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big G puller Guest
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Posted: Tue Jan 29, 2013 8:41 am Post subject: 3 in journel on a stroker crank hold togeather |
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will a 3 journel on a 9.5 stroker crank with a 7 3/4 bore hold togeather or break? |
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Lynerd Regular
Joined: 10 Jan 2010 Posts: 20
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Posted: Tue Jan 29, 2013 9:20 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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Yes Lynn |
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Josh Blackburn Regular
Joined: 28 Dec 2009 Posts: 406
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Posted: Tue Jan 29, 2013 9:28 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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Why risk it. 5020 3.5 journal. You can still fit 9.5 in easy. |
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Mike N Mo Long Time User
Joined: 20 Aug 2004 Posts: 1144
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Posted: Tue Jan 29, 2013 9:34 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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You'll be better off with a 3.375-3.5" journal size. The 3" will hold for a while, but the bigger ones will last a lot longer. |
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big G puller Guest
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Posted: Tue Jan 29, 2013 9:34 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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josh how much to do a 9.5 or 9.75 with 3.5 journels |
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Brent50G Regular
Joined: 20 Jun 2008 Posts: 41
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Posted: Tue Jan 29, 2013 1:45 pm Post subject: Re: 3 in journel on a stroker crank hold togeather |
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Yes for a couple years as long as u keep it from detonating |
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blackangus Regular
Joined: 27 Oct 2010 Posts: 20
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Posted: Tue Jan 29, 2013 7:58 pm Post subject: Re: 3 in journel on a stroker crank hold togeather |
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Ive got a3.5/8 with 3.5 journal in my 70 very tight |
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Josh Blackburn Regular
Joined: 28 Dec 2009 Posts: 406
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Posted: Wed Jan 30, 2013 4:25 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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1500 includes flywheel-crank-driver assembly balanced as one unit. |
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Tree Topper Guest
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Posted: Wed Jan 30, 2013 11:10 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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I have a 9.75 stroke, 6.375 bore, about 9 to 1 compression. Been running since 2004 with no problems yet. Has been pulled pretty hard in 10,200 lb. class many times. Works real well.
Oh yes it has a 3 inch journal! |
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buickanddeere Tractor Guru
Joined: 31 May 2003 Posts: 23622 Location: in front of computer
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Posted: Wed Jan 30, 2013 12:20 pm Post subject: Re: 3 in journel on a stroker crank hold togeather |
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She has to last in order to place first |
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Mike N Mo Long Time User
Joined: 20 Aug 2004 Posts: 1144
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Posted: Wed Jan 30, 2013 1:27 pm Post subject: Re: 3 in journel on a stroker crank hold togeather |
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Tree Topper, Your 3" journal should be very reliable at 622 cu in. We're running 3" journals on A's with more cubes than that, and just replaced a crank after 6 years (before it broke). The engine in question will have 896 cubes, almost half again more than yours, and needs the bigger journal to have decent reliability. Mike |
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Big G puller Guest
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Posted: Wed Jan 30, 2013 3:41 pm Post subject: Re: 3 in journel on a stroker crank hold togeather |
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well iv been running this crank for 7 yrs with 3 in journels 7.5 block thats 832 cubes block went bad so if im gonna replace block to 7 3/4 im going with a new crank shaft befor it breaks |
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buickanddeere Tractor Guru
Joined: 31 May 2003 Posts: 23622 Location: in front of computer
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Posted: Thu Jan 31, 2013 5:17 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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A 3.5" journal has 1.361 times more material than a 3.0" journal. |
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Tree Topper Guest
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Posted: Thu Jan 31, 2013 9:54 am Post subject: Re: 3 in journel on a stroker crank hold togeather |
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Yes I know this is not a very big G as compared
to what is being built these days, but this set up has worked very well for me. Been very reliable. Don't use the engine up very often even in heavy classes. Lots of fun. |
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Indiana Ken Regular
Joined: 10 May 2011 Posts: 397 Location: Northern Indiana
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Posted: Thu Jan 31, 2013 7:12 pm Post subject: Re: 3 in journel on a stroker crank hold togeather |
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| buickanddeere wrote: | | (quoted from post at 06:17:31 01/31/13) A 3.5" journal has 1.361 times more material than a 3.0" journal. |
Yes, this would be correct for cross sectional area. The strength of the journal in tension is proportional to the cross sectional area. However, for a crankshaft, strength in torsion and strength in bending are more important than strength in tension.
If I could repeat your calculations for clarity: The cross sectional area is proportional to the diameter raised to the second power (diameter squared). For a 3" journal we have 3^2 = 9 and for a 3.5" journal we have 3.5^2 = 12.25. 12.25 divided by 9 = 1.361; increase in strength in tension.
The strength of the journal in torsion and in bending is proportional to the journal diameter raised to the fourth power. For a 3" journal we have 3^4 = 81 and for a 3.5" journal we have 3.5^4 = 150.06. 150.06 divided by 81 = 1.85; increase in strength in torsion and bending.
In conclusion the 3.5" journal is nearly double in stength for the more important torsion and bending modes.
With all respect - hopefully this adds to your post. Ken |
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