Technical 500 Nuova Engine Rebuild

500nuova

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Hi, I joined this forum today so let me begin by saying I have a -58 500 Nuova America "bug-eye" and a -59 Bianchina Transformabile.

I'm rebuilding the engine on the -58 Nuova, it will need new cylinders/pistons/rings etc. I would like to use the original crank case, since it's numbers matching. It's the 479cc and I'm having a hard time finding new parts for it.

So I'm wondering if it's possible to use the existing block with 499cc or bigger cylinders etc? What would be involved in the conversion?
 

the hobbler

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Welcone to the Forum---we are here to help. As far as I am aware, you can fit the barrels for a 500 (and therefore 540cc barrels) to an early '479' by enlarging the barrel apertures in the crankcase. The 540cc barrels are normally a straight swap with the 500 barrels on the '500' engines. If you wish to confirm that you CAN do this, contact Middle Barton Garage or Proietti (in London). Where about are you?
 

Bigvtwin996

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you should be able to get teh original barrels rebored and fit teh later 499 pstons...

Please always take this approach... whilst 500Ns look like later cars very little is the same...
N parts are very hard to find... very few dealers have any stock simply because very little is remade... Most dealers have never seen or owned a 500N.


Email Andrea a Passione 500 in Italy.. he has some N engine parts and knows many N owners... tell him peter from the UK told you to speak with him...
 

the hobbler

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Going from the 66mm bore of the original '479cc' 500 engine to the 67.4mm bore of the 500cc version would very possibly leave one with very thin barrels. I would suggest that one of the questions you ask Andrea (at 'Passione') is whether this is a viable AND RELIABLE proposition.
 
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500nuova

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Thanks for the information! Much appreciated. I will contact Andrea at P. as you suggested.

On a related note, I have the original transmission with the 19mm (?) drive shafts. Just looking at them I marvel that they can handle the "power" from the 479. Can they really deal with more output, or would I have to go up to later drive shafts as well? Will those even fit my car?

Reason I ask is I would like to keep it as original as possible, and not open a can of worms by making too many modifications. But as you know parts availability is always a concern in our hobby and I want to see them back on the road. It's a fine balance to walk...


By the way, I have not yet figured out how to use the search function on this forum (I only get thread titles???) so I apologize if the answers already exist somewhere else on the forum. I promise I will get the hang of it eventually. Anyway, thanks again for your responses and patience!
 
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500nuova

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Since you asked, I'm in rural Virginia. More Camaro country than Fiat, but what can I say?
 

the hobbler

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You have some good driving roads in your part of the world, and you are more likely to be able to enjoy the views trundling along in a 500 than you are skelping along in a Camaro (or Mustang).
If I remember correctly, the rear suspension 'arms' on a '479' are shallower than on the later 500s, so you might not be able to get the later 4-bolt couplings inside the arms. There is also the chance that the rear stub axles are of a smaller diameter---Andrea should also be able to answer that query.
 

Bigvtwin996

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the N Sport used the same barrels and crankcase..
It was over bored to 67.4mm an increased cr to 8,6 : 1
New carb and cam and produced 21.5 bhp
So fiat already did it... the later engines were based on what they did with the Sport...

N rear arms will not accommodate the later F/L couplings without a lot of hammering...
I think there are conversion kits to use 25mm shafts...
Do you have the 3 or 4 bolt couplings?


Brakes etc are also different to later cars...


If you want excitement ft a 650 engine with the std shafts and accelerate trying not to snap one!!

you have opened the can!!!
one option is to try to convert all the running gear to later spec and keep the original... it will make the car more serviceable...
You can rebuild the original stuff at your convenience then...
 
