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Quick stupid question 74 401 to m12 |
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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Posted: Jul/20/2007 at 6:46am |
I have laying in front of me a 727 flexplate and a m12 flexplate from a 1969 V8. I also have the torque converters. We are installing a 1974 401 in a 500 special (AMX) this evening and I am wondering if the 727 flexplate will work for this. The bolt pattern looks close but I personally havent done this swap. I believe I will need to make a adaptor for the converter spud. Anyone done this swap that can shed a little more light on this?
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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It looks like I just need to open up the mounting holes for the larger bolts on the M12 torque converter.
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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Ok so we have to bore out the center hole in the flexplate, leave a nice radius to allow it to fit on the edge of the end of the later crank. Make a bronze spud to allow the M12 torque converter to join with the later crank.
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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FuzzFace2
AMC Addicted Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10343 |
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Some one does make an adaptor for this, One is a bolt in the other needs machine work-read crank has to be out. Think it might be the people in FL? Dave ---- |
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XJ-001
Supporter of TheAMCForum Joined: Jul/03/2007 Location: Minnesota Status: Offline Points: 193 |
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FF2 - You're thinking of the adapter for the early engine/crank in front of a TH400/727. MC and the car owner are trying to install a later (72-up) 401 in front of a M-12. The 71 401 flexplate has a very small center hole and the crank has the large diameter flange for the 400/727 stlye plate. They need to machine the 401/M-12 flexplate center hole out to the diameter of the late crank flange. The bolt pattern is the same on both cranks, so that won't be an issue. It appears from my discussion with the owner that the M-12 torque converter has enough of a recess to clear the crank flange without binding, but they need to make a special pilot bushing to adapt the M-12 pilot stub to the crank. IIRC, the pilot bushing on the later cranks sits deeper in the flange than on the older cranks, so they'll need to calculate the height difference and make the new bushing that much longer. Or they could take a grinder and grind the flange off the crank!
MC - You'd need to determine if the mounting areas on the 727 flexplate are the same height as the M-12 plate. I don't think they are. It might set the converter too deep into the pump. Edited by XJ-001 - Jul/20/2007 at 5:01pm |
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1970 AMX 390 4spd
1970 Javelin 390 Auto (Project) 2002 Grand Cherokee Overland Edition 2002 Olds Intrigue (The Other Orphan) Bloomington, MN |
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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Here is what I did. I made a steel insert for the back of the crank( slight press fit). I made a .753" hole in the insert for the M12 torque converter spud. I then took the original 1971 401 flexplate and machined out the center to match the later model crank. It went together beautifully! I have pics and will post them later!
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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348AMX
AMC Addicted Joined: Jul/03/2007 Location: Massachusetts Status: Offline Points: 4165 |
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While your in there you might consider upgrading the torque converter. The stock M12 depending on your engine combo gears and weight in most stock AMC cars anyway had a really low stall, like 1300 RPM, Continental converters has been making high stall AMC Borg warner Automatic converters for years. www.ctconverters.com.
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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:) Nice!....7 hours too late but nice!
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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