Tuning Deciding on 650 upgrade

[romniox789]

I think my new 500 needs a few more horses to cope with the hills around me. Not urgent to change but starting to think about my options. Synchromesh box would be good too.

I think a 650 standard spec would probably be easiest to find and to maintain, but am not sure whether I should be looking for a specific engine model number, or a specific model number for the gearbox (or indeed variants to avoid). Any guidance?

Also, is there a definitive thread that explains how to do the engine and gearbox swap?

Many thanks

 

[the hobbler]

I think my new 500 needs a few more horses to cope with the hills around me. Not urgent to change but starting to think about my options. Synchromesh box would be good too.

I think a 650 standard spec would probably be easiest to find and to maintain, but am not sure whether I should be looking for a specific engine model number, or a specific model number for the gearbox (or indeed variants to avoid). Any guidance?

Also, is there a definitive thread that explains how to do the engine and gearbox swap?

Many thanks

Fitting a 652cc "126" engine (and gearbox) is not a difficult job. If you fit the 126 gearbox you will have to fit 500 25mm drive-shafts---the 126 drive-shafts are too long. Personally, i would retain the 500 gearbox--it is a stronger gearbox than the 126 variety. If you do fit a 126 engine, and retain the 500 'box, you will need to fit a 126 bell-housing to the 500 gearbox, as well as a 126 starter (they are in different positions on the bell-housing). A good source of 2nd hand 126 parts is "L.P. Garage" in Sudbury (Suffolk) Lukasz is a good guy to do business with.

 

[romniox789]

Fitting a 652cc "126" engine (and gearbox) is not a difficult job. If you fit the 126 gearbox you will have to fit 500 25mm drive-shafts---the 126 drive-shafts are too long. Personally, i would retain the 500 gearbox--it is a stronger gearbox than the 126 variety. If you do fit a 126 engine, and retain the 500 'box, you will need to fit a 126 bell-housing to the 500 gearbox, as well as a 126 starter (they are in different positions on the bell-housing). A good source of 2nd hand 126 parts is "L.P. Garage" in Sudbury (Suffolk) Lukasz is a good guy to do business with.

Why do you say the 126 gearbox is weaker? It’s a Sunday car so perhaps that’s less of a worry for me but intrigued…

 

[the hobbler]

Why do you say the 126 gearbox is weaker? It’s a Sunday car so perhaps that’s less of a worry for me but intrigued…

The synchros on the 126 box are the possible weak spots

 

[Toshi 975]

I do wonder as the years roll by if the opinion that the syncro gearbox is weaker is something of an old wives tale. Obviously with the syncro there is more to go wrong but it would have been a strange move for Fiat to deliberately introduce a weaker gearbox then to goon and produce millions of them for all 126 models including the more powerful Bis models and the final ELX with no further gearbox modifications.
As for engine upgrades for a 499cc Fiat 500 as some of you who know me will know that I have built many engines for our cars, standard and tuned, from 499cc up to 795cc. Engines have been either for my own use and pleasure or made for colleagues on request. Last year I realised that I had accumulated enough parts to build a “new” standard 650cc engine so I started a total build from a suitable bare crankcase. I almost finished the project before the weather meant it was too cold for me in the garage. So I stopped for the winter. Other projects diverted me but have been getting back to the engine lately. If anyone is interested in a totally rebuilt standard 650cc engine do feel free to contact me for details as the price will be extremely competitive. I also photographic evidence of the build.
The pictures show the current stage of the engine.