PedalToMetal

I've been hearing alot about blueprinting and balancing, what is the procedure, what does it do and how does it help?

Apeiron

Blueprinting is the process of taking a stock block with its loose tolerances and machining it to exact dimensions.

Balancing is the process of weight-matching the reciprocating parts, spinning the crankshaft with bob weights attached to find any imbalance and vibration, and correcting the imbalance by adding or removing weight from the crankshaft counterweights until it spins freely.

Neither of those is a do-it-yourself operation.

spanners

you can do most of the balancing yourself to save money you have to get each piston with its rings and gudgeon pin weigh them to find the lowest weight then carefully remove piston material from the inside of the pistons till they all weigh the same weight to a point of a gram them do the same with the small ends of the conrods and the bigends get all weighing the same.this takes a bit of fabrication of a support for the end you are not weighing to pivot around and you put the other end on the scales once the smallends weigh the same do the same for the bigends with caps on and bearings in then you will have conrods and pistons all weighing the same this is what costs the most when balancing an engine and I do all mine at home first then just tell the engine shop what weights ive calculated for each peice and they balance the crank costs so much less than them spending the hours weighing it all.they will need too know piston weights and bigend and smallend weights

Apeiron

Yes, you can do the weight matching yourself. Most of the time for a rebuild with aftermarket parts you can just buy weight matched sets of rods and pistons.

Sonix

iTrader: (1)

The blueprinting is mostly having all the tolerances measured and set to "some" standard. Everyone has a different opinion on what's "right", but if you've got everything that can be measured, measured and tweaked to where you want it - then you can say it's blue printed. Some people might blueprint an engine to 1969 Chev 302 specs for example.

Typical ones there are piston deck height, rod and main oil clearances, thrust clearance, cylinder head volume, piston head volume, ring gap, etc.
Most of these you can measure at home with a few cheap tools, but most you need a machine shop to modify.

WhiteHawk

Making sure all critical tolerances are at the ideal limits (ex. bearing clearance tolerance is .0015" - .0025", you set them at .0015" because the wear will always make it bigger).

I was taught to do this "blueprint" method in engines class for any engine rebuild as a normal process, so I could never think of building an engine without checking clearances...I suppose less fortunate people just slap her together, eh? I mean, even plastic gage is super easy, why would you not do it?

Apeiron

That's not even blueprinting, it's just due dilligence.

Sonix

iTrader: (1)

Where would you draw the line between normal engine assembly clearance checking and blueprinting Apeiron ?

Apeiron

Checking clearances, measuring the block and machining to correct wear is one thing, but blueprinting is more to do with correcting for variations in manufacturing tolerances in the block. Blueprinting could involve zero decking and parallel decking the block, correcting spacing and alignment of cylinder and lifter bores, correcting crank to cam centerline distance, and all sorts of other things that aren't normally done as part of a routine rebuild.

Sonix

iTrader: (1)

Ah, ok. That's pretty **** retentive stuff there... Whatever helps you sleep at night I guess.

Apeiron

In practice, the term has come to mean very little. All sorts of people will tell you about their "balanced and blueprinted" engine, without having a clue what that means, let alone to what specs the engine was blueprinted to. It's not as tedious though as people talking about their "built" engine... every engine is "built", unless you've got a cardboard box full of loose parts sitting under the hood.

ede

blue printing is a term sort of like 3/4 race cam in that it's undefined. to me a blueprinted engine is assemble to a set of specs not tollarances. checking clearances and measurements isn't the same as blueprinting and if you're using plasti gage to do it you aren't doing a very good job of checking clearances. blueprinting would be settting the piston/deck clearance the saem by machine work, squaring the deck to the CL of the crank, setting end gaps the same, and every variable associated with an engine assembly.