Re: Offset grind 3.75 crank limit
[Re: PorkyPig]
#2428313
01/03/18 03:04 PM
01/03/18 03:04 PM
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Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
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I've thrown away enough cracked stock BB Mopar cranks that came out of bracket cars to have reached the point where I now only use them in pretty basic street or street/strip stuff.
No way would I bother having one offset ground for more stroke when I can get a 4340 piece for under $800.
But that's just me.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Offset grind 3.75 crank limit
[Re: PorkyPig]
#2428355
01/03/18 04:07 PM
01/03/18 04:07 PM
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Joined: Mar 2011
Posts: 3,087 Michigan
A727Tflite
master
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master
Joined: Mar 2011
Posts: 3,087
Michigan
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Interesting - you mention big block cranks cracking - how do the Chevy cranks do, do they crack too or not? Ford?
Just you're observation please.
Last edited by Transman; 01/03/18 06:04 PM.
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Re: Offset grind 3.75 crank limit
[Re: PorkyPig]
#2428531
01/03/18 10:18 PM
01/03/18 10:18 PM
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Joined: Jun 2014
Posts: 5,183
Porter67
master
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master
Joined: Jun 2014
Posts: 5,183
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Re: Offset grind 3.75 crank limit
[Re: PorkyPig]
#2428836
01/04/18 01:00 PM
01/04/18 01:00 PM
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Joined: Oct 2007
Posts: 4,209 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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Can't follow the text, they refer to "adding 1/2" to the stroke", using the stock rods (no offset), and 505" with 4.00" is just under 4.500" bore - not something you would do.
Boffin Emeritus
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Re: Offset grind 3.75 crank limit
[Re: polyspheric]
#2428854
01/04/18 01:20 PM
01/04/18 01:20 PM
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Joined: Dec 2013
Posts: 403 Romulus, MI
GTS340
mopar
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mopar
Joined: Dec 2013
Posts: 403
Romulus, MI
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Can't follow the text, they refer to "adding 1/2" to the stroke", using the stock rods (no offset), and 505" with 4.00" is just under 4.500" bore - not something you would do. They welded the journals to get to 4.250 stroke with the stock rods
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Re: Offset grind 3.75 crank limit
[Re: PorkyPig]
#2430364
01/07/18 03:48 AM
01/07/18 03:48 AM
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Joined: Aug 2003
Posts: 43,228 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,228
Bend,OR USA
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If your motor makes 1.2 HP per C.I. how much HP does it gain 451x1.2=541.2 HP compared to 1.2x470=564HP. Of course if it makes more or less HP per C.I. the results will vary accordingly I'm not sure about how much the torque gain and PEAK RPM for both torque and RPM are affected by stroke changes I do know that on my last pump gas street and strip car increasing the stroke .050 (went from 4.25 to 4.300)helped it by .2 ET and 2.5 MPH
Last edited by Cab_Burge; 01/07/18 04:10 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Offset grind 3.75 crank limit
[Re: PorkyPig]
#2430377
01/07/18 04:25 AM
01/07/18 04:25 AM
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Joined: Jan 2003
Posts: 6,591 Canton, Ohio
Sport440
master
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master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
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How much difference would 19 cubic inches really make going from 451 to 470? My 3.75 crank is a new offshore 4340 that measures OK. But if I only go to 3.91 I don't know that it would be worth the money for new rods and pistons with only that much offset grind. If you have all the parts for the 451, rods pistons, etc stay with that. The 451 is a great motor combo.
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