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318 crank in a 340???? #154826 11/22/08 09:59 AM 11/22/08 09:59 AM
Joined: Mar 2003 Posts: 1,728 ST clair shores MI M moretoys OP top fuel
moretoys OP top fuel M Joined: Mar 2003 Posts: 1,728 ST clair shores MI	Any real drawbacks besides a 340 crank being stronger.any other issues???same stroke, same beaing sizes,still steel crank.Is strength the only plus with a 340 crank??

Re: 318 crank in a 340???? [Re: moretoys] #154827 11/22/08 10:42 AM 11/22/08 10:42 AM
Joined: Jan 2007 Posts: 7,664 IN A ahy master
ahy master A Joined: Jan 2007 Posts: 7,664 IN	I believe 318 transitioned to a cast crank in the 60's. The 340 transitioned to cast around 73/74. I'm sure somebody will provide exact dates and maybe some pics to help tell the difference. That being said, a well preppped cast crank should be good for 350 - 400 HP so it depends on your build.

Re: 318 crank in a 340???? [Re: ahy] #154828 11/22/08 11:02 AM 11/22/08 11:02 AM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	balance will be different too. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: 318 crank in a 340???? [Re: Supercuda] #154829 11/22/08 11:05 AM 11/22/08 11:05 AM
Joined: Jan 2003 Posts: 10,968 Hampton, Ga. 7 70dart360 Green Meister
70dart360 Green Meister 7 Joined: Jan 2003 Posts: 10,968 Hampton, Ga.	Quote: balance will be different too. I thought they were both neutral balanced 70 Dart Swinger 72 D-100 440 shortbed 76 Pinto, 68k 21mpg!

Re: 318 crank in a 340???? [Re: 70dart360] #154830 11/22/08 11:14 AM 11/22/08 11:14 AM
Joined: Aug 2005 Posts: 11,543 chicagoland,usa B buildanother I Live Here
buildanother I Live Here B Joined: Aug 2005 Posts: 11,543 chicagoland,usa	Nuetral balanced means the rotating assembly needs no external balancing. Balance is slightly different (318 to 340) due to heavier pistons, etc. Same holds true for 305 to 350 chev. The difference is not great but should be rebalanced for different displacement.

Re: 318 crank in a 340???? [Re: buildanother] #154831 11/22/08 11:45 AM 11/22/08 11:45 AM
Joined: Apr 2007 Posts: 2,327 Glendale, AZ 6 69L78Nova Banned. Forever.
69L78Nova Banned. Forever. 6 Joined: Apr 2007 Posts: 2,327 Glendale, AZ	The 318 crank went cast in 1973. Forged just like the 340 until then 1969 Nova 454/M21/3.31 Mild mid-11 second weekend cruiser 1994 F150 XLT Super Cab 2WD 5.0/4R70W/3.55 (Daily driver)

Re: 318 crank in a 340???? [Re: 69L78Nova] #154832 11/22/08 12:45 PM 11/22/08 12:45 PM
Joined: Dec 2003 Posts: 5,314 Carstairs, Alberta, Canada dave571 master
dave571 master Joined: Dec 2003 Posts: 5,314 Carstairs, Alberta, Canada	There are actually part numbers for cast cranks in 318's starting in 67 IIRC. It's a common myth that 318's were steel cranks. I've never torn down a LA family 318 that wasn't cast

Re: 318 crank in a 340???? [Re: buildanother] #154833 11/22/08 02:42 PM 11/22/08 02:42 PM
Joined: Jan 2003 Posts: 9,826 las vegas 70AARcuda master
70AARcuda master Joined: Jan 2003 Posts: 9,826 las vegas	Quote: Nuetral balanced means the rotating assembly needs no external balancing. Balance is slightly different (318 to 340) due to heavier pistons, etc. Same holds true for 305 to 350 chev. The difference is not great but should be rebalanced for different displacement. mallory metal will have to be added to the crank to allow for the heavier 340 pistons... finding lighter 340 pistons will help.....so will lighter rods... Tony 70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)

