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AMC Harmonic Vibration Damper Listing

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sweatlock View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote sweatlock Quote  Post ReplyReply Direct Link To This Post Posted: Nov/09/2015 at 4:28pm
I contacted Damper Doctors to have my 360 damper rebuilt - no response. I ended up just re-using it since it really wasn't bad, just figured I'd have it re-done while I had it off. Still though, not bothering to answer a potential customer's inquiry..oh well. Hopefully you'll have better luck.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMC Okie Quote  Post ReplyReply Direct Link To This Post Posted: Nov/10/2015 at 10:29am
Is there any way to tell on a 390 c.i. if the engine is a 68-69 or a 70 in case the wrong Harmonic balancer was used?
Also any way to tell if the crank is 68 -69 or 70?
The car is a 69 AMX and it does have a vibration that goes from heavy to light continuously . ....Does that make since? 
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Post Options Post Options   Thanks (1) Thanks(1)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: Nov/10/2015 at 10:31am
look at the casting numbers on the damper....70 damper ends in 6925. The number is cast into the face of the outer ring.
Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar)
68X,GoPac,390,4sp,52A
69X,GoPac,390,4sp,64A
70X,GoPac,390,4sp,87A,8
70X,GoPac,390,4sp,BBO,8
70 Jav SST,390,AT,BSO
74MatX,401,AT,Prototype
74MatX,401,AT
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMC Okie Quote  Post ReplyReply Direct Link To This Post Posted: Nov/10/2015 at 11:51am
Thanks for the info on the balancer.
Do you know how to tell what year the block or crank is?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: Nov/10/2015 at 3:22pm
Block is easy...1/2" head bolts and casting number on back of block....

All 390 cranks are forged, most 70 cranks are re-part numbered 68/9 cranks.....all are flat flanged.  The crank also has a month/date stamped in the wide counter balance throw.  like 11 over 69....they all use the same size bearings (nominal).  The rod is the big difference in 68/9 and 70.  The 68/9 rod ends in 1739 and the 70 rod ends in 7047.  Hope this helps
Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar)
68X,GoPac,390,4sp,52A
69X,GoPac,390,4sp,64A
70X,GoPac,390,4sp,87A,8
70X,GoPac,390,4sp,BBO,8
70 Jav SST,390,AT,BSO
74MatX,401,AT,Prototype
74MatX,401,AT
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMC Okie Quote  Post ReplyReply Direct Link To This Post Posted: Nov/10/2015 at 5:00pm
Yes, all this info is helpful. I worked on alot of amc's in my late teens & early twenties but I've forgot a lot of what I learned, and didn't learn as much as I thought I needed to know about amc's.
I just got off work and looked and it does have a 68/69 balance. I could not find the numbers but it looks like the 68/69 on the first page.
Thanks 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jrpark22000 Quote  Post ReplyReply Direct Link To This Post Posted: Nov/11/2015 at 3:24pm

I've read through this and the countless other damper threads. I haven’t been able to find a definitive answer. 

AMC 360 dampers– did they only come with 180deg weighted, only come with 240deg or a mix depending on the year?

From what I’ve gathered from all the reading I think they were only 240deg weighted.

Why I’m asking;

I ordered a 360 short block from CME and had them order an ATI damper and flywheel so it could be computer balanced. To my surprise when I received the shipment the ATI damper they sent was the 180deg version, part# ATI917942.  I don't have or know what damper came on the motor from AMC.

When I opened the damper box there’s no way they installed it on the crank, there are no marks inside the hub or key way. There’s also new balancing holes drilled into the crank front two counterweights and another in the rear most counterweight. I don’t want to find out the hard way on first startup I’ve the wrong parts.


Thanks Guys. 



Edited by jrpark22000 - Nov/11/2015 at 4:02pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jrpark22000 Quote  Post ReplyReply Direct Link To This Post Posted: Nov/17/2015 at 8:12pm
The answer for anyone following this in the future is 360s were 240 weighted only. 

http://theamcforum.com/forum/topic74921_post677719.html#677719


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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Apr/26/2017 at 9:07am
If you need help internal balancing your AMV8 rotating assembly, PM or or contact me through link below.

443 XRV8 Gremlin YouTube video: https://www.youtube.com/watch?reload=9&v=2DmFOKRuzUc
XRV8 Race Parts website: http://amcramblermarlin.1colony.com/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DHACKING Quote  Post ReplyReply Direct Link To This Post Posted: May/05/2018 at 10:27pm
I HAVE A 1970 AMX THAT WAS AN ORIGINAL 360...NOW HAS 1970 390 IN IT.
THE CASTING # ON THE HARM BALANCER IS '70 390: #3196925.
THE PREV OWNER ALSO PUT IN A 727 TRANS.
SHOULD I BE CONCERNED ABOUT CHANGING THE BALANCER??
THANX...
CONFUSED
RAYMON H
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