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#2401248 - 11/09/17 11:28 PM Technical question regarding 440 6-pack engine balancing...
sunroof_charger Offline
mopar

Registered: 05/03/05
Posts: 465
Loc: South
I'm going to try very hard to describe my situation and questions very carefully so please be patient with my ignorance....

I have a 440 (1970 block) fresh rebuild and assembly that is ready to install.
It is completely assembled from pan to intake, etc...ready to drop in.

I bought a 1970 Charger R/T and the 1970 Block, Steel Crankshaft, 6-Pack Rods and Harmonic balancer came with the car... I DO NOT KNOW IF THEY WERE PREVIOUSLY BALANCED OR IF THEY CAME FROM THE SAME ENGINE.

I sent the engine off to a machine shop to be cleaned, machined and assembled. I DID NOT ASK THEM TO BALANCE IT - MY MISTAKE.

As I was preparing the front of the engine for the pulleys/brackets, etc..a good friend and great Mopar mechanic asked to see my harmonic balancer and when he saw that it was a 6-pack balancer he asked if this engine had 6-pack rods and I said YES it does and he verified the the casting number on the rods and agreed that it did have 6-pack rods and I had the right harmonic balancer.

He also asked if I had the rotating assembly balanced and I said NO, I did not know I needed to (again, my mistake I know).

He said that I may have problems with vibration if I install this balancer on this engine without balancing and that got me to thinking:

I called my machinist, explained my situation and asked him if new Hypereutectic pistons are all pretty close to the same weight when ordered new and he said yes they are very very close.

Question: Is there any way I can get by without completely disassembling the engine and having it balanced ?

If the new Hyper-Pistons are very closely the same weight and I use a 6-pack balancer, will the engine run with serious vibration or do I need to have it all balanced ?

Can I use a regular balancer without the offset counter weight ?

Are there any alternative options besides having it balanced ?

Thank You Very Much
Mike




Edited by sunroof_charger (11/09/17 11:31 PM)

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#2401252 - 11/09/17 11:41 PM Re: Technical question regarding 440 6-pack engine balancing... [Re: sunroof_charger]
calrobb2000 Offline
pro stock

Registered: 01/20/03
Posts: 1455
Loc: s. e. pa.
hi

6 bbl engines also require correct ofset ballanced flywheel or converter OR special flexplate !

even if the pistons all weight the same and they are a different weight than stock they will upset the balance !

geet er done !

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#2401257 - 11/10/17 12:08 AM Re: Technical question regarding 440 6-pack engine balancing... [Re: sunroof_charger]
AndyF Offline
Too Many Posts

Registered: 01/20/03
Posts: 23235
Loc: Oregon
If your machinist kept good notes you might be able to figure it out. What you need to do is figure out if your new pistons + pins + rings are close to the same weight as the original parts. If they are then you should be close enough for a production tolerances. You will need the matching flywheel or flexplate to mate up with your damper.

If the piston + pin + ring weight is significantly different than the factory weights then you'll need to pull it back apart and get it balanced.

The factory had fairly loose specs on balancing so if you are okay with factory specs you have some wiggle room.

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#2401423 - 11/10/17 12:36 PM Re: Technical question regarding 440 6-pack engine balancing... [Re: AndyF]
B1MAXX Offline
mopar

Registered: 05/07/05
Posts: 677
Loc: Apollo, PA.
If the hypereutectics were not factored into the balance bob weight and the balance job was factored with the stock cast piston (stock balance job) It will need to be re-done. there is a significant difference between the two. close to 100 grams (per piston).


Edited by B1MAXX (11/11/17 09:30 AM)

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#2401483 - 11/10/17 02:27 PM Re: Technical question regarding 440 6-pack engine balancing... [Re: sunroof_charger]
AndyF Offline
Too Many Posts

Registered: 01/20/03
Posts: 23235
Loc: Oregon
Yes that is probably true but it could still be in spec. It might vibrate at certain speeds. It would be overbalanced which is what some engine builders prefer on engines. All depends on how the guy is going to use this engine and what his tolerance is for some vibration. Engine builders over balance 1 or 2 percent and a 440+6 is a heavy bobweight, maybe close to 3000 grams............

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#2401627 - 11/10/17 07:44 PM Re: Technical question regarding 440 6-pack engine balancing... [Re: AndyF]
sunroof_charger Offline
mopar

Registered: 05/03/05
Posts: 465
Loc: South
Thanks for all of the replies.

To my knowledge, all components (Crank, Harmonic Balancer, Flex plate and connecting rods) are stock and unmodified.

The harmonic balancer is a 6-pack balancer with 4 very small holes drilled in one side about 1/4" in diameter and less than 1/16 or 1/8 in depth. This could just be factory balancing, I'm not sure.

The 6-pack harmonic balancer came from the same engine as the steel crank and the 6-pack rods (from a 1970 block). The hyper-t pistons are new and were not drilled or modified. Not sure about the flex plate.

Thanks ~


Edited by sunroof_charger (11/10/17 07:45 PM)

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#2401741 - 11/10/17 11:30 PM Re: Technical question regarding 440 6-pack engine balancing... [Re: sunroof_charger]
BSB67 Offline
master

Registered: 02/19/05
Posts: 3368
Loc: Prospect, PA
But the pistons are likey going to be your issue for balance.
_________________________
500" NA, Eddy head, pump gas, exhaust manifold with 2 1/2 exhaust with tailpipes 4150 lbs with driver, 3.23 gear, stock converter 11.68 @ 120.2 mph

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#2401853 - 11/11/17 09:45 AM Re: Technical question regarding 440 6-pack engine balancing... [Re: AndyF]
B1MAXX Offline
mopar

Registered: 05/07/05
Posts: 677
Loc: Apollo, PA.
Originally Posted By AndyF
Yes that is probably true but it could still be in spec. It might vibrate at certain speeds. It would be overbalanced which is what some engine builders prefer on engines. All depends on how the guy is going to use this engine and what his tolerance is for some vibration. Engine builders over balance 1 or 2 percent and a 440+6 is a heavy bobweight, maybe close to 3000 grams............


I am with you, but....OK so 1-2 percent of 3000 gram bob weight is 30 to 60 g he'll be somewhere around 100 (3.3%). To the OP, keep us tuned in to the decision/results please. thumbs

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#2401884 - 11/11/17 10:40 AM Re: Technical question regarding 440 6-pack engine balancing... [Re: sunroof_charger]
sr4440 Offline
mopar

Registered: 02/06/08
Posts: 412
Loc: Central TEXAS!!!!
you changed a internal component, bite the bullet and pull it apart and get it balanced.

I have had two engines (that i know of) on the dyno that the owners didn't balance. once i felt vibration on the 1st pull, dyno session was over after playing 20 questions.

IMHO if you pull it apart, I would get some aftermarket rods and a balancer. your engine will rev faster and have less stress on the bottom end, lets face it those rods are at least 45 years old.


Joe
_________________________
Without Data, you’re just another guy with an opinion.

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