Lude Generation

Sorry for the noob question but how do I find out which block I have AAA or BBB? The little metal plaque says my engine code is BB8 and it's a h22a5. I'm planning on doing my engine rebuild soon and I've bought some AAA atr pistons to go in but as I said I'm not sure what block I have and if they will fit. Cheers.

On the belt side of the engine look where the head joins the block. On the back of the engine there is a little narrow "shelf" right near the belt cover, and the letters are stamped on it. It will no doubt be covered in gunk that will need to be wiped away before you can see the letters.

Okay thanks mate, do you need to remove any covers or anything to see it? Cause everything is still in the car atm.

You should be able to see it although have never tried to on an engine in a car.

The H22a (of any variation) block obviously has 4 cylinders, the A or B piston designation refers to the ACTUAL size of the piston and the block is stamped to indicate the ACTUAL size of each individual cylinder.
The blocks are stamped as Merlin rightly pointed out and it is visible without removing anything but the area will require a scrub.
Finding a AAAA or BBBB block is actually more unusual than a combination block. You will usually find a combination such as AABA or BAAB or to be frank any mix of the two.
The pistons should be matched to the corresponding cylinder for correct clearancing - This obviously assumes new or non worn components, if using "used" items then accurate clearance measuring will be required.