I assume you mean a 948cc (looking at you previous posting photo) in which case it will be cheaper to get hold of a 1275 in the first place as it will have a stronger crank, better cylinder head ect in the first place.
Going back to your other post there doesnt appear to be a heater hose leaving the engine tap at the back of the block does the car have a heater ?
Cheers
Kevin
Lovejoy 1968 Smoke Grey Traveller (gone to a new home after13 years)
To answer the original poster - it is NOT possible to turn your engine into a 1300 - you can as Kevin points out - fit a 1275 engine from a Spridget relatively easily - or from a Marina/Ital with a bit more work. In either case - you should look to improve the brakes before doing anything to the engine !
To answer the second poster - welcome to the Forum - yes the engine can be upgraded - get a copy of Mr Vizards book on Tuning the A series (plenty on ebay) and read it from cover to cover! Same idea applies about improving the brakes first - especially if you have the early 7" front drums which were standard on the 948 cc cars. The later 8" drums from a 1098 cc car are much better.