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500nuova

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Thanks again for your thoughtful comments and suggestions. Much appreciated.

bigVTwin - The thought of installing more "modern" 650 drive train has crossed my mind. In fact it's the way I'm going with my -59 Bianchina, if/when I can find a good donor car within my budget. The -58 Nuova is so original and the "bug eye" cars are getting rare in the United States so if at all possible I'd like to keep the 100% numbers matching drive train in the car. But the motor definitely needs a rebuild - hopefully Andrea at P. can help me out.

hobbler - You're right about the roads. Some great driving in the Blue Ridge Mountains foothills. Nothing like going "fast" in a slow car! And we're not very far from the Smokies with some truly legendary roads like the Tail of The Dragon, although some of them are as congested as the Stelvio or the Ring nowadays. Also, we're 30 minutes from the VIR circuit, that has some great vintage racing. All in all not a bad place to be.
 

the hobbler

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I have messaged you direct--if you come back to me direct (tommontagu@yahoo.co.uk) I will help you out best I can
 

Bigvtwin996

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You will find many people on the Forum who have highly modified cars....
Other than widening the arches for wider wheels... many things can be reversed should you choose to later...
the N in original spec is actually quite dangerous by modern standards... if you lived in a small town or village it would be a great car for popping to the shops...

It s possible to keep the original look and update the mechanicals... and as I have said to update an N to Sport spec it would look exactly the same as the original inc engine number....

a 650 in std form is about 24bhp... I dare say you could get closer with a better carb (Dellorto) on a Sport Spec engine....

A lot is about "Useability" and servicing.... early stuff brake cylinders etc are hard to find you can use later ones though so out goes the "originality but who would know..... a disk brake kit is bolt on and easily reversed and is easy to maintain as well as a bit of extra braking...

It would be worthwhile having a good read of the Forum and see what others have done to later cars to make them more "useable", after all it is great to see a classic on the road....

If you pulled up in an N with a Syncro box and 650 engine and disk brakes, no one would be any the wiser unless they understood engine numbering and started looking really closely ...


Ohh forgot to mention Andrea is away till the end of august - He likes his holidays!!
 
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500nuova

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Many thanks for all the comments and PMs!


Usability and safety is definitely a concern in this era of gargantuan trucks and SUVs. The "modern" cars that we use every day are from the 60s and 70s and they're quickly becoming marginal in that regard.


The master plan - if it pans out - is to keep the Nuova as original as possible and use it around town and upgrade the Bianchina in terms of safety and practicality.


Things on my initial to-do list for the Bianchina include wheels and tires, a dual piston master cylinder of some sort, and do something about upgrading the power.

As far as the power part goes, I'm considering using a 650cc or 126 engine with the dual port head from a Panda for a fake-Abarth-ish setup. And do whatever it takes to make the rest of the running gear handle the near-double output I'm very optimistically hoping for. :)
 

the hobbler

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Contact me with your e-mail address, I have an interesting piece of paperwork for you regarding tuning the 500/126 engine. Totally agree with your idea of keeping the 500 as original as possible and tuning and upgrading the Bianchina.
tommontagu@yahoo.co.uk
 
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500nuova

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Interesting stuff and so much food for thought!

I didn't realize the N Sport's compression ratio was that much greater than the other versions. How was that CR accomplished? Different pistons? Different rods? A "skimmed" head? A combination of above?

Also, are the Sport cams still available for sale somewhere?
 

the hobbler

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I reckon that it was a combination of more swept area (20cc---5%) and possibly a skimmed head. Abarth MAY have used 'domed' pistons--they did on some variants. As to the availability of the 'sports' camshaft,Andrea may be anle to help you on that question.
 

Bigvtwin996

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Interesting stuff and so much food for thought!

I didn't realize the N Sport's compression ratio was that much greater than the other versions. How was that CR accomplished? Different pistons? Different rods? A "skimmed" head? A combination of above?

Also, are the Sport cams still available for sale somewhere?

I think the Sport CR was just a head skim...
but there are some fancy pistons about (and were in the day)
Have a read of Seans thread (Franko 500) about his D restoration, he found some interesting pistons when he stripped the engine..

I am sure there are many on here who could recommend a useable cam to pep things up...
Even some carb changes would look period so no worries there...

There is never a substitute for CCs and pushing a 500 for max power can introduce other problems
 

TeleSpeed

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I have a new old stock set of Nuova Sport pistons in the original boxes and they are definitely higher compression domed pistons compared to those fitted to the standard 500. Next time I go to my car storage facility, I will snap a few photos and post them here.
 
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TeleSpeed

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Nuova Sport Piston pic 1
 

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