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Sunbeam's 1973 Fiat 125


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Good evening Old Schoolers, I think it about time I posted this old thing on here.

Firstly, some history. Last year I bid on this car on Trade Me. It was being disposed of by Turners along with a whole bunch of other stuff from a private car museum in Blenheim, some of you probably remember it. I have been pining for another Fiat 125 for many years now as my first car was a Teal green 1973 125 with high back seats. I copped a lot of flack from my high school peers at the time for driving a "Lada" Philistines...  Anyhow, I did not win the auction, a Fiat collector from Hawkes Bay kept outgunning me and the Finance Minister was not happy for me to gun back. Wallowing in self pity for months after, I got a random phone call from said collector wondering if I was still keen on the car, as he already had several minter 125s and had just bought an Alfa he has been chasing for 20 years. A deal was done and he also offered to store it for me until I could arrange to get it back to to South Island because we were in the middle of moving South from Taranaki. I am very grateful to him for giving me first refusal and for being very helpful.

Whilst being transported to my new home, about 25km short of the destination, this happened.


The truck was involved in a fatal accident in Amberley. A local and well known businesswoman driving her Old School Civic crossed the centreline into the path of the truck and was unfortunately killed. I could scarcely believe it when the dispatcher told me.





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So, the car arrived safely (eventually) and got parked in the garage of our rental. So far I have not driven it far (about 3 miles in fact) Which revealed the brakes were a bit seized. This is hardly surprising as it hasn't had a reg or wof or been driven much at all in nearly 10 years. This inactivity is also why it's in such good nick.

Unfortunately I have lost all the photos I took when I first got it. Here is a gratuitous bum shot.



The other thing I like is that this car was probably registered in the same month as my first 125 because the number plate is only a few digits different. The interior is also identical. 

This baby has only done half the miles however, a gen-u-wine 72000 miles. All the more remarkable that this is 23 years after I owned the other one!

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First job was to fix the brakes. I have also lost the photos of this job... I'm shocked it managed to go and stop at all, let alone pull up in a straight line. I had to crowbar the calipers off the discs. Now, I like fixing stuff because my time is cheap (and I'm cheap). Sadly, I lack facilities in our current home. All my stuff is in a 20 foot container and the modern (clean) attached double (ha! how do you actually get 2 cars in a double?) garage is not a very good workshop. 

I took the calipers in to CBC in Christchurch and the lovely folk there rebuilt them and made them look brand new. Which is a good thing because the bill came to $736. Gulp. I'm a little bit insulated from workshop prices because I usually do my own work, so I tried to hide my shock when presented with the invoice. They did a lovely job though. While it was apart, I did the rear axle seals which were were weeping slightly. Also, I thought since my calipers look so nice, why not spend even more money and get new discs as well along with new pads of course.


Man I love getting new parts....


All four corners look like this now. Honest. Now I'm just a little bit worried about the mess I've made on the nice floor of the garage... I really miss my 12x9 metre man shed.

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So, as well as not having been driven in nearly 10 years, it also hasn't been serviced. I drained a couple of litres of creosote out of the sump and treated her to fresh 20w50 and a filter. After this, I replaced the air filter which was so soggy you could almost knead the rubber like play doh. There is quite a lot of blowby being pushed into the filter housing and I think this has led to the deterioration of the rubber. This morning I changed the gearbox and diff oil. The gearbox oil was dark but at least it doesn't smell of gear oil. The EP additives in most gear oils are liquid death for these boxes and your average joe mechanic has no idea.


The Castrol is what I used in the gearbox. The suction gun is great for jobs like this but it's very hard work sucking up 25w50 through a straw.


Also, I sometimes think I am the only person in NZ who owns a 12mm hex driver. The sump, gearbox, and diff plugs have all been massacred with vice grips. My old 125 was the same and the few modern(ish) Fiats I have done work on were also the same!!

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Some of you may be thinking "hey that's not a proper project car, it's too flash eh" So, to prove its pedigree, here is a rust.


There is another rust in the radiator support panel and I suspect a good quantity of bog in the front valance. Otherwise for one of these it's quite good. 

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Test drive yesterday revealed not so much a flat spot in acceleration, but more of a yawning abyss the car would fall into when throttle is applied too rapidly. I have mild whiplash as a result. Today's mission is to put all this


In here


Mum is in town and the kids have found a Rammstein CD and are headbanging to Du Hast in the dining room. Hilarious. Dad escapes to garage. Anyhoo, those green HT leads are original 1973 Cavis items. I got another box from Germany with rotor, condensor, points, and leads. Essentially shipped for free with the wheel bearings and brake stuff I was getting anyway. All parts were very cheap. Unfortunately I broke this while undoing, it's the insulator block in the side of the dizzy housing that keeps the points, LT, and condensor leads electrically seperate from the housing. Ideas where I can obtain another?


