General Engine identification
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General Engine identification
That's a good question and not easy to answer. Given that items get swapped out makes it even harder. I'm guessing that the internal shape of the cylinder head is a good clue and there may be numbers on the top which correlate. The engine number gives a good rough date of manufacture as do some date markings found on alloy parts. I know that camshafts changed with development, as did ignition setups and the generator. The muffler shape on the later models was cylindrical. I think you will find it hard to say which 650 you have without dismantling plus some guesswork. The real changes would be in compression ratio which increased over time and the valve timing according to camshaft. I doubt there's a massive difference in unmodified engines. Toshi 975 is most likely to know.
Always.[emoji3]
the hobbler
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Sorry to have to tell you, but I don't think that you have a 650 engine in your car. First of all, check the engine number---if the engine number will start with a "126 A1", then it IS a 650. If it starts with a "126 A", then it is a 594cc engine (500R/Mk 1 126). The main thing that set me thinking is that you have a generator on the engine----the Mk 2 126 (652cc) had an Alternator! I can't think of any sensible reason why somebody would go to all the trouble of retrofitting a dynamo to a 652cc 126 engine. The engine number can be found on a machined face, just to the right of the fuel pump.
What does it say on the block after "126"? Going back to your original question and as long as it's not "A5", it could be one of several versions of the 650. Please check this thread:
https://www.fiatforum.com/showthread.php?t=455808
Worth a closer look.[emoji3]
So congratulations. . at least we're back to square one as it is a 652cc block. The dynamo is not out of character as the early 126 did not have an alternator. So we can make a guess that it is the lower compression engine but perfectly good at that. [emoji3]
So congratulations. . at least we're back to square one as it is a 652cc block. The dynamo is not out of character as the early 126 did not have an alternator. So we can make a guess that it is the lower compression engine but perfectly good at that. [emoji3]
the hobbler
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Sorry to have to correct you Peter----but "126A" is only 594cc, and was used in the 500R and the first of the 126 cars and they had dynamos fitted. When they went to 652cc, the engine number changed to "126A1" and they were fitted with alternators.
Sorry..that sounds right. I'm away from homeand my references and I was referring back to memory where I thought that 126A5 was 594, but that was possibly just when fitted to a 500R., (or possibly not at all[emoji3]).
lazylobster
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My 500R has the 126A5 lump, so sounds about right 
There is an assumption here that the engine has been transferred as a complete unit but because of the interchangeable parts the engine could be a hybrid so I would still check the cylinder head marking and the carb code as well as it could be running a restricted 500R carb. Also I am led to believe that an economy model Fiat 126 was available in Poland that used a dynamo rather than an alternator so a dynamo may not automatically indicate a 594 engine.
OP
OP
hodgy18
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Not too disappointed no. But now Ill be able to find all the correct settings for the valve clearing, timing etc as I'm still having the cutting out when it gets hot. Fitted the spark plug lugs to stop the loss of sir and I've cleaned the carb out. Just need to do the other bits.
