Re: Balancing a Hemi question.
[Re: fastmark]
#2115479
07/22/16 01:23 PM
07/22/16 01:23 PM
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crabman173
Unregistered
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crabman173
Unregistered
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Eagle and Scat are very good cranks and have target bob weights published to give you an idea--Light pistons keep you out of the woods when doing a Hemi--It is not uncommon to have several slugs of Mallory in each end if you don't--I balanced a 572 CI last week--Eagle crank--light weight Diamond pistons, H Beam rods and I wound up taking 50 grams plus minus off each end it was a breeze
Our crank was on low side and with Clevites it had plenty of clearance and perfect end play in a brand new Hemi block
My experience with Source cranks is that they tend to be on the low side and always come out with plenty of bearing clearance as well--A Stock 440 steel crank can usually handle up to 2700 plus grams bob weight allowing you to remove a little to get it right--all depends --each crank is a little different Good Luck
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Re: Balancing a Hemi question.
[Re: fastmark]
#2115488
07/22/16 01:37 PM
07/22/16 01:37 PM
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Joined: Feb 2008
Posts: 717
Central TEXAS!!!!
sr4440
super stock
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super stock
Joined: Feb 2008
Posts: 717
Central TEXAS!!!!
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figure your bobweight out, then call Molnar Technologies and have them send you a crank balanced to that weight.
Joe
Without Data, you’re just another guy with an opinion.
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Re: Balancing a Hemi question.
[Re: fastmark]
#2115849
07/22/16 10:17 PM
07/22/16 10:17 PM
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Joined: Oct 2007
Posts: 4,213
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,213
New York
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X3 - too expensive to save money on the crank.
Boffin Emeritus
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Re: Balancing a Hemi question.
[Re: fastmark]
#2116475
07/24/16 03:14 AM
07/24/16 03:14 AM
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Joined: Aug 2003
Posts: 43,368
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,368
Bend,OR USA
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if your building it (a hemi motor) for a customer do you really think he wants to cut corners on this build? If so tell him to go elsewhere  I leaned a long time ago to not take on cheap customers, they cost to much in time and grief   If your trying to save him money what are you going to tell about using a 440 crank in a 426 Hemi  Ohio Crankshaft Company probally has some stock stroke hemi cranks on the shelf for a reaonable price for new  It's your call
Last edited by Cab_Burge; 07/24/16 03:16 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Balancing a Hemi question.
[Re: dogdays]
#2116530
07/24/16 10:36 AM
07/24/16 10:36 AM
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Joined: Nov 2011
Posts: 290
PA
Harry's Taxi 2
enthusiast
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enthusiast
Joined: Nov 2011
Posts: 290
PA
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The 4340 material in those "cheap" Scat and Eagle cranks is far superior to the OEM material, which is probably either 1053 or 5140. It's exactly the same material that you'd find in Molnar or K1 or for that matter a Source 4340 crank. And those forgings probably all came from the same plant. The finishing differs by company, I believe.
Hemi parts are very heavy and I'd look seriously at taking weight out of the rods and pistons by using more modern designs. It'll make balancing a heck of a lot easier and the engine accelerate noticeably quicker.
You may also want to consider moving up to a US-forged crank with center counterweights.
IMHO, using a reworked 40+ year old crank with millions of stress cycles in a new expensive build is foolish. The fatigue strength of steel is approximately 57% of new strength, and most any used crank has accumulated sufficient cycles to reduce the strength that much. So your used stock crank has two strikes on it before the engine is even fired up.
It's free advice, take it or leave it.
R. What are some names of the US-forged cranks with the center counterweights? Thanks
'86 Maple Grove KOS Mopar low qualifier......true street legal with no power adders.
NOS-used when losing since 1940.
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Re: Balancing a Hemi question.
[Re: fastmark]
#2116857
07/24/16 09:37 PM
07/24/16 09:37 PM
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Joined: Jan 2003
Posts: 75,134
A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,134
A Banana Republic near you.
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Well, I should add that this motor will never see a race track or be run hard at all. It is a street motor just for the cool factor when you open the hood at a car show. He already has one Hemi with a 440 crank that is running for the last 10 years. If you are dead set on using the 440 crank it's either lightweight pistons , or heavy metal , hemi pistons are heavy , the throws on the 440 crank are not going to be heavy enough. Buy the eagle, or scat, HEMI crank if you are going to use the heavy pistons.
running up my post count some more .
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Re: Balancing a Hemi question.
[Re: fastmark]
#2116881
07/24/16 10:35 PM
07/24/16 10:35 PM
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Joined: Jan 2003
Posts: 75,134
A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,134
A Banana Republic near you.
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Thanks, John, someone finally answered the question. It can't be done without heavy metal. That's what I needed to know. I internally balanced a 440 crank that had 6pk pistons and the 6pk rods, we had to add a small amount of metal to the front and rear throws ... luckily the shop I used had lots of small pieces left from propir jobs so it didn't cost me a whole lot. I can't see a 440 crank not getting metal added with a stock type hemi piston.
running up my post count some more .
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