I can still use the inside bit. New high impedance insulator manufactured from Marmite lid for the outside..complete with special offset hole. Feeling quite chuffed at achieving some Barrying.


Test drive on the cards for this arvo. When I got it, the accelerator pump on the carb wasn't working so I suspected this at first for causing said abyss. It seems to be working now however, so hopefully replacement ignition components will fix it.

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Success! (ish)  Flat50acres is now merely a flatspot. The rest must be down to fuelling.  Put the timing light on it, idle set at 10 BTDC. Drives well, idle is a bit crap. I've spotted a rebuild kit for low $ on Ebay for the Solex carb.

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  • 5 weeks later...

The little Fiat seemed to be running horrendously rich. There was fuel oozing out around the emulsion tube due to a bad seal. Also, it turns out the mixture screw was set 7 full turns out... 6 and a half turns in later and it's much better. I took it for a good fang up the road and the plugs are a much nicer colour. 

3 days after this, a carb kit turned up.


So easy to get at, I love it.


Minutes later...


Take one of these and call me in the morning.



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I have fitted the carb kit. This is the easy bit. It did fire right up but doesn't actually run any better. Now, according to my manual it seems my particular Solex carb C34 PAIA/9 is an "exhaust emissions control" model. These words strike fear into my heart as this is usually a euphemism for "this is a shit carb and you will never get it to run properly". I must admit I am a bit of a noob when it comes to carbs (except for dirtbike carbs). I have a few questions for those more knowledgeable on the subject.


Firstly, the screw outlined in red. None of the diagrams in the workshop manual show it. This was nipped up tight when I disassembled it and so I did it up the same. Twisting it with the engine running even 1/8th of a turn has a profound effect on the sucking noise the carb makes. I have no idea what it does. The blue circled screw is the idle mixture adjustment.


Secondly, none of the diagrams show this spigot either. There was nothing hooked up to it, but it is sucking air. Blocking it with my finger with the engine idling makes it die.


Thirdly, fuel is weeping from the red lined area despite the fact it is a new gasket, the surfaces are clean and look flat, and the fuel level in the float chamber is 12mm below this line. Actually I don't know if this is right as I can't find a correct float level anywhere in my books or on the google, just reference to special tool xyzabc to bend the float arm correctly...


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The Fiat is running well on the road, but there are some starting and idling issues and transition issues to deal with. The first thing I have done is block off a vacuum take off that had nothing on it. This is clearly a source of un metered air and I had to tweak the throttle stop/ idle adjustment about 4 turns to compensate.


I've just been for a drive to get the engine fully warmed up , re adjust the idle speed and have another twiddle with the mixture screw. I think the tip of the screw or the seat may be buggered because only when the screw goes tight does the idle even begin to pick up. I think the engine would prefer to idle a touch leaner even. I'm still baffled by the 3rd screw on the carb. I cannot find what it is in any literature I have or indeed the googlebox.


I have had a fiddle with it, but I don't know what it's doing. I can see the results though... As received, this screw was snugged into its housing. backing it out half a turn increases the idle by about 1200rpm, but does nothing for the hesitation in pickup. I suspect the hesitation may be related to insufficient fuel from the accelerator pump circuit, although the pump diaphragm and seals are brand new. I need to find out what the mystery screw is anyway, it will drive me mad otherwise. Also takes a lot of cranking to get going when cold. These poxy carbs don't have a traditional choke either, it's some sort of magical enrichment circuit...


Or this...... currently on TM for 6 hundy. Wrong manifold tho, for a worked 4K. Too much $ anyway for now, but we can dream. 


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  • 4 weeks later...

I have been mucking around with the carb. It still leaks fuel along the gasket line. I think I figured out some of what the mystery screw is for. I think it's some sort of air correction device. I have decided to leave it closed, because if you open it up some, you get a wicked backfire in the primary throat when you blip the throttle... It has also been sucking at cold starts. I have had a play with a 34 DMS Weber that NickJ lent me which is real good at cold starts. Unfortunately the DMS requires substantial linkage mods to be able to work, and I don't want to go down that road just yet. I think some of the issue has been with the Solex carb's lack of accelerator pump output. So I have pulled it to bits again and double checked the jets and passages which are all clean.


