In terms of engine parts, what do you need to take to the machine shop so they can balance your lower end?

The last time I asked a machine shop guy a simple question like this I was told I needed to visit his shop, check things out, and spend $1300 on a short block. I never really did get an answer.

I'd like a short answer to this one. Thanks a lot.

Static or dynamic balance?
Complete rotating assembly (crank, rods, rod caps, pins, pistons)
Harmonic balancer
Flywheel

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Steve Strasemeier (70SS)

Which type of balancing is better? I assume dynamic? Redline around 6 to 6500 RPM.

A guy told me I'd need an NHRA type of flywheel for this motor. Is that correct?

Thanks for the quick reply, Steve.

TH,
I can't answer you an the NHRA flywheel. I have never seen the tech guys check that on a "street" car at the track.
Send everything Steve mentioned, plus one set of rod bearings and one set of rings (I always just take the boxes of bearings and rings). If you are going to use a 4sp, some people, including myself, take the clutch pressure plate.
In the Okla City area, balancing usually goes for $100-120. That's what I see other people post here also.
The shop I use does a combination of dynamic and static. He's a pro.

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Pretty good description of balancing over on the site www.442.com. Gets complicated. Could be the best 180 bucks spent on an engine. tom

TH,
In order to balance your "motor" you will need to bring the pistons and pins, piston rings, connecting rods, 1 set of rod bearings, the crankshaft, flywheel and harmonic damper.
I do not believe there is such a thing as statically balancing a motor. You can make all the parts the same weight, but they are all usually very close anyway. What is really important is to "balance" the crank to the weight of the rest of the parts.
I will try to give a simple explaination: The first thing done is to make all the pistons the same weight. Then you do the same with the connecting rods, exept you actually have to make all the "big" ends the same, and then all the small ends the same. There is a fixture that is used to weight each end seperately. After doing this, you weigh all the other parts then using a pretty simple formula, you make up a set of special weights that are called "bob" weights. These weights are then clamped on the crankshaft in place of the rods and pistons. Once the weights are on the crank, it is placed in a machine very similar to a tire balancer and spun to a predetermined rpm, usually around 600rpm. The balancing machine then tells you where to subtract or add weight on the crankshaft in order for it to be in balance, just like a tire. Most of the time, in performance applications, you have to remove some weight because the new parts are generally lighter than the original ones. Some motors (454 and 400 for example) require that the damper and flywheel are on the crank while balancing. These are the motors that are considered externally balanced because some of the counterweight is on the flywheel and damper.
This a very simplified description of the procedure. Pictures would tell it much better and I have been working on a balancing section for my web site, but have been too busy to finish it lately.
Hope this helps.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Hmmm...a combination of both. Well, if I get a choice, which should I go with?

I don't even know what this NHRA flywheel is. Can someone clue me in on this thing? Do I REALLY need to invest the money? This guy says it will cost me only a few bucks more than a stock flywheel.

BTW, I don't have a flywheel at all, so the cost difference might not be a big deal. How come I've never heard anyone on this list mention one?

What is an NHRA flywheel? Whatever it is, you don't need it. An ordinary flywheel will do.

TH,
An NHRA (actually SFI) approved flywheel is necessary at many tracks depending on what et your car will run. It is a heavy duty version. Most tracks, both NHRA and IHRA are getting very strict on these rules due to insurance regulations and sanctioning rules. If the tech inspector from your track advised you to use a SFI approved flywheel, I would do it just to save the hassle of having to change it later. They are not that expensive for an automatic trans. Usually in the $100 range.
I would also like to re-emphasize, static balancing the parts of your motor (making all the pistons etc the same) will NOT stop a vibration if those weights are significantly different from the parts that the crank was originally balanced to by GM.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

You might want to check to see if you are looking to buy a "flywheel" or a "Flexplate". Flywheel is used on a manual transmission car and a flexplate is used on an automatic. There is a huge differance between them as you can tell. If you do not know the differance then just ask us here and we will be glad to help. As for a choice of which way to go, go someplace else to get the work done. A pro would not leave you hanging like that, if you tell him static thats what you'll get and you will only be getting 1/3 of the job that you will most likly be paying full price for. As DZ said the entire job should range around $125.00 for a Dynamic balance that always includes static balance of the parts Bill K spoke of.

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CRUISER

Man, thanks to everyone for being so helpful! I just keep wondering what my high school rod would have been like if I'd had all this information available to me. ...I'm sure it would've still been a rustbucket though!

For the record, your information finally enabled my brother and I to settle on a shortblock 350 which we just purchased on Saturday.

Now I have this question about rods...(see topic with same name).

The only time you need an SFI approved flywheel is for cars running 10.99 (1/4 mile)and quicker unless the track rules override this requirement.