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Neutral balancing |
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DaemonForce
AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070 |
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Posted: Jun/25/2017 at 5:53pm |
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Just a quick poll since I want to see what you guys think. Personally I've been looking into ways to extend the life of this old V8 and it seems like neutral balancing the crank in the same fashion as the AMC 6 is the way to go for expanding flexplate/flywheel->transmission options and extending the overall life and purpose of the engine. There's always a good chance I'm wrong about this since these engines are so unusual but I figure any highly desired transmission fitted to a TJ or XJ should be able to make its rounds all the way back to the AMC V8, even if some modification is needed to keep things under control.
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1971 Javelin SST
American 304 2v | FMX | AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI | 1982 NWC T-5M (4.03/.76) | Dana30IFS/35-2.72 |
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amcfool1
AMC Addicted Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1075 |
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hi, if you have the original flexplate, and balancer, you are good to go. Why bother with neutral balancing?
Now you will have to source neutral balancers/flexplates, which do not exist for AMC V8s, (afaik) . If you ever get to the point of having this engine professionally rebuilt, the shop should balance it as a matter of course. It's not rocket science, just AMC specific engine building. good luck, gz
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george z
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tufcj
Supporter of TheAMCForum Supporter of TheAMCForum Joined: Jul/10/2007 Location: Watkins, CO Status: Offline Points: 4085 |
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Why? Factory external balance engines ran 100K. Having a good machine shop balance it the same way is better than factory. My shop balances to 1/4 gram. Factory stuff is usually within 3 to 4 grams.
XJ and TJ were all I-6 engines, the transmissions were only built for that HP/torque, they wouldn't live long behind a healthy V-8. Short Jeep bellhousings will mate up to most Ford trans patterns, and QuickTime has a bellhousing to mate to GM patterns. That gives you a pretty wide selection. I'm currently putting a Legend SS700 in my Rambler. Bob tufcj |
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69 AMX
74 Javelin AMX 67 Rogue If you need a tool and don't buy it... you'll eventually pay for it... and not have it. Henry Ford |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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IIRC the late six flywheel will bolt to the V-8, and is the same diameter, so a neutral flywheel shouldn't be a problem... unless I'm wrong. Still, a good balance job will increase longevity if that's what you're after, doesn't matter if it's internal or external balance.
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Frank Swygert
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5457 |
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What would qualify as a "late" six? |
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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jcisworthy
AMC Addicted Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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Internal balance gets rid of the weight on perimeter the externals, the damper, flexplate, flywheel. Without the weight they will spin true and the counter balance is moved closer to the center of the crank. It is easier on the main bearings and helps to get rid of crank rocking In my opinion it is better for any engine but the cost to balance is typically double or more. Anytime you have weigh on the perimeter of a spinning circle it is not good, surely not as good as it could be without it but it works every day in a lot of applications. |
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Specializing in dyno services, engine building, and cylinder head porting
rbjracing.com Phone Number 518-915-3203 |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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You can internally balance an externally balanced engine,
but I doubt you'll see enough of a longevity benefit to warrant the cost, unless you're at the point where RPM, horsepower or torque are starting to distort the crank or a weak block is starting to move around. There's other reasons to do it, but if the block and crank are good for your power levels, I don't think you'll see an internally balanced engine outlast an externally balanced one just based on that. Edit ^John explains it better above |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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amc67rogue
AMC Addicted Joined: Nov/05/2008 Location: Phx. AZ. Status: Offline Points: 1578 |
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Keith Coggins 67Rogue X code
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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Yep, 72 and later is the "late" six. 72-80 uses a heavier crank and flywheel than 81 and later (including the 4.0L). The actual change for the light weight 1980+ six is January 1980, so early 80 models have the heavy crank, late 80 models the light (entire engine, not just crank... plastic valve cover and aluminum intake also).
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Frank Swygert
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