sounds like a bodge. If the lifting pin is stuck UP - you will never get the mixture/idling sorted. So get that either fixed, or confirm as 'missing' before going any further. Colour tune is a complete waste of time....back in the box. You need to do the compression tests first! To find the overall condition of the engine... Then if it's ok (150 psi or so on all cylinders) - it's a combination of swinging the dizzy gently - and adjusting the mixture slightly - to get the best idle. It's a 5 minute job!! Then a good road run to confirm not pinking - and finally a plug colour check....

[nwxh]

Thanks. Will do a compression test tomorrow. Only fear is running the battery flat!

I'll send a picture of the base of the carb. If it was stuck up, would it still appear to be working (i.e. acceleration and engine braking seem to be unaffected to someone who's never had it working)?

Why is the colour tune a waste of time? Because it appears to be accurate but is only analysing idle running?

ps spark plug was brown. I'd suspected it was running rich.

[bmcecosse]

Run the engine up to operating temperature first - that will charge the battery. Brown plug is not too bad - it must be checked after a good hard run - with no idling.......

[kennatt]

Yes comp test first now you have the tester. Remember Engine hot,all plugs out and throttle fully open(Assistant or brick on pedal).The reason a colour tune is not needed is that you have a built in one on the carb,The lifting pin,it must be there,never heard of one not being there from new,not sure if they can even be taken out,but if so there will be a small hole under the carb at the side where it should be. A thin nail or screwdriver,maybe. By the way, you are on a very rapid learning curve,and the minor is such a simple car that you will learn a great deal about the basics in a very short time. Well done for trying to sort it out. Many,very many ,owners simply shove the car into one of the so called Minor specialist garages ,pay a fortune for basic maintenance,even after guidence on here. Good on you,and keep at it you will soon become an expert and may even beat Roy (BMC) to be the first to post a reply

[nwxh]

Thanks and sorry to drag this on.

Compression test
All spark plugs out. Used starter motor with my foot on the pedal.

Cylinder 1: 60 psi
Cylinder 2: 60 psi
after which I used a spanner to screw in the compression tester head just in case (damaging the rubber seal slightly)
Cylinder 3: 55 psi
Cylinder 4: 55 psi

Lifting pin
Only photo came out ok, and sadly I only got the front of the car side of the carb jet. Is the pin meant to go in the small circular round flat section in the top left of the photo?[frame][/frame]

Colourtune
Used for want of a working lifting pin. Tune it such that the colour oscilated between blue and orange, though it was always orange if the revs were raised. Found car would run fine at high revs but stall or surge if the engine revs were low. So I adjusted the mixture nut back until two flats from where the engine started reving more with more fuel. I assume something's up with the carb?

Garage
I had some work done a week after getting the car, however the cost was double what I expected, so I'm trying to do my own work. However, I do work on a university car park and I won't attempt MIG welding until I get my own house with a garage, so I'm going on Friday to get the bodywork assessed (wood is knackered). I'd consider doing the woodwork myself at parent's house, only if no welding is required.

I think I will see if they can assess the engine too. Especially get a compression test with a professional tester.

I don't know if I should take out the engine and work on it myself. I spoke to someone who said that back in the 60s/70s student would take engines into their kitchens, but I suspect such practices wouldn't be allowed now.

[bmcecosse]

These pressures are desperately low.... - so low I don't believe them. Can you test the tester on another car ? Are you sure it's reading psi ? And this was with hot engine and fully charged battery - and all the plugs out... ? engine spinning round at high speed ? It looks like the pin is stuck up - which won't allow the piston to settle down on the bridge - have you checked that? Take the top off (two screws) and look for the pin from above...

[nwxh]

I didn't want to believe the tool either. All plugs were out The inserts wobbled a little bit, yet any larger inserts were clearly too big. To rule out the insert being loose, I tightened it with a spanner on number three, damaging the rubber seal.

I'd run the car around, to heat up the engine. I then ran it without a fuel pump until it stalled to minimise petrol leak out of the exhaust/into the air. Can't confirm the battery fully charged in that time, but it started again after the test.

