Technical 500 Nuova Engine Rebuild

[500nuova]

Thanks for the pictures! Yes, those seem to have quite a bit more "meat" than the ones in my car. Very interesting.

 

[500nuova]

This is to the member in Ashburn, VA: I somehow managed to delete your PM when I tried to respond. Fat fingers, I guess... So if you didn't get my response, please contact me again.

 

[Toshi 975]

This is a 540cc conversion piston in the cylinder , I believe it was made by Nanni. It has a raised crown with the relief for the valve heads. It was new old stock and required a bit of rescue and only has two piston rings that cost me an arm and a leg for the set.

 

[the hobbler]

Very interesting; I was pretty sure that Abarth used domed pistons in the 500 'Sport', and BORGO were the pistons of choice for Abarth. That and the 5% increase in engine capacity would explain the 8.6:1 compression ratio of the "500 Sport"
When I was building up the engine in my '655 replica'I was looking for +.04mm pistons---and all my normal supplier had in that size were----a set of ORIGINAL Borgo pistons---NOS, which had been sitting on his shelves for a long time. I sure as hell snapped them up quickly!
Now, it would be fantastic if "Telespeed" would sell those pistons to Thor (Nuovo500) so all he had to do would be to (a) see if his barrels would safely bore out to 67.4mm (from 66) and (b) if they won't, obtain a set of 500 barrels, lightly skim the head, get a 500D camshaft (still available) and he has got, with very little work, a "500 Sport" specification engine.

 

[the hobbler]

Sorry, slip of the digit---I was looking for +.4mm pistons--brought the engine capacity up 659cc

 

[Bigvtwin996]

Now this is getting interesting...
taking a 479 to sport spec...
Tom are you saying a D cam is the same as a N Sport one?

Can we not take one of those Sport Pistons and do a Burt Munro

 

[the hobbler]

Yes Peter---according to all the books that I have, the cam-timing for the 110.004 engine (500 Sports) is exactly the same as the cam timing for the 110D engines and 110F engines--25/51/64/12 (plus the 120.000 Giardy engine)

 

[500nuova]

Toshi & Tele, Thanks for the pictures! Fascinating and very educational for a newcomer like me.

 

[Bigvtwin996]

Yes Peter---according to all the books that I have, the cam-timing for the 110.004 engine (500 Sports) is exactly the same as the cam timing for the 110D engines and 110F engines--25/51/64/12 (plus the 120.000 Giardy engine)

so the later cars do have a use as cheap source for N upgrades...
what would be "one up" from the std D/F/L cam?

 

[the hobbler]

Possibly a late '126'cam (slightly different from early '126'). However, you MIGHT have to fit a '126' oil-pump AND timing-chain cover, so that (a) the drive sprags on the pump match the camshaft and, (b) the '126' is slightly deeper. If you run a '126' pump in a 500 timing-chain cover you run the risk of not having a lot of oil-pressure when the engine is hot as the relief valve expands (due to heat) and opens too soon.

 

[Mferg]

This is to the member in Ashburn, VA: I somehow managed to delete your PM when I tried to respond. Fat fingers, I guess... So if you didn't get my response, please contact me again.

Didnt get your reply - will message again.

 

[500nuova]

First off, many thanks for all the help and suggestions! Extremely valuable for a 500 "newbie" like me.


I happily admit I'm a 100% green-horn novice when it comes to Fiat 500 engines, but, assuming they're not too dissimilar to other engines, it seems one would get into a point of diminishing returns by increasing the cam's duration and/or overlap without addressing the siamesed intake port somehow.


So please forgive me for opening another can of worms, but I can't resist: Bigger intake valves seems like a great idea for starters, but where does one go from there? Apart from going the path of a head with dual intake ports, would a port divider plate be helpful? Would increasing the intake port diameter help or hurt, and if so, how much is too much? Any thoughts on this?

