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360 crank turned down to 340 #1091900 10/10/11 12:31 AM 10/10/11 12:31 AM
Joined: Sep 2009 Posts: 215 mo A ALKYW5DART OP enthusiast
ALKYW5DART OP enthusiast A Joined: Sep 2009 Posts: 215 mo	i am going to bottle my motor next year so my stock 360 block will be retired this winter and i am going to get a 340 resto block. i have a eagle 4340 360 main crank i will need it turned from 2.8 main size to 2.50 340 size, is there plenty of material in the crank to turn it down and still be strong for nitrous

Re: 360 crank turned down to 340 [Re: ALKYW5DART] #1091901 10/10/11 01:10 AM 10/10/11 01:10 AM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	we've done several in house. any reputable shop should be able to do it. if done right it's not a problem. the rear main seal area needs to be cut down to 340 size also. machine shop owner and engine builder

Re: 360 crank turned down to 340 [Re: Performance Only] #1091902 10/10/11 06:24 AM 10/10/11 06:24 AM
Joined: Jul 2009 Posts: 413 Norway (old world) Oyvind Mopar mopar
Oyvind Mopar mopar Joined: Jul 2009 Posts: 413 Norway (old world)	Can this be done safely for an original iron crank if done with generous radii, and say for high perf street use max 7000 rpm, 11:1 CR auto trans?

Re: 360 crank turned down to 340 [Re: Oyvind Mopar] #1091903 10/10/11 12:00 PM 10/10/11 12:00 PM
Joined: Jan 2003 Posts: 9,892 Weddington, N.C. Streetwize master
Streetwize master Joined: Jan 2003 Posts: 9,892 Weddington, N.C.	There seems to still be plenty of the 3.51" to 3.55" MP forged 8 bolt 340 main cranks out there...most of them are very reasonably priced and stronger than you'd ever need. I ran a 3.55" in a little 318 roller block a while back. I know it's done but I'm not a big fan of turning much meat off of a cast crank, at least not when there's a reasonably priced forging available. WIZE World's Quickest Diahatsu Rocky (??) 414" Stroker Small block Mopar Powered. 10.84 @ 123...and gettin' quicker! https://www.youtube.com/watch?v=-mWzLma3YGI In Car: https://www.youtube.com/watch?v=PjXcf95e6v0

Re: 360 crank turned down to 340 [Re: Streetwize] #1091904 10/10/11 08:27 PM 10/10/11 08:27 PM
Joined: Feb 2009 Posts: 1,532 off the grid 340B5 pro stock
340B5 pro stock Joined: Feb 2009 Posts: 1,532 off the grid	Or you could just find someone w/ a factory forged crank laying around. Yeah, it's got a smallblock.

Re: 360 crank turned down to 340 [Re: Streetwize] #1091905 10/10/11 10:25 PM 10/10/11 10:25 PM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	Quote: There seems to still be plenty of the 3.51" to 3.55" MP forged 8 bolt 340 main cranks out there...most of them are very reasonably priced and stronger than you'd ever need. I ran a 3.55" in a little 318 roller block a while back. I know it's done but I'm not a big fan of turning much meat off of a cast crank, at least not when there's a reasonably priced forging available. i agree with you regarding the cast crank. if your going to abuse it with 500HP or nitrous, etc, forget it. for a daily driver or torque combo though they work just fine. on a 4340 crank it's not a problem at all. plenty of meat to remove and retain the strength needed if ground properly. machine shop owner and engine builder

Re: 360 crank turned down to 340 [Re: 340B5] #1091906 10/11/11 02:15 PM 10/11/11 02:15 PM
Joined: Jan 2003 Posts: 16,123 Grand Haven, MI patrick I Live Here
patrick I Live Here Joined: Jan 2003 Posts: 16,123 Grand Haven, MI	Quote: Or you could just find someone w/ a factory forged crank laying around. a stock, OEM factory FORGED 360 crank is more rare than a jackelope...never made 'em 1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod SOLD!* 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)

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