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Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428310
01/03/18 02:55 PM
01/03/18 02:55 PM
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Las Vegas
Al_Alguire Offline
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Lord knows I hate rpm smile


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
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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So. Burlington, Vt.
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fast68plymouth Offline
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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
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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Michigan
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A727Tflite Offline
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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.
Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428384
01/03/18 05:36 PM
01/03/18 05:36 PM
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Porter67 Offline
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May 1980 Hot Rod Mag Al K built a 9:1 505 bracket motor offset a 440 crank to 4.00, six pack rods, iron heads, 332 DC mushroom cam. Mid 10-s in a cuda. Crank work was $300 then.


I can scan it if anyone wants to read it/pics ect.

Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428401
01/03/18 06:05 PM
01/03/18 06:05 PM
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Yes - scan and post please.

Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428530
01/03/18 10:17 PM
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If you save them you can zoom them a bit and read them.

1.JPG2.JPG3.JPG4.JPG
Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428531
01/03/18 10:18 PM
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The Rest

5.JPG6.JPG7.JPG8.JPG
Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428635
01/04/18 12:49 AM
01/04/18 12:49 AM
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Thanks- I remember the article now that I see it. Corky was one of the premier porters back in the 70's and early 80's, Elkins at Diamond was at the top of the heap.

Note the 1.81" exhaust valve, we used those back in the mid 70's - cutting the maxwedge 1.88" down. I sold of bunch of those Stage IV heads back in the day that Corky did for me. Wish I had saved a few sets.

Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428725
01/04/18 04:10 AM
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Its probably been 15 years since I looked at that mag but even then decent mopar builds were not super common then and ive welded and cut alot of cranks over the years for myself, there ugly when balanced but so is my sister and she had two kids. So...

Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428766
01/04/18 10:31 AM
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I wonder how many guys put their favorite racing jacket on when they torque their bolts ?

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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polyspheric Offline
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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.


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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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Romulus, MI
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Originally Posted By polyspheric
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

Re: Offset grind 3.75 crank limit [Re: PorkyPig] #2428975
01/04/18 05:10 PM
01/04/18 05:10 PM
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Las Vegas
Al_Alguire Offline
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My first stroker BB used a welded crank and a Ford piston...Had to get creative in the dark ages smile


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: Offset grind 3.75 crank limit [Re: Al_Alguire] #2430211
01/06/18 10:24 PM
01/06/18 10:24 PM
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PorkyPig Offline OP
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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. As a 451 440 block it can run in the high 10s.

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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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 shruggy
I'm not sure about how much the torque gain and PEAK RPM for both torque and RPM are affected by stroke changes confused work
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 shruggy

Last edited by Cab_Burge; 01/07/18 04:10 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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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Canton, Ohio
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Originally Posted By PorkyPig
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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