 

[the hobbler]

All will be resolved when you get the letter that I have sent you. It explains about the porting, what size valves to up to and various other ways to enhance the 110 engine. With regard to the inlet port. you can open it up by about 2mm, basically to match the bakelite spacer and the carb choke size. When 'porting' a cylinder head, the inlet ports only require smoothing, but the exhaust ports must be polished. Whether the Panda30 will give much more power than a well ported standard '3-port' head is a debatable point. Technically, the Panda30 inlet ports are too close together. This is mainly because Fiat only designed them to be used with a single carb; if they had moved them much further apart, this would have led to complications regarding the shape of the inlet manifold---the carb would have had to be mounted much higher to prevent the inlet manifold having very sharp bends in it. De-siamising the inlet port I don'tthing will gain much a noticeable improvement in performance--and will be hard to achieve. Always be aware that you are basically trying to RELIABLY improve the performance for a ROAD car. Reliability is more important than getting every 1/2 hpout of the engine.

 

[Toshi 975]

Just to clarify Tom’s postings a tad, you cannot fit a 126 oil pump into a 500 engine without changing the whole timing chain cover. The gears are simply too deep. The inlet port on a 500 is 26mm diameter but on a 126 the spacer and inlet port diameters are 30mm. Although the Panda 30 has a single carb it is a twin choke Weber 30DGF with progressive butterflies which works quite well. The 30DGF was a more modern equivalent of the Weber 30DIC which was a traditional tuning carb for the little Fiats.

 

[the hobbler]

Thank you David for your input--it is very handy having somebody to tie up one's loose ends! I should have clarified my definition of a "single carb" better.

 

[Toshi 975]

You could keep your eyes open for a rotted out Giannini 500 and hope it has the original engine. There were 4 versions going from the 22hp 500 TV, 27hp Montecarlo, 586cc 28hp 590 GT to the 586cc 35hp Vallelunga. The latter two models having a 73mm bore as opposed to 67.4mm.
Mind you a non rotten one would be nice but I imagine very expensive.

 

[Toshi 975]

Spec in Italian

 

[500nuova]

David, Interesting thought if I could find one, but "if" seems to be the operational word. Clapped out Gianninis apparently don't grow on trees around here.

But you started me thinking about something else, namely oil coolers for the Bianchina. (That one's going to be my "hot rod", keeping the Nuova America's original appearance intact.) I scoured the forum and I see that some people tap out from the oil pump, drill a 2.5mm hole and whatnot, but I have another thought. One of my spare oil pans has a threaded bung near the drain plug. I'm thinking of using this a the "exit" along with an electric pump to take hot oil to a front-mounted cooler.

My question is: What would be a good way to get the cool oil back inside the engine again?


Or maybe my question really is: Is this really a dumb idea, and if so why?

 

[the hobbler]

Hi Thor;
The normal way that fitting an oil-cooler on the 110 +126 engines is to take oil from an addition on the front of the timing-chain cover and, as you say with the hole down the centre of the DRIVEN gear blocked off and then the 'blocker' through drilled with a 2.5mm hole. The oil FROM the cooler normally goes back into the engine through the pre-tapped and plugged orifice (posh word for "measured hole") on the edge of the crankcase, by the timing-chain cover----at about "half past 1" as you look at the engine from the timing-chain end. I will send you a picture of it. I can't see any sensible reason as to why your proposed idea won't work---it's just that it is another electrical item to fail! In most cases, I find that the 3-1/2 litre aluminium sump is quite adequate at keeping the engine cool, at least it is here in the UK. There is a 4-litre version available, which technically you should use with the oil pick-up extension kit.

 

[500nuova]

Thanks Tom,


We've had a very hot summer around here, the ground is baked so dry that the rain just washes off. Ha;f expecting tumbleweed and armadillos to show up one day! So additional cooling of some kind might be nice. I will definitely add an oil temperature gauge to the Bianchina. The Nuova will retain its dash bone stock.


I figured an oil cooler sitting up front in the airflow would be most efficient, but when I think about it a large, finned sump also sits in the airflow, at least partially.


If I take the electric route - the jury is still deliberating - I wonder if I should take the opportunity to create two more potential oil leaks by inserting a remote filter in the same loop?