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360 flywheel understanding

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mopar440cu View Drop Down
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    Posted: May/29/2016 at 1:51pm
Good Afternoon gentlemen

I, as you know from my previous posts, are in the process of putting in a 360 in my newly acquired CJ5 and want to clarify some thing up about the flywheel on it. When I picked up my core 360 it had no flywheel on it but, the guy threw one in that he had laying around the shop. He was unsure if it indeed went to that motor. The only number on the flywheel it self is 3212621 and it could go for either 360 or 304, according to some of the readings I found but, I dont understand how? I do understand that I should first check to see if it actually bolts up to the 360 I got but, should I use it if it does bolt up and just have a local machine shop balance it? Or should I just purchase a flywheel from summit or jegs? I am going to order my harmonic balncer from the Balance Dotor and I understand it has got to be balanced also, but some people say both should be balanced together. Is this right or can I order a new balancer from the Doctor and get my a new flywheel from summit/jegs? I am a bit confused? Any advise would be appreciated! I hope i have not lost any of you with my questions if so, I will be more specific.Big smile

Steve
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Post Options Post Options   Thanks (1) Thanks(1)   Quote kenoshakicker Quote  Post ReplyReply Direct Link To This Post Posted: May/29/2016 at 5:18pm
Here is a thread I started that turned into a 360 flywheel discussion.  http://theamcforum.com/forum/topic74336.html  
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Post Options Post Options   Thanks (1) Thanks(1)   Quote rugerfreak916 Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 2:08am
mopar I am also building a 360 for my cj5. I had a flywheel with my motor and ordered my harmonic balancer from summit. 304 and 360 flywheels are different. it should bolt up to the crank but the 304 is internally balanced. look on the motor side of your flywheel. if there is a big block cast in it on the outer edge then it is a 360 if not 304. post a pic. i'm not sure about them having to be balanced together.. i'm guessing in a 5 your not holding it at 6000 for hours so i'd say you would probably be fine. how far are you along are you on the build? i'm shooting to stab mine next weekend.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 7:46am
Do a search. ALL AMC V-8s are EXTERNALLY balanced. Because the 304 pistons are smaller and lighter, the balance is different. The above post is correct, the 360 flywheel will have a block about 1" square cast in near the outer ring, the 304 doesn't.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote mopar440cu Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 8:56am
Originally posted by tufcj tufcj wrote:

Do a search. ALL AMC V-8s are EXTERNALLY balanced. Because the 304 pistons are smaller and lighter, the balance is different. The above post is correct, the 360 flywheel will have a block about 1" square cast in near the outer ring, the 304 doesn't.

Bob
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Bob, I have searched and researched trust me. I understand AMC are externally balanced. I just can not find the exact answers to what I am asking. Thank you for telling me about the block cast in the outer ring I will check for that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mopar440cu Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 9:10am
Originally posted by rugerfreak916 rugerfreak916 wrote:

mopar I am also building a 360 for my cj5. I had a flywheel with my motor and ordered my harmonic balancer from summit. 304 and 360 flywheels are different. it should bolt up to the crank but the 304 is internally balanced. look on the motor side of your flywheel. if there is a big block cast in it on the outer edge then it is a 360 if not 304. post a pic. i'm not sure about them having to be balanced together.. i'm guessing in a 5 your not holding it at 6000 for hours so i'd say you would probably be fine. how far are you along are you on the build? i'm shooting to stab mine next weekend.

My research on the subject to whether or not the flywheel has to be balanced with the harmonic balancer on the crank by the machine shop is still cloudy. On the Jeep blogs some people just bought a new harmonic balancer and new flywheel and bolted them on with no problems. Others are saying have them balanced. I dont know which way to turn?Confused
 

As for my Jeep, I have the frame all painted, the t-18a rebuilt, Dana 20 rebuilt, SOA done and rebuilt axles with 4:56 gears. I am just need of a motor for this one I will try to download a pic for ya. I had a Cj5 with a built Chevy small block stroker, NOS,  turbo 350, SCS t-case, 2 1/2 ton axles with 57 R1 tractor tires but sold it. I got tired of buying racing fuel and other expenses that added up for a weekend. It was easy to drop $500 a weekend and I dont miss it, just the friends that were there. Lol  AMC motors are a whole new beast to me, confusing at times but, its fun learning.WinkSmile
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Post Options Post Options   Thanks (1) Thanks(1)   Quote mstrcrftr Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 9:12am
to answer the question in short,  yes the harmonic, crank, rods and flywheel all need to be balanced together.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mopar440cu Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 9:38am
See if these pics of the flywheel come thru

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 9:41am
Originally posted by mstrcrftr mstrcrftr wrote:

to answer the question in short,  yes the harmonic, crank, rods and flywheel all need to be balanced together.


:iagree:  I hate to state the obvious but it would be difficult to balance an externally balanced engine with the two external balance planes (damper and flywheel) missing.

The only exception would be if the rotating assembly was balanced internally (neutral balance) with heavy metal.  In this case then both the damper and flywheel would have to have neutral balance.  Of course this would not be the stock approach.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mopar440cu Quote  Post ReplyReply Direct Link To This Post Posted: May/30/2016 at 9:44am
Originally posted by rugerfreak916 rugerfreak916 wrote:

mopar I am also building a 360 for my cj5. I had a flywheel with my motor and ordered my harmonic balancer from summit. 304 and 360 flywheels are different. it should bolt up to the crank but the 304 is internally balanced. look on the motor side of your flywheel. if there is a big block cast in it on the outer edge then it is a 360 if not 304. post a pic. i'm not sure about them having to be balanced together.. i'm guessing in a 5 your not holding it at 6000 for hours so i'd say you would probably be fine. how far are you along are you on the build? i'm shooting to stab mine next weekend.

Here is just a pic of the frame and 360 core I have

With no id tag on the valve cover I am guessing the motor is older than a 70 due to the non flat flange on the crank. Maybe 71- up 360. The heads are bridge type and not to sure by the head cast if the 82 on the head means its an 82 or not?

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