The final balance was performed with my flywheel installed.

I'm not the world's expert at engine balancing, but the process has to do with weight maching all the pistons. Then weight matching all the rods. Straighening and spin balancing the crank. Then balancing all the rods, big end to little end. There's bob-weighting involved and all that jazz.

Point blank, the entire assembly was balanced, then the crank was re-checked with my flywheel and harmonic balancer installed. I don't know if any further adjustment was made to the flywheel.

When I asked my engine builder if I'd need to completely re-balance my engine if I got a new flywheel, his statement was that he's replaced flywheels in the past and 80% of the time he's seen absolutely no issue. But he has had instances where the addition of a different flywheel to the system has upset the engine.

I don't know squat...I'm simply identifying one possible downside to purchasing an engine versus having one built.

I don't know. I didn't balance the silly thing. My point was that the system was fully balanced and stabilized before he tossed the flywheel and harmonic balancer on to make sure everything was still cool. The flywheel WAS used and it was used at the very end of the procedure. As a check. And final adjustments were done based on the flywheel as part of the complete system.

I fully accept that an engine can be balanced without a flywheel, the flywheel be added later, and everything be cool.

But it must also be accepted that balancing an engine WITH the flywheel is not a bad thing. Probably not critical, but definitely not a terrible thing to do...that was my point.

 

I appreciate all the input. The engine I have now WAS originally (well, not ORIGINALLY I suppose) a fleabay motor. It has dealt with my heavy foot up to 5500rpm shifts and cruising miles in between. However, it was done when I was young(er) and foolish and don't know who it was from or what is INSIDE it. She runs fine but I was her to moooove, like somewhere in the 12s.

 

Keith,

Back in the early 90's I worked in an engine machine shop for a couple years while I was going to college. I've balanced a good number of rotating assemblies.

Internally balanced engines require a neutral balanced flywheel and harmonic balancer. This means that they each must be balanced separately from everything else. The rotating assembly must also be balanced by itself.

If the rotating assembly along with the flywheel and/or the harmonic balancer are balanced together, you've now created a "set". No parts in this set can be replaced without possibly upsetting the balance.

Now, if everything is balanced separately, and have a good neutral balance, the flywheel, the harmonic balancer and even the rotating assembly could be replaced and as long as each part has a good neutral balance, the overall balance won't be affected.

If your engine builder only assembled everything together to check it, you're fine. If he made any adjustments while it was all assembled, there's no guarantee that the flywheel or harmonic balancer can be replaced without upsetting the balance. If he's only getting an 80% success rate with replacing flywheels, this makes me think that he's making changes while it's all assembled.

 

Good machine shops won't do this.

 

I didn't go to a machine shop. I went to an engine builder who has been doing it since he was 5.

Yet again, I find myself mired in a pointless discussion. I freely admit that my original statement regarding the need to balance the engine with the flywheel as part of the 'system' may have been an overstatement with my inexperience to blame.

That does not mean that it is a bad thing to 'back check' the system with the flywheel installed.

That does not mean (as you suggest) that I did not go to a good "machine shop".

And that does not mean that this engine may be fine if not pushed really hard, but for the money, I have serious questions about the care used in assembly, the choices of components, and the durability of the engine when stressed.

I have already said that I stand corrected. Please focus on the OP and his questions. Please.

 

Pointless? You make posts about subjects you know nothing about and when you're corrected it's pointless?

 

Nothing. No merit.

Out of all I said and all the time I took responding to the OP, this is where I'm at. Shouldn't have bothered, huh? This one thing where we have a difference of opinion.

Ok, God of all. It's your darn forum. Have fun with it.

I am now officially on a break.

To the OP: my apologies. I only know a little about a lot. My comments were sincere and intended to lend perspective. Whichever way you go, I'm sure it will be the right call. Have an awesome time. Save the wave.

OK...NOW I am officially on a break.

 

How about this guy? I have an edelbrock rpm air gap intake and 750 carb to go with it.

http://kansascity.craigslist.org/pts/4517024170.html

 

Why what advantage will they serve on a 40 year old street car? That cool piston slap sound? As usual all the talk about cheap cast vs forged and how its needed comes in before anyone even bothers to ask what the cars for? Hyper pistons have advantages in a street engine and the stock l48 was made of cast components. Cast components are realistically fine for builds under 500hp.
Is this for Drag racing or is it a street cruiser? Or both? Are you planning on changing your gearing to make use of a big cam and forged internals? If you plan on running high rpms over 5500 balancing is a must for longevity.
Just my 2 cents.

Feeling daring?
http://buffalo.craigslist.org/pts/4526192885.html

 

Pretty cheap or too cheap. If you jumped on it, the first thing I would do(or have done if you can't) is pull it down and check everything. It might be fine or not? These types of deals have a way of biting you in the butt.

Go with a trusted source that offers a decent warranty, and mostly you can't go wrong.