Engine Balanceing

I'm planning on building a short block sbc.
At some point I'll have to get the rotating assembly balanced.
Do I have to know anything, give them specs, or do i just drop off at the shop and tell them to balance it?

I know nothing about balancing engines.

Thanks

 

Look on U Tube to see what a balance shop does, that will help you understand the procedure. They will want your flywheel and harmonic balancer along with the rotating assy and pistons.

 

All internal parts, clean or new, pistons off rods, crank, balancer, flywheel, pressure plate. Rings, rod bearings, money.

 

Money well spent!

 

Thanks guys, but the important question remains.
Do I have to supply them some sort of specs as to how I want it balanced, or just drop it all off?

 

They will know what to do.

 

The answer is no and yes. If it meets the criteria listed above they will know what to do and hand you a bill.

 

You need the pistons, pins and rings, rods and rod bearings, crank, balancer and flywheel. They are sweet running engines a balanced up!!

 

If they don't already have the information you are at the wrong shop.

Charlie Stephens

 

if the crank came balanced from scat do you still have to balance the whole assembly or will it run ok the way it is?

 

If you cant eat it you probably dont need it.

 

you can rough balance a motor like the OEms do , but with a new crank to make a motor run better its best to have the whole assy redone if a major component was replaced as its balanced as a group , if your builder has the old build sheet thye can sometimes just machine the crank to make it match the numbers .

 

If it's scat have it balanced. The last one I got was a 350 crank with 400 mains it needed balanced and turned.

 

What they will do is make all of the pistons and rods the same weight. Then they will spin the crankshaft to balance it. Then they install the harmonic damper and balance it. If you know what belt pulleys you are using they can check those too. Next they install the flywheel and balance that. Then install the pressure plate and balance it. Finally, they will balance the clutch disc on a separate shaft. They will mark everything so it is installed in the correct position.

Some engines, like the 400 Chevy, have a crankshaft that can't be balanced by itself. It has to be balanced with the damper and flywheel or flexplate installed. The damper and flexplate are made with extra weight to counter the imbalance in the crankshaft. Some shops will try to cut corners and balance every engine like an externally balanced engine because it saves them a couple of steps to balance the damper and flywheel separately.

 

You can take all that to the bank.

"Been balancing stuff for 60 years"