Lichtmann

Hi
I got a '58 371 rocket engine.
The rubber between harmonic balancer and pulley is dried out.
So i got a new one.

I don't know much about balancing so here comes my question.
It was my understanding that the early olds rockets are externally balanced. Meaning that flywheel, flexplate, crank AND pulley/ balancer were balanced as one assembly.

Is that right and i have to transfer the maybe existing unbalance of the old to the new one?
Or is it neutral and just an easy swap?

I don't have the center bolt size handy. And the engine is stored far away. Can you give me a quick recommendation which balancer install tool to buy.

best
Thomas

67 Cutlass Freak

Thomas, I have a 394 here which is in the same engine family. The balancer bolt is 1 1/8". They are very hard to remove. My 1/2" drive impact gun would not do it. I had to use a 3/4" impact gun. You could try the old trick with a breaker bar and use the starter. The balancer is also hard to remove. I used a heavy duty Snap on 3 jaw puller. There's no easy way to do it. These engines are externally balanced, so the only way to do it correctly would be to disassemble the engine and have a machine shop balance the rotating assembly for you.

By the way this is considered a Big Block engine.

Lichtmann

67 Cutlass Freak, Thanks!

Next time i'll go to big blocks!
The pulley is already off. My machine shop did that for me. How they did it? No idea
Question aims for an installation tool. 1-1/8" is head or thread size? My memory says head.

The manual says torque center bolt to 100 lbs ft MINIMUM.
??? Funny people. What about maximum?

I was afraight of this answer.
The engine is already assembled.
Question now is how bad can it be installing an other balancer.
Got this one from Ross Racing Engines. Tony told me it is balanced correctly.
Everything i know is that Tony knows what he's doing.
But i want to understand. So please take me by the hand and lead me through balancing land

The following was done to the rotating assembly:
Crank has been polished. Not ground. Standart size bearings.
Rods are stock.
Got a new piston and ring set from EGGE. Standart pistons .030 oversize. No fancy stuff.
Cylinders bored and honed.
Original jetaway transmission with standart converter, flywheel and flexplate.
And now a new pulley/ balancer.

As you can see there are no major changes. Wanted to keep everything bone stock. It's supposed to be an original late 50s driver engine. No rpm or torque monster.

Again. I'm not a mechanic. And this is my first engine rebuild. The shop did the most of the work for me cause i didn't dare. I'm learning a lot. Most of the time how you don't do it
If i'd known about this whole internally/ externally balancing thing before i shure had it done. Cause it's the only way to do it right.
But now I don't want to tear it down once again. I got too much time and money in it already.

Any soothing words?

67 Cutlass Freak

I think you will be just fine. You said it yourself, " No rpm or torque monster". These motors are pretty powerful torque beasts in stock form. I was not alive, but my dad told me, back in the fifties all the hot rodders would seek out these Olds engines for their Chevys or what ever they had. Good luck with your project. You should start a build thread and post a lot of pictures. Everyone loves the photos.

Olds Dad

I strongly recommend you talk to Tony since he built the engine. I know these were externally balanced when new, but I also know that Tony balances them internally when he gets his hands on them (at least he has according to many other posts I've read on this and other forums) - so since he built that engine he is the one you need to talk to. If it is still 'stock' (i.e. 'externally' balanced) you'll need the correct flywheel and harmonic balancer - if it's been 'internally' balanced, your options are different.

67 Cutlass Freak

I didn't read that Tony built this engine. I was under the impression that the balancer was purchased from Tony. The original poster, Lichtmann, is from Germany. I just assumed the engine was being built locally since he stated it was a couple hours from his house.

Lichtmann

Please excuse my maybe confusing expression.
But 67 Cutlass Freak is right. The engine was rebuild here in germany.
Only thing i got from Tony was the balancer and a set of head bolts.
I asked him about the balacing of the dampner and he told me "it is balanced correctly".
This confused me because of the whole internally/ externally discussion.

Didn't want to annoy him with school boy questions. So i thought it's a good idea to gain some knowledge before i ask again.
But he also knows that i'm not building for high rpm.
I don't doubt his answer. Just want to understand cause it doesn't match my current state of knowledge.

Olds Dad

My mistake - I misunderstood.

Lichtmann

Olds Dad, no problem. But whats your assessment to this?

D. Yaros

Would it not be the wise thing to do to have the original harmonic balancer rebuilt?

Octania

Thomas, I have a 394 here which is in the same engine family. The balancer bolt is 1 1/8". They are very hard to remove. My 1/2" drive impact gun would not do it. I had to use a 3/4" impact gun. You could try the old trick with a breaker bar and use the starter. The balancer is also hard to remove. I used a heavy duty Snap on 3 jaw puller. There's no easy way to do it. These engines are externally balanced, so the only way to do it correctly would be to disassemble the engine and have a machine shop balance the rotating assembly for you.

================================
I would say any other similar balancer will be close enough. Sure, if it's all apart for rework, or at the initial assembly, they might drill little teensy spots out of the balancer to get that last bit of correct balance... but it's not something I would dismantle the engine over. Check new vs removed balancer and if the weights are about the same, call it close enough.

The bolts are 3/4 fine thread, the TOOL size is 1-1/8"
They are "as tight as you can get" with 100 min being a bit low I feel. 250+ is specified in later manuals.

here is your EASY puller
I bought a $50 Harbor Fright [sic] one and made an adapter for Olds 350/455 balancer out of a used pulley, to hold the bolts just right. Works like magic.

http://cgi.ebay.com/ebaymotors/PRO-1...item2c70148787

http://www.harborfreight.com/5-ton-t...ler-95326.html

D. Yaros

From what I am reading, am I to understand that for each and every Olds coming down the line at the factory some process was undertaken to determine the correct weight of the harmonic balancer to be installed and then steps taken to make sure the harmonic balancer installed weight was in accord with the individual calculation?

That seems like a time consuming and labor intensive process that I cannot see GM/Oldsmobile undertaking? But then, what do I know?

I wonder if there is anyone here who was there at the time who could fill us all in on what was/was not done in this regard?

Tedd Thompson

My thoughts on this is the balancers were all the same but on engines that are externally balanced the flexplate was adjusted by adding a weight to it. You want the flexplate that came with that engine or re balance everything at the machine shop if you are going to mix and match. The very best thing would be to give Tony a call and remove all doubts before you go any farther....Just my thoughts....Tedd