TommyK would have unplugged it to do the compression test without getting shocks from the coil output voltage.

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1986 Mayfair (998 auto), 1974 S, 1974 Van, 1972 PMG Van

Too many minis

Slightly obvious question you may have already thought about and answered.. do you have a tacho? what's the idle speed?

Going by those plugs (aside from #3), it's running pretty rich, were the plugs you took out that dark? ever had a look at the plugs after a good 15-20 minutes at 100kph?

How does it perform if you drive it up a hill in 4th gear? - like the kind of hill where you start at the bottom at 3000rpm and you floor it, the engine holds those revs and chugs all the way up, maybe dropping to 2000rpm at the top.. is it happy to do it, or does it cough and miss and stumble and you have to drop back some gears to get it to rev

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did I tell you that I won a trophy?

When i checked the idle speed on my digital timing light a few weeks back, I believe it was around 800rpm at idle.

Now that you mention the colour of the plugs, I've done a bit of reading and they do appear a bit dark don't they. I've been out of the car scene for a few years and just naturally observed the electrodes and the very end of the tip.

To be honest the car doesn't get as much of a workout as it should. Most of the time it doesn't reach past 60km/h (around town driving). I think naturally I would drop down a gear if climbing a hill. Hopefully, this rain settles and i can give it a good drive, I'm a bit precious of the old girl in the rain

I'll chuck a new set of plugs in, rotate the dizzy drive and lean it out a bit. And then see if the problem transfers to a different cylinder.

One thing that I have noticed recently is that sometimes the vibration at idle is worse and sometimes it's slightly better (Still present though). I guess this is like a lot of issues though, sometimes they flare up.

Sorry, i didn't keep them in logical order. They are definitely lined up in the picture cylinders 1-4 from left to right. The picture of the gauge just so happened to be in number 3, I tested them all and randomly selected one of the photos as they all read roughly the same compression.

I didn't think of checking the gap at the different points of the dizzy cam! Unfortunately, it was not the issue though. Lead resistance was good. I'll swap the leads around and try that.

Dwell measured at 46 degrees. Which appears to be just in spec for a 45D

Update:

- I have replaced the spark plugs with new ones.

- I have leaned out the mixture.

- I have removed and rotated the distributor drive shaft 90 degrees anti clockwise so that the cylinder 2 spark is now distributed from approximately the 10 o'clock position of the dizzy cap, instead of the 2 o'clock position. This was in an attempt to see if the possible spark plug fouling remained at cylinder 2 or moved to the corresponding cylinder that took cylinder 2 original ignition point on the dizzy.

- After driving both at 100kph on highway and 50kph around town, i removed the plugs to inspect if the fouling was still present at cylinder 2 or if it had moved.

- The photo below (1-4, right to left) shows that the fouling still remains at cylinder 2 despite moving the ignition point at the distributor.

I'm guessing this is more related to the cylinder, valves, head gasket, cam, and/or rockers than the ignition side of things then.

The mixtures look really nice don't they.. except for that one... I'd say to put a hotter plug in it but they're already #5 - you could put a BP4ES in it and see if it burns whatever is getting in there

Did you find that #2 was down on compression? didn't happen to try another gauge did you?

Also assuming you still have the rough idle...

Where are you located? a second set of eyes to look over it while you both have a beer and nod your head might help fix it

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did I tell you that I won a trophy?

All 4 cylinders had approximately the same compression according to my compression tester. I haven't got access to another compression tester without buying one.

Yes, I still have the rough idle and it seems to run fine once up to speed.

I'm located in Wollongong. I've only recently moved here and haven't found a local mini guru like I knew back in Wagga.

There are a number of Ausmini members in the Gong. If they don't respond on here try a msg to one of them as they should have good local contacts to assist you.

timmy201 - Timmy

phillb - Phill

http://www.minisinthegong.com.au/

... and if you are Facebook user - https://www.facebook.com/minisinthegong

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

There are a few of us here in Wollongong, as Doug mentioned we have a group called Minis in the Gong who meet up for drives & have a show once a year. Unfortunately the last few years have been a bit quiet for various reasons but hopefully the weather will clear up soon and we can enjoy our minis!

If you’re after a mini friendly mechanic I’d suggest Bell Auto at Oak Flats. He’s been into minis longer than I’ve been alive and his workshop was full of them when I went for a rego check earlier this year.

I’ll have a check to see if I’ve got any useful parts you can borrow for some diagnostics

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Thanks Winabbey !

I've heard there are a fair few mini's in Wollongong but yes with all of this weather, I am yet to see many getting around.

I'll check out Bell Auto for sure! And thanks for your kindness.

UPDATE

I finally got some time to look over the mini again.

I bought another compression tester which recorded approximately 130 PSI at each cylinder. The old gauge read approx 90 PSI at each cylinder. Still, I scratched my head, it's better but still not ideal.

Connecting a spare spark plug to each lead, one by one I looked at the spark produced at each lead. I'm convinced they are all firing about the same, so once again I look towards an issue at the cylinder (not the spark).

Deciding I've fiddled around enough, i took the cylinder head off. The cylinder walls and pistons still look in great order, however, the same could not be said for the head gasket. There appear to be some markings between #2 and #3 indicating that compression may have been escaping between the two. even #3 and #4 look a bit suspect.

The engine was rebuilt a couple of years ago (not many km's). Both the block and head were machined by a shop that works on mini engines frequently. I'm wondering if the head gasket is a poor-quality one and is reflective of many other mini parts that are poorly made.

While you have the head off it would be a good idea to remove the valves in the suspect cylinder and have a good look at them and the seats.

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Cheers Dave.