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Technical question regarding 440 6-pack engine balancing...
#2401248
11/10/17 02:28 AM
11/10/17 02:28 AM
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Joined: May 2005
Posts: 581 Texas
Texican
OP
mopar
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OP
mopar
Joined: May 2005
Posts: 581
Texas
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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
Last edited by sunroof_charger; 11/10/17 02:31 AM.
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Re: Technical question regarding 440 6-pack engine balancing...
[Re: AndyF]
#2401423
11/10/17 03:36 PM
11/10/17 03:36 PM
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Joined: May 2005
Posts: 1,959 Apollo, PA.
B1MAXX
top fuel
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top fuel
Joined: May 2005
Posts: 1,959
Apollo, PA.
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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).
Last edited by B1MAXX; 11/11/17 12:30 PM.
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Re: Technical question regarding 440 6-pack engine balancing...
[Re: AndyF]
#2401627
11/10/17 10:44 PM
11/10/17 10:44 PM
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Joined: May 2005
Posts: 581 Texas
Texican
OP
mopar
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OP
mopar
Joined: May 2005
Posts: 581
Texas
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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 ~
Last edited by sunroof_charger; 11/10/17 10:45 PM.
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Re: Technical question regarding 440 6-pack engine balancing...
[Re: Texican]
#2401884
11/11/17 01:40 PM
11/11/17 01:40 PM
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Joined: Feb 2008
Posts: 714 Central TEXAS!!!!
sr4440
super stock
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super stock
Joined: Feb 2008
Posts: 714
Central TEXAS!!!!
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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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