You will see many engine builders who advertise they use a new factory block, they sell this as an advantage.  The fact is with factory type blocks (this excludes performance blocks) you are better off with a seasoned used block.  A new block will tend to "walk" and distort slightly when heat cycles are introduced to it.  A seasoned block will have done most or all of its moving so the subsequent engine builds will be much stronger and longer lasting.  Although not as true for aftermarket performance blocks the same does hold true.  Even an aftermarket block do some moving or "walking".

Another critical component of block selection is making sure you have the strength to hold up to the power you are going to make.  Often a factory block is strong enough but many times it may not be.  You don't want to put thousands of dollars of performance parts into a block that can't take the power.  Other key factors are the desired oiling system (wet sump or dry sump) and the type of block cooling system (Siamese bore or standard bore).  Don't worry if you don't know what all of these things mean, a consultation with our engine masters will make sure you make the best selection.  Share with us what you plan to do today and in the future and we will make sure you select the proper core for your engine build.

(Picture of a Boss 429 block)

Line Hone/Boring:

The first step after selecting a block is to make sure the crankshaft bore is straight and true.  Also you need to make sure the bore diameter is still within specifications required for your particular build.  Many have used plastigauge to verify the main bearing tolerance but did you know that wasn't 100% accurate?  The actual clearance of the main bearing is not the same the whole way around the bearing.  The proper way to verify main journal bore is to use a very accurate and precision dial bore gauge. 

(Picture of a block in the process of being line honed)

Block Decking:

Decking the block is the second step in making sure everything is true and square.  By decking the block you remove any manufacturing or heat induced flex or warp in the block.  When a block is decked it is inserted into a special fixture that used the line bore as the straight line.  The top of the cylinder bore (where the heads will bolt on) is machined perfectly flat.  It is not uncommon to see a new block with 10-15 thousandths "warp" in the block.  If the block is not decked you are not guaranteed a square engine and when the block is bored you may end up with bores that are not square with the crankshaft.  Decking the block is very important.

(Picture shows a block decked at 5 thousandths that still shows excessive warp)

Boring:

Boring a block can be very truth revealing on how the block can handle heat and stress.  A block with bad heat cycling damage will often show a "window" in the bore where the piston has been forcing the bore out of round.  If too much of this shadowing is present it probably means the block has a pore metal content and should not be used.  Most production shops will just set the boring bar to the final setting and not take the time to shallow bore and check for shadow.  If this step is skipped you may not find a weakness that could cost you big dollars later!

(Picture shows a cylinder bore with a wear window caused from the block heat cycle moving the bore, this is typical and shows normal movement.  Excessive movement will have larger shadows that can often not be machine out)

Honing:

After the block is bored it must be honed to size and finish honed to the proper surface for the type of rings you are going to be using.  Honing is not a generic process.  To properly hone a block you should use a Torque Plate (see below) to make sure the final bore will remain round when the heads are bolted on.  Final bore clearance is set during the honing stage so your choice in pistons must be made before you hone as well, not just the final bore size but also the type of material in you piston (Hypereutectic, cast, or Forged) and the type of piston skirt must be known.  The other critical piece of information you must have before you hone the block is the type of rings you will be using (cast, molly, chrome, etc.).  Each type of ring requires a different finish on the bore or the ring will not seat properly. 

(Picture of honing in process on a 5.4l Ford Modular block)

Torque Plate:

The purpose of a torque plate it to put the same stress on the engine block it will see when the heads are bolted on.  It has been found that without a torque plate you will actually end up with an oval or stretched bore when the heads are on.  This results in dropped power and reduced reliability.  DG Motors believes so strongly in torque plating that (as of this writing) we are the only shop in the state of Minnesota that has torque plates for the 4.6l and 5.4l Ford Modular motors.

(Picture of same block, close up of torque plate) 

Block de-burring/stress relieving:

When an engine block is cast it ends up with many sharp edges.  A sharp edge on a the block can result in a stress crack.  De-burring a block can be a time consuming process but is a very worthwhile step in the engine building process.  A block that has been de-burred will be much stronger and last longer.

(Picture shows a block that has been de-burred on the front face)

Block o-ring:

Your engine will make power by developing cylinder pressure.  It is this pressure that "pushes" the piston and spins the crankshaft.  When you start to develop excess cylinder pressure (Blower, Turbo, or Nitrous) you will put excess stress on the head gasket.  This often results in a blown headgasket.  Although not the end of the world, nobody likes to have to tear down the motor to install new headgaskets!  By machining a round groove around the cylinder bore and inserting a special wire you will create a stronger barrier for the cylinder pressure and head gasket life will be greatly improved.  You will see that many people will put the o-ring in the head rather than the block, this is typically because the head can be o-ringed without removing the block.  The fact is the head is more likely to warp in the future and require re-machining of this groove and will not result in as strong a seal.  Although it may be tempting it is not recommended to run both!  The problem is a small amount of movement in the head when it is bolted to the engine will result in the wire circles not lining up perfectly.  This will result in a worse seal than if no o-ring had been installed at all!

Blueprinting:

Everyone has heard the term "blueprinting" before right?  Do you know what it means?  Blueprinting is simply the process of checking each of the tolerances of the engine and documenting what the results where.  When an engine has been blueprinted you will have documented proof of each clearance rather than typical machining where the part is machined to the proper size and the final tolerance or clearance is assumed.  Blueprinting is simply documenting your engine build!