290 vs 343 flywheel??
Printed From: TheAMCForum.com
Category: The Garage
Forum Name: Transmission & Drivetrain
Forum Description: If it's between the engine and wheels, it goes here
URL: https://theamcforum.com/forum/forum_posts.asp?TID=98104
Printed Date: Apr/20/2024 at 5:35am
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Topic: 290 vs 343 flywheel??
Posted By: knightflight
Subject: 290 vs 343 flywheel??
Date Posted: Jan/13/2019 at 12:21am
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I am trying to figure out the difference between a 343 and a 290 flywheel. I don't have the two to compare but I notice they are being sold as one or the other. Since they are the same crankshaft (right??), why a different flywheel? Balancing has to be the same as well as clutch type. They seem interchangeable to me.. What am I overlooking? I ask because I need one for each engine, but it seems to me that I'm needing two of the same thing.. Walt ------------- '68 Rebel SST coupe. (X2) '69 SC/Rambler (#7 on registry) '69 Javelin SST Go-Pak 390-4 speed '70 Rebel Machine 4spd '72 Javelin AMX 360 ram-air |
Replies:
Posted By: 401MATCOUPE
Date Posted: Jan/13/2019 at 5:04am
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the balance is different, remember the balance is done with all rotative components...yes the crank is the same and so are rods/rod bearings.....BUT different pistons, rings and front dampener. The raw casting would be the same, but if you are trying to swap, it needs to come from know engine size. If you are rebuilding and re-balancing anyway......you can use either in the initial balance and it will be adjusted (adding and subtracting weight) ------------- 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 |
Posted By: SC397
Date Posted: Jan/13/2019 at 8:04am
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Upper left is a 290 flywheel. Upper right is a 343 flywheel. The only visual difference is the balancing holes that were drilled in to the 343 flywheel (bottom area of the flywheel) https://flic.kr/p/22idWr2" rel="nofollow">
 https://flic.kr/p/22idWr2" rel="nofollow - 290242390 by https://www.flickr.com/photos/149168736@N07/" rel="nofollow - Rick Jones , on Flickr |
Posted By: pacerman
Date Posted: Jan/13/2019 at 8:41am
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Anecdotal I'm sure: I am finally assembling my 343 factory short block for my AMX. I could not find a 343 flywheel but I did find a NORS Scheiffer 40-pound flywheel with the correct part number for a 343. I had the whole assembly precision balanced as recommended by the Scheiffer literature. The balance shop in Gilroy said it was 52 grams out of balance so I'm glad I did it. Joe ------------- Happiness is making something out of nothing. |
Posted By: knightflight
Date Posted: Jan/13/2019 at 5:20pm
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Hey guys, thanks for the informative input. So, from all that, it looks like I CAN use either one, as long as I am having it balanced with an engine rebuild...correct? Walt ------------- '68 Rebel SST coupe. (X2) '69 SC/Rambler (#7 on registry) '69 Javelin SST Go-Pak 390-4 speed '70 Rebel Machine 4spd '72 Javelin AMX 360 ram-air |
Posted By: purple72Gremlin
Date Posted: Jan/13/2019 at 5:51pm
| make sure the machine shop understands that the AMC v8 is externally balanced. I paid a machine shop to balance my one 360 with a 304 flywheel and balancer....it still vibrated..total waste of my money. |
Posted By: 401MATCOUPE
Date Posted: Jan/13/2019 at 6:44pm
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Walt, you are absolutely correct, I have never had a AMC vib after rebuild/rebalance, I do everyone, same shop...over 100 of them now. ------------- 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 |
Posted By: SC397
Date Posted: Jan/13/2019 at 8:07pm
Same here.
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401MATCOUPE wrote:Posted By: knightflight
Date Posted: Jan/13/2019 at 8:13pm
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SC397... It appears the flywheels you have pictured are all indexed in the same mount position, right? I see the red marks at the 7 o'clock hole on each one. I assume that is why those are there. The pics helps a lot, thank you. Walt ------------- '68 Rebel SST coupe. (X2) '69 SC/Rambler (#7 on registry) '69 Javelin SST Go-Pak 390-4 speed '70 Rebel Machine 4spd '72 Javelin AMX 360 ram-air |
Posted By: SC397
Date Posted: Jan/14/2019 at 7:13am
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Yes, they are all indexed in the same position. Here is a picture of the other side. https://flic.kr/p/FwSVFd" rel="nofollow">  https://flic.kr/p/FwSVFd" rel="nofollow - 867 by https://www.flickr.com/photos/149168736@N07/" rel="nofollow - Rick Jones , on Flickrhttp://rebsamcandjeep.proboards.com/thread/585/amc-290-401-flywheels-flexplates
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Posted By: Steve_P
Date Posted: Jan/17/2019 at 6:54pm
| Ideally, you want to use a 343 flywheel on the 343 or they will have to add weight. It's cheaper to remove weight than add. |