What would you choose? Here is my opinion. I know internal costs a little more and probably is the better choice, but what if you bought, say, the Eagle stroker kit with the balanced flexplate and balancer, would that still be a good deal? My thought is, if I were going to sell my car and I told a potential buyer that it has a 383 stroker in it, if it was internally balanced, there would be no proof, unless a teardown. Now, if it is externally balanced, you could show them the balancer and if he/she knows what their looking at, that should be a comfort knowing it could very well be a stroker engine. Which way to go???

 

Internal is the only way I would go.

 

If it's internally balanced, the flex plate won't have any weights. Externally balanced will.

Spend the few extra $ and go internal

 

External is fine for a truck engine or something that's never really going to see anything over 5K RPM...but for anything that's going to see performance use internal is worth the money.

Agreed that anyone can look at the balancer and flexplate/flywheel and tell if it's external.

 

Keep receipts as proof of the build components to show future buyers.

 

I can't see how external balancing suddenly is such an issue when doing a 383 vs a regular higher hp 350 engine.

Could someone educate me on this subject?

 

if it is externally balanced

My first thoughts are the person is ignorant, cheap, or stupid!

 

Why? Why is external balancing not a problem on a 400hp YearOne crate which everyone deems a great engine and it is on a same hp stroker engine?

Technically I don't see it; balanced is balanced or not?

 

Rotating weight. Heavy Damper and heavy crank with mallory weights welded in. Like somebody stated, made for lower rpm truck motors.

Yes, the cheap crowd likes a 400 hp Year one crate motor. It is also easy to pick up a 300 lbs chick at the bar

 

When people started building 383's they were pretty much all externally balanced, and they ran great.
They were also mostly built with the short 400 connecting rods that everyone says you shouldnt use.
And they still spun up way beyond 5000 rpm all the time.
While internally balancing is better, an externally balanced engine is far from a ticking time bomb.

 

The way I see it there are many choices made when building an engine. If rpm is kept under 5500 and HP is at or under 1 HP per CI then many economical choices can be made that save a lot of $$$$. As power levels rise and RPM capability these choices go off the board. You can build a 383 for $2000 or $10,000. If I am building either I am going internally balanced. Do what you want.
This same type of discussion happens with heads, AFR vs ProComp, Cranks, Scat 9000 Vs Callies Dragonslayer, Rods Scat vs Oliver, Main bearing caps, 2 bolt stock vs 4 bolt billet splayed. Pistons, cast vs hyper vs low expantion forged vs forged. There are also choices between the high and low priced options and for some uses the low priced option is better for the intended use. Don't want to run cast pistons with your 500 HP small block with nitrous, Don't want to run regular forged pistons in your 200 HP low compression 350. You hear all the time "My buddy runs scat 9000 crank in his 600 HP big block and shifts at 7000 RPM with no problem" or "a 2 bolt block is fine up to 450 HP" This may be true but for how long and at what cost if there is a failure. Same is true with internal vs external balancing. Internal is better. Harmonics are very damaging to engine internals and internally balanced engines have greatly reduced harmonic vibration for better long term dependabilty and longevity.
Reciepts for the work done and parts chosen are your best assurance to a buyer that the engine was built to compliment the power level and useage.

 

Well, in a word - no I'm probably going to get some flames for walking through this with all the nitpickers around here, but here goes

The rotating ***'y consists of some very heavy things on a crank throw (pistons+rings+rods+bearings+oil) that are counterbalanced by the counterweights opposite the throw. The amount of weight the counterweight is intended to counter is the "bobweight".

If the stuff attached to the crank throw is significantly lighter or heavier than what the counterweight is intended for, the crank will experience a harmonic, a rythmic vibration like a tuning fork. Going further, if the weight on one throw is different than another, the same situation will occur.

To rectify an out of balance, there are a couple of options that can be used individually or together:

1. Modify the counterweight either by profiling/drilling holes (lighter) or pressing in slugs of Mallory metal (heavier...and expen$ive).

2. Modify the bobweight by lightening pistons, rods, etc. Even better, match all of the bobweights precisely.

3. Add extra counterweights at either end of the crank.

Internal balancing uses #1 and #2, external uses #3. It's easy to see where #3 is an engineering short-cut; the harmonic will still be there, but we're dampening it out to some extent with weights on the ends. But the weight is on either end of the crank, not opposite each throw...and this sets up it's own harmonic.

Stealing from "Hitchhiker's Guide to the Galaxy", the practical upshot of all this is that as RPM increases the harmonic worsens and starts beating the heck out of the front/rear main bearings and sooner or later breaks the crank. I've seen abused external balance 383's and the bearings do tell the tale. I have personally never seen a broken external-balance 383 crank...and I have seen some folks run the heck out of them.

But as DRIVESHAFT said plainly and I noted earlier, an external balance isn't a bad engine. It's just intended for a different purpose and so has different operating rules.

<Nomex ON>

 

Very well said

I live on the cheap side of that street myself

 

I internally balance all my stroker engines I use forged rotators and I use 6.000 rods which will give you more counter weight to internally balance, plus a lighter pistons, less side loading with long rod or better rod ratio and one other important reason with a short rod stroker there is more piston hanging out of the bore at BDC which I feel is a concern.

Also if the flywheel needs to be turned on an neutral flywheel it can be rebalanced compared to an extrernally balanced flywheel. Plus once the flywheel is balanced you can put on the pressure plate and dial that in as well. Can't be done with an interanlly balanced set up.

Also do a search on broken crank snouts I am sure 95% or better are externally balanced set ups.

Having an out of weight balancer on the front of the crank is asking for trouble. I have heard about this problem to many times.

 

Dont you think that statement is just a bit extreme?
Chevrolet has been selling engines with "out of weight" balancers on them for over 40 years, and they still come with a 2 year warranty.

Once again, I agree internal is better, but that doesnt mean that anything else is garbage.

 

IMO if you are planning mild street engine that will rarely see 6000 external is fine. If you are planning on a max effort engine, everything must be meticulasly assembled and therefor internally balanced.

 

What SBC has GM been selling for 40 years with out of weight balancers???

Could you quote who said anything else is garbage as I can't find that post!!!!

If your building a 383 out of your 350 chances are you can use your balancer and flywheel you already have and not have to spend extra money on a new flywheel and balancer

 

(1) I didn't really see anyone in particular say everything else is junk!

(2) 400CI GM's Assuming this poster meant external balanced dampeners.

 

take a picture of your engine with a ruler in cylinder #1 at bottom dead center to show its stroke.. then show that pic to your potential buyer to prove what the stroke is..

 

Don't understand why this subject gets so out of hand but it does. The Truth of this internal external argument is that there is really two reasons why internal balance is better!

(1) is the ease of replacing clutches and such and still be able to balance them to work in the engine and the cost savings in some cases in not buying external balance parts, though the added cost of internal balancing may off set this some.

(2) is the additional dollars a shop gets for this work and for some people to have another BENCH racing thing to talk about!!