Engine Blueprinting Part 3

The engine block is the foundation of any blueprinting project. It is the main structure of the engine of which each and every part depends on.

Starting with a good ‘well-seasoned’ used cylinder block is better than a new one as they get better with age. In the case of a cylinder block, countless cycles of heating up and cooling down help to ‘season’ the metal.

Once the block is cast in the foundry it is sent to the machine shop where it undergoes multiple milling and boring procedures and this develops internal stresses. The heating/cooling cycles during its initial life helps the block to relax which enables it to eventually become dimensionally stable.

Whether your engine or block is a BMW or Range Rover V8 motor packed and wrapped on a shipping crate or coated in grime, a thorough inspection is mandatory and looking for fatal flaws before investing in any machine work could save you hours of time and money.

Rebuilding an engine block with a history that you are familiar with is always an advantage because you already know if the motor was basically sound. Buying an engine block from a motor scrapyard is a riskier proposition as you don’t have the benefit of hearing the engine or seeing the vehicle from which it was removed. Was the engine simply worn out or was it filling the oil pan with coolant from a crack in the block?

Before a detailed inspection can commence the block needs to be stripped and degreased by soaking it overnight in a tank filled with a chemical solution. The block is now ready to be inspected for cracks and any other informalities such as blocked or contaminated oil passages which can only be cleared by high pressure cleaning and using gun clean. In all cases the oil galley plugs must be removed and the galleys reamed out.

The block is now ready to be deburred and polished by grinding off all the casting marks and any unwanted jagged metal edges that can hinder oil or water flow and helps stop cracks from finding a starting point.

The main bearing housings must now be checked for alignment to ascertain if they are aligned with each other and if they are round. Again, with either engine failure, high mileage, or over-heating, they probably aren't. The solution is to line-bore them into alignment and back to their original size. This ensures that all the bearings and crankshaft main journals will once again fit their housings in a perfect line. Re-tap all the bolt holes in the block to clean up the threads.

The blocks eight cylinders can now be bored or honed unless they are coated with nickasil. Boring and/or final honing each cylinder to match the oversize pistons will leave them once again round and true. Lastly the blocks decks probably require skimming and the cylinders entry edges bevelled for easy piston ring entry when being inserted into the bore. Finally douse the block with engine cleaner and pressure wash thoroughly. 

CLICK HERE for information on engine blueprinting or when sourcing a professionally reconditioned BMW or Range Rover V8 engine.