TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC V8 Engine Repair and Modifications
  New Posts New Posts RSS Feed - Auto Tran to Man swap violent shake
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

Auto Tran to Man swap violent shake

 Post Reply Post Reply Page  123 4>
Author
Message
chrizti4 View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Jul/01/2019
Location: Wentzville, MO.
Status: Offline
Points: 14
Post Options Post Options   Thanks (0) Thanks(0)   Quote chrizti4 Quote  Post ReplyReply Direct Link To This Post Topic: Auto Tran to Man swap violent shake
    Posted: Jul/02/2019 at 9:14am
AMC Friends, I'm stumped! 1978 CJ7, removed 304 3spd swapped in running (78?) 360 out of a J10 auto. Ordered flywheel and input shaft bushing and installed working 5spd. Engine starts fine, no odd sounds from starter or anything. At 800 rpm shakes violently till around 3k (didn't go higher than that). Engine responds like its new, no blow by, no burning oil on accel or de-accel. Vac gauge at a solid stable 16lbs needle has no waiver or shake, timing and firing order checked four times, 5degBTDC with ported line attached. Changed plugs, wires, dist cap. Header temp only varies <50deg between pipes. Don't want to (shouldn't) drive it with SHAKING the whole jeep. Doesn't overheat, stays a good 165. Carb flow checked, and everything within standards. After warmed up did rev it a bit, sounds fantastic with both open headers and with mufflers installed, shaking doesn't change. But at idle smooth as a kitten and when hitting accelerator smooth as a tiger. Have built a lot of vehicles, this is second AMC build. I AM STUMPED! I know some say the 401 has a different flywheel, but I ordered one for a 360. Next step is dropping drive-train, installing the old flex-plate, building a temp rear block mount and starting the engine again. Is there anyway to tell if the flywheel is the wrong one? Thank you sir!
Respectfully submitted,
Christopher Wuertz
Back to Top
ramblinrev View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: Dec/28/2008
Location: Wisconsin
Status: Offline
Points: 11469
Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 9:46am
Yes, sounds like you have an engine balance issue.
The manual flywheel (correct or not) is not going to have the same balance as an automatic flexplate.
74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384
70 AMX 360 4-speed (since 1981)
Back to Top
chrizti4 View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Jul/01/2019
Location: Wentzville, MO.
Status: Offline
Points: 14
Post Options Post Options   Thanks (0) Thanks(0)   Quote chrizti4 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 9:47am
Thank you sir for the response, how do I fix this?
Back to Top
tufcj View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Supporter of TheAMCForum

Joined: Jul/10/2007
Location: Watkins, CO
Status: Offline
Points: 4065
Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 9:54am
Did you use the 304 flywheel or order one for a 360?  AMC V-8s are externally balanced.  The flywheel (and harmonic balancer) have to be for your specific displacement.

If you still have the automatic flexplate that came off the 360, you can take that and the flywheel to an automotive machine shop and have them "match balanced".

Bob
tufcj
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
Back to Top
BrotherBamc View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jan/22/2009
Location: Lewiston
Status: Offline
Points: 2248
Post Options Post Options   Thanks (0) Thanks(0)   Quote BrotherBamc Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 10:01am
Have your flywheel neutral balanced... 
A reputable machine shop that does balancing will be able to help you out with that. 

77 CJ5 360
73 Gremlin 401 4 speed
2006 Dodge Magnum R/T AWD
My Garage
Back to Top
SC397 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Apr/30/2009
Location: Michigan
Status: Offline
Points: 5428
Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 10:16am
A pleasure to meet you Mr. Stumped,
If you have the original flex plate from the 360 you could have a machine shop match-balance the new flywheel to the old flex plate.  Or, disassemble the engine and have a machine shop externally balance the rotating assembly.
Back to Top
mark09 View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Dec/14/2012
Location: indiana
Status: Offline
Points: 279
Post Options Post Options   Thanks (0) Thanks(0)   Quote mark09 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 11:44am
Brotherbamc there's a big difference between neutral and match balance.
V-8 's not  neutral ballance unless specifically done at a rebuild .
Back to Top
Greyhounds_AMX View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Nov/14/2009
Location: Kansas City
Status: Offline
Points: 1268
Post Options Post Options   Thanks (1) Thanks(1)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 12:13pm
Originally posted by ramblinrev ramblinrev wrote:

Yes, sounds like you have an engine balance issue.
The manual flywheel (correct or not) is not going to have the same balance as an automatic flexplate.

They actually would have the same balance. When I converted from auto to stick, I had my new flywheel match balanced to the old flexplate. My engine had previously been rebuilt and rebalanced, so stock balance weighting didn't apply anymore.

I recently had a friend with a similar problem and it turned out to be the clutch/pressure plate that was the culprit. You might try it with the clutch and pressure plate removed but keep the current flywheel and see what happens.
1968 AMX 390 w/T5
Back to Top
BrotherBamc View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jan/22/2009
Location: Lewiston
Status: Offline
Points: 2248
Post Options Post Options   Thanks (0) Thanks(0)   Quote BrotherBamc Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 12:59pm
Originally posted by mark09 mark09 wrote:

Brotherbamc there's a big difference between neutral and match balance.
V-8 's not  neutral ballance unless specifically done at a rebuild .


I stand corrected then...
I had a 360 flywheel "neutral balanced" when I put a T-10 behind my 258.
I believe that the 258's are externally balanced then..??
77 CJ5 360
73 Gremlin 401 4 speed
2006 Dodge Magnum R/T AWD
My Garage
Back to Top
tufcj View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Supporter of TheAMCForum

Joined: Jul/10/2007
Location: Watkins, CO
Status: Offline
Points: 4065
Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 1:19pm
Originally posted by BrotherBamc BrotherBamc wrote:


I stand corrected then...
I had a 360 flywheel "neutral balanced" when I put a T-10 behind my 258.
I believe that the 258's are externally balanced then..??


Neutral balance is correct on an I-6.  Those are INTERNALLY balanced. 

V-8s are EXTERNALLY balanced and rely on the harmonic balancer and flywheel/flexplate for balancing.

Bob
tufcj
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
Back to Top
 Post Reply Post Reply Page  123 4>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.125 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or