Re: 318 crank in a 340???? [Re: 69L78Nova] #154834 11/22/08 02:57 PM 11/22/08 02:57 PM
Joined: Jan 2003 Posts: 4,150 lewiston, ID C cornucopia
cornucopia C Joined: Jan 2003 Posts: 4,150 lewiston, ID	Quote: The 318 crank went cast in 1973. Forged just like the 340 until then untrue...I have pulled apart MANY 68-72 vintage 318s and they all had cast cranks...

Re: 318 crank in a 340???? [Re: moretoys] #154835 11/22/08 03:02 PM 11/22/08 03:02 PM
Joined: Jan 2003 Posts: 6,816 Alton, IL D Dakota_Don master
Dakota_Don master D Joined: Jan 2003 Posts: 6,816 Alton, IL	my 68 has a steel crank..i have the casting numbers somewhere, it even looks different..kinda rough in some places..

Re: 318 crank in a 340???? [Re: dave571] #154836 11/22/08 03:13 PM 11/22/08 03:13 PM
Joined: Mar 2003 Posts: 1,728 ST clair shores MI M moretoys OP top fuel
moretoys OP top fuel M Joined: Mar 2003 Posts: 1,728 ST clair shores MI	Is the general rule of thumb about cast crank having the thicker balancer gone??

Re: 318 crank in a 340???? [Re: moretoys] #154837 11/22/08 03:21 PM 11/22/08 03:21 PM
Joined: Jan 2003 Posts: 25,200 Upper Midwest M MoparforLife Too Many Posts
MoparforLife Too Many Posts M Joined: Jan 2003 Posts: 25,200 Upper Midwest	All 318's were neutral balanced whether cast or forged shafts. As was the 273.

Re: 318 crank in a 340???? [Re: moretoys] #154838 11/22/08 04:09 PM 11/22/08 04:09 PM
Joined: Dec 2003 Posts: 5,314 Carstairs, Alberta, Canada dave571 master
dave571 master Joined: Dec 2003 Posts: 5,314 Carstairs, Alberta, Canada	Quote: Is the general rule of thumb about cast crank having the thicker balancer gone?? It's a general rule that never applied to 318's or 273's. As mentioned, 318s are neutral ballanced with either cast or forged crank. Here are some part numbers year cid material cast#/forge# 64-67 273 forged 2128278, 2128869, 2205700 68-69 273 cast 2658268, 2658393 67-73 318 cast 2658278, 2658393 74-86 318 cast 2658278, 2658393, 3462387 2658391 68-72 340 forged 2532457, 2843868 73 340 cast 3462387 71-86 360 cast 3418640, 3418641, 3418642

Re: 318 crank in a 340???? [Re: dave571] #154839 11/22/08 06:14 PM 11/22/08 06:14 PM
Joined: Jan 2003 Posts: 3,943 Melbourne.....Oz-land Moparmal master
Moparmal master Joined: Jan 2003 Posts: 3,943 Melbourne.....Oz-land	If you can find a 318-3 truck block, that'll have a forged crank. Not so sure the "limit" on a cast crank is only 400 FWHP either...... ...but I cant say for certain as Ive never torn a 500HP LA down to check...

Re: 318 crank in a 340???? [Re: Moparmal] #154840 11/23/08 01:46 AM 11/23/08 01:46 AM
Joined: Jan 2003 Posts: 6,391 Abilene, Texas F fastmark master
fastmark master F Joined: Jan 2003 Posts: 6,391 Abilene, Texas	I have had a couple of 318 cranks from trucks that were forged steel. Look for the end throws of the rod journals. A steel 318 will not have the 1" hole drilled through the journal and a 340 steel shaft will. They can be balanced to fit in a 340 and work just fine. They are all internally balanced with no counter weight on the balancer or converter.

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