Customers who are buying all of their parts for an engine from us will be assisted with calculating their CR, shims, spacer needs at the time of their engine parts purchase to be sure they get what is required.
For those that only need to buy spacers, we will calculate what spacers will provide what CR at the time you are ordering the spacers. What is required is for you to trial assemble the engine and provide us with the existing deck height. This could be with the piston below the top of the cylinder or how much is sticking out.
We always assume piston below the top of the cylinder so you must tell us if it is sticking out. We must also know the bore and stroke in mm, the head cc's and the CR you intend to use.
For further information on compression ratios purchase also see;
GB 801-CR, on deck heights purchase
GB 801-DECK and on heads purchase