Don't know what you mean by high speed. I ran the starter motor with the accelerator all the way down.

What should I do next? Get a professional compression test on Friday? Buy a more expensive tester? Cheers!

[nwxh]

Thanks for the suggestion! Didn't realise you could simply remove the top like that, and have the dashpot oil remain. The lifting pin is missing. I can now see exactly where it should go! The piston seems to be in good condition otherwise i.e. not stuck and the dashpot is resisting. Should have saved money on the colourtune.

[bmcecosse]

If the pin is missing - and there is now a little hole - then you need to plug the hole or it will leak in air spoiling the idle... Comp test probe would need to be 'nipped up' to get a seal. The pressures you show are ridiculously low. Maybe it's a low compression van engine....even then - they are far far too low.. Try again with properly warmed up engine. Then squirt some (enough to seal the rings) engine oil in each bore and immediately test again.

[nwxh]

Thanks. Will duct tape do until Friday when I get a new pin? So is it likely that this explains why the car seemed to be running leaner when the revs went up?

How much is nipped up? The probe was tightened with a spanner enough to damage the rubber for cylinder three, yet I got 55psi. I can only assume the compression tester is dodgy... The other connection (snap on /"easy" release) is very hard to get on.

[nwxh]

Another question, sorry.

The compression tester has three parts which would appear to fit (if loosely) the spark plug holes. One is the end of a flexible hose, which also has a thread for a larger hole [C]. Another is the same but fixed [D]. A final one only has the one thread but is longer [E].

I wonder if I should have used the longer one, which I didn't use. Is this correct?[frame][/frame]

[bmcecosse]

You use whatever connection screws into the head nicely.. My own comp tester simply has a taper rubber at the end - and is simply pushed into the hole while the engine is cranked over... Simples !

[nwxh]

All of them seem a little loose and would surely be liable to give the same readings as earlier. All I can think of is to use engine oil to seal the threads more?

Nevermind, found a suspiciously similar model on amazon with very poor reviews. I'll buy a new one, and if I get higher readings, I can use it to justify returning the other.

[bmcecosse]

There does seem to be cr@p out there - I bought a laptop battery and it's absolutely useless.....They're trying to tell me my charger is faulty....works fine on the old battery...

[nwxh]

I prefer Amazon to Ebay. If multiple people post "tool snapped on first use", I avoid it. ;)

For the one that looks the same, 17 out of 24 people gave it 1 star. One quote, "I checked the pressures on my cylinders and they only showed 50psi. I had to buy another tester and that showed 170psi.".

But I'll reserve judgement until then new one comes.

[kennatt]

Without seeing it in the flesh,from the photo I would say E screws into block,to replace plug then C or d has a push fit into the end of E(c being a longer extention) Then C or D push fit into B. Is that the way you did it. Are you sure it was 60 psi not 160,which would be about a normal reading. If they were not fitted correctly and air was being lost then you will get very low readings. Can't belive they are that low,would think that it would hardly start or run in top gear..Just reviewed your post,it looks like you have used the wrong tester to block connector.,If you look at it, is it the same as the spark plug threads,this just screws in finger tight then give it half a turn or so to seal with a spark plug socket,then make sure the push pulls are in properly.

[nwxh]

Without seeing it in the flesh,from the photo I would say E screws into block,to replace plug then C or d has a push fit into the end of E(c being a longer extention) Then C or D push fit into B. Is that the way you did it. Are you sure it was 60 psi not 160,which would be about a normal reading. If they were not fitted correctly and air was being lost then you will get very low readings. Can't belive they are that low,would think that it would hardly start or run in top gear..Just reviewed your post,it looks like you have used the wrong tester to block connector.,If you look at it, is it the same as the spark plug threads,this just screws in finger tight then give it half a turn or so to seal with a spark plug socket,then make sure the push pulls are in properly.

Thanks. I didn't use E at all. I used D where the spark plug went. I can try this.

Only B has a push fit into C or D. I screwed D tightly into the spark plug hole to the extent of damaging the rubber, and it made no difference. The push fit is suspect.