Although it is a normal part of blue printing to check bearing clearances, it is
especially important when freshening up a previously blue printed engine.
Even though you may be replacing bearings with the same mfg. and part
number, that does not mean you will have the same clearance. I have seen
as much as .0005 difference with same brand same number and as much as
full .001 when changing brands.
If that is not scary enough, just another cycle on fasteners can tighten up
clearance by .0002.
A little more clearance may not hurt but if an engine was on the tight side it
could be catastrophic.
As with good cleaning procedures before assembling and engine, blue
printing is very important to having a sound, reliable and great performing
piece when you are done.
Blueprinting is more than recording sizes and relating clearances of the
internal parts. It is the written plan of the clearances you wish for your
application and the adjustment made to achieve them.
Pistons are measured and the block bored and honed to the specification
that the manufacturer suggests'
Piston pin bores are sized to the pins.
Small ends of rods sized to spec for proper press fit or float.
Big ends of rods and main housing bore of block are sized to achieve proper
crush on bearings.
Crankshaft is ground to spec to acquire the desired bearing clearances.
Rings and ring lands in pistons are checked for manufacturers clearance.
Ring gaps are checked and filed if necessary.
All rotating and reciprocating parts are weighed and balanced.
Unless all parts were previously used, Crank throws and counterbalances
checked for interference to block and piston skirts. Rods the same with full
rotation to clear cam lobes, cylinders and pan rails.
Stroke, rod length, compression distance and deck height.
In some instances a double roller timing chain can touch the block, fuel
pump rod or timing cover.
The camshaft must be degreed in and checked to manufacturers
specification, on both intake and exhaust lobe and also on both banks.
Cylinder heads have many things to check, valve margins, stem to guide
clearance, retainer to seal clearance, open and closed pressure on valve
springs, verifying that the springs have enough travel to accommodate the lift
of the cam, checking valve spring outer OD and inner ID for interference with
the spring pocket and valve seal, stem heights equalized when using a non
adjustable valve train and combustion chamber cc's.
Lastly a trial assembly to check valve to piston clearance and with dome
pistons, dome to combustion chamber, then the intake manifold for port
I am sure I have left out several things but the idea is to check EVERYTHING
and not take anything for granted.
One of my engine building customers says it best; Parts that have not seen
each other before have to be introduced to each other or they might not like
each other and have a horrendous disagreement.
With the exception of a break in lube for new cams.
Only use an additive for break-in if no break-in oil is available
It does not take many words for me to tell you what I think about them.
I DON'T LIKE THEM for the most part the term 'Snake Oil' comes to mind.
and do a search on your favorite additive
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