easy balancing Q - Moparts Forums

Register Log In Moparts Forums Unlawfl's Race & Engine Tech easy balancing Q

Print Thread

easy balancing Q #2573319 11/03/18 03:26 AM 11/03/18 03:26 AM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert OP Circle Track
RapidRobert OP Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	balanced 360 short block. If I drill some notches in the pistons thereby lightening em is it now under balanced or over balanced? (I understand that over is OK (within reason). With alum weighing 2.7 grams per CC & the notches at an 18 deg angle & .030" to .050" deep it wouldn't be alot & I for sure ain't got the math skills to nail it dead on for grams but I am curious. Thank you for your time. live every 24 hour block of time like it's your last day on earth

Re: easy balancing Q [Re: RapidRobert] #2573409 11/03/18 12:22 PM 11/03/18 12:22 PM
Joined: May 2005 Posts: 1,959 Apollo, PA. B1MAXX top fuel
B1MAXX top fuel Joined: May 2005 Posts: 1,959 Apollo, PA.	This is the way I look at it, you weigh up a bob weight, get you number then add a % of over balance and then balance the crankshaft to that number. So in my view you are removing from the bobweight and adding over balance to the crankshaft. You didn't say what kind of components are being used here so I will use 2300gr ballpark for a typical 360 and you will remove 2gr of material per so 4/2300= .0017 or less than 2 tenths of 1%. cut away

Re: easy balancing Q [Re: RapidRobert] #2573425 11/03/18 01:03 PM 11/03/18 01:03 PM
Joined: Mar 2010 Posts: 1,061 Atlanta, GA M mgoblue9798 super stock
mgoblue9798 super stock M Joined: Mar 2010 Posts: 1,061 Atlanta, GA	You could change the balance by that much by using stp in the engine. I wouldn't be worried about it in a street engine.

Re: easy balancing Q [Re: RapidRobert] #2573479 11/03/18 03:09 PM 11/03/18 03:09 PM
Joined: Jul 2009 Posts: 490 IL E EchoSixMike mopar
EchoSixMike mopar E Joined: Jul 2009 Posts: 490 IL	Why are you drilling aluminum? Stress risers=cracking is significant issue with aluminum. S/F....Ken M

Re: easy balancing Q [Re: EchoSixMike] #2573609 11/03/18 09:25 PM 11/03/18 09:25 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert OP Circle Track
RapidRobert OP Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Ken what is going on is I need more P/V clearance so I had to do it. My crank man gave me a (gram) # & I filled the notches with clay then dropped one of em into a burette & noted the CC rise then that # times 2.7 to get grams & as he said I am way under the limit but someone just mentioned that overbalancing is better than under so this is more of a curiosity question than an actual dilemma, that if I lighten a balanced assy (like I did) am I over or under balanceing... live every 24 hour block of time like it's your last day on earth

Re: easy balancing Q [Re: RapidRobert] #2573804 11/04/18 11:25 AM 11/04/18 11:25 AM
Joined: May 2005 Posts: 1,959 Apollo, PA. B1MAXX top fuel
B1MAXX top fuel Joined: May 2005 Posts: 1,959 Apollo, PA.	Originally Posted By RapidRobert Ken what is going on is I need more P/V clearance so I had to do it. My crank man gave me a (gram) # & I filled the notches with clay then dropped one of em into a burette & noted the CC rise then that # times 2.7 to get grams & as he said I am way under the limit but someone just mentioned that overbalancing is better than under so this is more of a curiosity question than an actual dilemma, that if I lighten a balanced assy (like I did) am I over or under balanceing... you are moving it slightly over...depending on where you began at. Last edited by B1MAXX; 11/04/18 11:30 AM.

Re: easy balancing Q [Re: RapidRobert] #2573895 11/04/18 03:10 PM 11/04/18 03:10 PM
Joined: Jan 2003 Posts: 1,908 Nebraska 4 4406bbl top fuel
4406bbl top fuel 4 Joined: Jan 2003 Posts: 1,908 Nebraska	Your crank will be overbalanced, but remember you only add 1/2 the piston weight anyway so not by much.

Re: easy balancing Q [Re: RapidRobert] #2573970 11/04/18 05:19 PM 11/04/18 05:19 PM
Joined: Aug 2003 Posts: 1,313 Charlotte, NC L LSP pro stock
LSP pro stock L Joined: Aug 2003 Posts: 1,313 Charlotte, NC	Notch away, very insignificant effect on balance. There's oil flying around changing what is perceived as balance anyway, especially at the rear of the motor in some cases when you accelerate.

Re: easy balancing Q [Re: 4406bbl] #2574058 11/04/18 08:19 PM 11/04/18 08:19 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert OP Circle Track
RapidRobert OP Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Quote: Your crank will be overbalanced, but remember you only add 1/2 the piston weight anyway so not by much. That is what I needed to know & yes the recip weight is halved. Thank you! live every 24 hour block of time like it's your last day on earth

Re: easy balancing Q [Re: RapidRobert] #2574441 11/05/18 03:30 PM 11/05/18 03:30 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	Cut away. Among all this talk of the "balancing formula" remember that this is empirically (experience)based and not derived from the geometry of the engine, etc. R.

Re: easy balancing Q [Re: dogdays] #2574890 11/06/18 03:46 PM 11/06/18 03:46 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert OP Circle Track
RapidRobert OP Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Hello Dog, its been awhile. All done (& deburred). EDIT My crank man gave me (2) (gram) #'s, one that is getting close to problematic & one that is definitely too much (I got em wrote down somewhere) but he said valve notching wont even get me close to it & he was right I wasn't even close, I was just curious if it was (now) "under" or "over". Last edited by RapidRobert; 11/06/18 08:39 PM. live every 24 hour block of time like it's your last day on earth

Moderated by Al_Alguire, Hotwheelsjr, moparts, not_a_charger, RangerDan440, tboomer

Hop To

Powered by UBB.threads™ PHP Forum Software 7.7.1