The jet sizes are all factory or very close to factory. It's hard to say for sure though, because there are so many versions of these carbs. I did find a problem however...Item 43 in the diagram below has a crack running right through the threaded hole on one side. I'm not sure how this will affect the operation of the accelerator pump if at all.


Upon reassembly it seems it's pumping quite well, and the car started easily and did not bog down when blipping the throttle, so I went for a drive to get her warm. The idle drops significantly when the engine is at operating temp, and also the accelerator pump output drops, and the hesitation/bogging down starts again.

Interestingly, reaching in with a hand to crack the secondary (while the engine is idling) reveals good, crisp pickup despite the secondary not having an accelerator pump jet. I am confused! 

I need to find a parts carb to swap out the cracked plate in the accelerator pump I think.

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  • 3 weeks later...
  • 2 months later...

Update time, although not much to report on the car except it's still idling poorly. 

We have had a few dramas of late at the property with the recent heavy rains.  The road culvert is not big enough, and more importantly, the shed leaks. A lot.



Yesterday was a nice sunny day so apprentice no 3 and I took the Fiat for a drive. It's going well except not idling and the accelerator pump circuit is not working. I'm saving for another carb setup.

I also noticed the lines from the brake fluid reservoir to the master cylinder are "sweating" brake fluid. Never seen anything like it.


In happier news, I bought a compressor! Now I just need to pop a 15A socket in the shed so it can work...



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  • 7 months later...

Well, it's been a while...I do have a good excuse though, we are building a house and have been living in a 40 square metre portacom since pretty much my last post, so all my spare time has been directed to the build. We're trying to get moved in before winter really bites. 

Would you look at the state of my shed....


However, I have done a Fiat related thing recently. My finger got real busy clicking and resulted in purchasing THIS:


See you in 6 months...



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  • 4 months later...

Hi everyone. Having got back from 5 weeks overseas and on the back of finishing and moving into the house, I took pity on this thing today and dug it out of the corner of the shed.


Fired up nearly straight away. Pretty good since it hasn’t moved since January. Then I got all fired up and thought I’d flush the cooling system. It has gunge floating in the expansion tank and I want to clean out the whole system and see if it comes back. 


Looks a bit suspect but it doesn’t overheat or pressurise the cooling system, or milk up the oil so I’m not super worried at this stage. Anyways, I thought while I have the hoses etc off, I should do the cambelt too, so I started getting the tools out, making a plan of attack, and then.....meh. Jet lagged. Maybe later.

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I had a half hour spare yesterday morning so I started to dismantle the front end with a view to draining the cooling system and gaining access to the timing belt. The drain cock on the radiator opened easily (phew) as did the engine block drain tap. The coolant looks very clean and green, like a NZ river....


I am quite encouraged by this. Now look as I add the contents of the expansion tank...


The stuff is a greasy sludge. The seal on the radiator cap is also greasy to touch, but I’m not sure there is actually anything wrong. I did have one thought, I have heard the odd Barry go on about putting diesel in the cooling system for pickling purposes when parking a car up for ages. This car was parked up for ages. The coolant looks fresh, so maybe the residual oily crap has made its way and become trapped  in the expansion tank in the 100 or so miles it’s travelled since being liberated from the museum it came from.?

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So, the radiator is a bit of a prick to remove compared to the Vogue I was working on a couple of years ago. I can’t get my ham hands onto the bottom hose for starters. The top hoses came off easy and happily there is very little corrosion on the alloy fittings. You then have to split the fan shroud and wrangle the top half out which only just fits. Then its just 2 nuts, tilt toward the engine and pull up and out. There’s not much clearance though, and not helped by the thermostat still being attached by the bottom hose due to my inability to undo it in situ. The radiator looks new. Next I popped the grille and headlights out (easy peasy, thanks Fiat). Now I can have a good look around. First impressions were the battery area looks good for a 45 year old car.


I can also see a lot more rust. Some expected, and some not! This is the left park light/indicator. You can see its rusted out around the wiring grommet.


And the reverse of this...


So there’s A fair bit of rust where the inner guard meets the nosecone. And then there’s the stuff I knew about. This pic is the radiator support area.


That’s Taken slightly upside down, the white area is my shed floor. Next I took the fan off and rattled the securing nut off the fan clutch/hub but now I’m stuck. I need a puller and I don’t have one. I’d also like to remove the crank pulley but my biggest socket is 36mm and the nut is bigger! Also no room for a rattle gun. Also interesting to note, the crank pulley is not a damper type. I think this is the first motor I’ve worked on that doesn’t have a damper pulley.


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