Harry Metcalf of Harry's Garage recently posted a video of his re-engined Nuova 500. He had a trusted expert install a 695 cc engine in it. As it happens, I bought a 500F about 10 years ago which was described to me as having a similar over-sized engine. In Harry's video, there are allusions to several visual differences between the "big block" and the 595 cc engine. Does anyone know about these? I was under the impression that the only real difference in engine displacement size occurs in the bore, suggesting removal of the head to measure it. Thanks, Barry Koch
Technical 695 Engine?
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Technical 695 Engine?
If it's just the pistons than yes, you would only know about it when you measure the bore. But more likely there will be some other clues as well! Usually you don't upgrade just the displacement as this is a job for a specialized machinist. To make the most out of the 695cc they probably would have fitted a different camshaft but also a larger carburettor and sport exhaust. So if you have a larger carb fitted it would make sense to investigate further. If everything visible is still stock than you probably don't have a bored out engine.
the hobbler
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If the conversion is done properly, and the exhaust and carb NOT changed (and a number of the Italian tuning sites offer an 'up-rated' 650 engine with a basically stock carb) it will not be obvious what has been done to the engine. I am in the process of building a '695SS' engine to go into my "Abarth 695 replica" and after the thickness of the spacer-plate between the crankcase and the barrels had been arrived at, I only had to slightly elongate a few of the "engine-shrouding-retaining-bolt holes" ---I did NOT have to go to the trouble that Steff Proietti had to go too in order than the shrouding fitted! Looking at the video, I think that the barrels that he used were only 80mm (deep) barrels, whereas the standard Fiat barrel-depth is 90mm. I am surprised that he didn't just fit a 10mm spacer (or whatever thickness he required) between the barrels and the crankcase---it would have saved him a heap of work. My kit had the required con-rods included in the kit. Sadly, as "Dirkdeman" has already pointed out, the only gaurenteed way to know what your engine size is would be to remove the cylider head and measure the bore. The bore for a 500 is:---70mm; for a "595" it is 73.5mm; for a "652" (Mk 2 '126') it is:--77mm and (usually) for a "695" it is 79.5mm. I say 'usually' for the bore for a 695 engine because Mr Abarth, not having the stronger 126 crankcases available, and knowing the limitations if the 500 crankcase, went the "square" engine route---76mm bore AND stroke (using a very expensive longer throw crankshaft).
Also, as an aside, that fuel-filter that is on Harry's ebgine is both unneccesary and in (what I consider) a dangerous place. There are, from new 3 filters already in the system (Tank-unit, fuel-punp and carburettor top)---why fit a PLASTIC 4th filter in a place where if it should leak will drip onto the alternator. I hope this this answers your questions, but always feel free to give my"little grey cells" a rattle---- [email protected]
Apologies if this answer is too obvious to be helpful, but it's possible that when the previous owner said your car has an over-sized engine, they just meant that it had a 650cc engine from a 500R or 126. These engines can be easily distinguished from older Fiat 500 engines from the outside by the 126A engine number stamped to the left of the cylinders, the presence of an alternator, and the placement of the starter on the side of the bellhousing.
the hobbler
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At the riskof being rude to you Rusty, the 500R engine would be 594cc, the same as the 'Mk 1' 126 cars----they only went to 652cc on the "Mk 2". 126 variants. When Fiat first built the 500Rs they realised that being the 500 was lighter than the 126, the 500R was quicker than the 126, so they choked the performance by fitting a small 24 IMB carb---all the 126 models, irrespective of engine size, used a variation of the 28 IMB. AS 'Rusty' has mentioned,the engine number is on a machine-flat, to the left of the barrels, just by the fuel-pump. Some of the the early 126 engines had dynamos, so this not always a good guide.
Not rude at all. I appreciate the opportunity to learn from your helpful correction. Now I know about the MK 1 versions.
