I've got a 63 Valiant and I would like to know which size engine I've got. Is there a serial # on the motor that will tell me what size motor it is? There's nothing obvious in the engine compartment (no sticker on the aircleaner)

Thanks!

Look for a number stamped into the top surface of the block, on a pad not covered by the head, near the alternator. That should identify it for you.

Look right behind the alternator, you may have to clean the location to see the numbers.
DD