Shakes really bad at idle
Thread Starter
Racer
Joined: Jun 2015
Posts: 315
Likes: 20
From: Vasteras, Sweden
Shakes really bad at idle
Runs well when it is Cold, starts to shake when it is hot...
New plugs, checked plugwires, HEI distributor with new coil and MSD unit.
Can`t figure it out...maybe bad compression or valve lash issues???
No oil consumption..that should rule out bad compression.
454 Engine with edelbrock 2162 cam. Rebuilt Quadrajet
Suggestions...
New plugs, checked plugwires, HEI distributor with new coil and MSD unit.
Can`t figure it out...maybe bad compression or valve lash issues???
No oil consumption..that should rule out bad compression.
454 Engine with edelbrock 2162 cam. Rebuilt Quadrajet
Suggestions...
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Runs well when it is Cold, starts to shake when it is hot...
New plugs, checked plugwires, HEI distributor with new coil and MSD unit.
Can`t figure it out...maybe bad compression or valve lash issues???
No oil consumption..that should rule out bad compression.
454 Engine with edelbrock 2162 cam. Rebuilt Quadrajet
Suggestions...
New plugs, checked plugwires, HEI distributor with new coil and MSD unit.
Can`t figure it out...maybe bad compression or valve lash issues???
No oil consumption..that should rule out bad compression.
454 Engine with edelbrock 2162 cam. Rebuilt Quadrajet
Suggestions...
Your problem is impossible to diagnose without more information like initial advance and full advance and whether the vacuum advance is working and the choke is fully opening and such. For us to help you we need you to help us.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
You could have a vacuum leak on the other side of a TVS switch, or your choke is making the thing run rich enough to be smooth cold and your actual curb idle warm is just too lean.
Have you checked your idle mixture?
Have you checked your idle mixture?
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
Could be fuel related if when warm. Long shot, but check the harmonic dampener. Had a friend who had a vibration issue and he never noticed his outer ring was about to come off.
manual trans? Like said more details!
manual trans? Like said more details!
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
I recommend replacing the harmonic damper with a modern damper because yours will slip if it hasn't already. The dampers of years ago were 3-piece; an iron hub with an iron outer ring with natural rubber sandwiched in between. After many years of use the rubber hardens and shrinks and the outer ring will slip. The new dampers appear to have an injection-filled RTV type of rubber that will last virtually forever and they're very inexpensive.
Thread Starter
Racer
Joined: Jun 2015
Posts: 315
Likes: 20
From: Vasteras, Sweden
It`s Auto trans, if it`s the balancer why does it not shake when cold?
If i rev it over 1000rpm the shake goes away..
It`s the heat thing i don`t understand, the hotter it gets the more it shakes
If i rev it over 1000rpm the shake goes away..
It`s the heat thing i don`t understand, the hotter it gets the more it shakes
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Race Director
Joined: Jul 2004
Posts: 12,706
Likes: 329
From: Scottsdale Arizona
Assuming that your choke is working properly (including increasing the idle) and there are no misfires at higher RPMs, I would bet on a vacuum leak somewhere. Look for port plugs on the carb that have broken or fallen off. Otherwise, check the carb gasket and intake with carb cleaner ( have a fire extinguisher handy) then start unplugging hoses until the problem goes away. Don't forget to plug the port when you unplug the vacuum hose.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Before doing anything else pull all of the spark plugs out and see if any are soot black. If so they aren't firing and they are likely the cause of your engine shaking so bad at idle.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Had an engine like that once and could never figure it out
Thought it may be lean, vac leak etc. Balancer will make it vibrate no matter what fwiw
Do you know anyone with a smoke machine, they will find a vacuum leak pronto
Thought it may be lean, vac leak etc. Balancer will make it vibrate no matter what fwiw
Do you know anyone with a smoke machine, they will find a vacuum leak pronto
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
My buddies damper would only cause shake at certain rpms. Could be tons of stuff other than tune, like maybe an engine mount. Maybe even a bad ground.
edit: could be the water pump or alt bearing seizing up but when warm they are fine, GL post when you figure it out.
edit: could be the water pump or alt bearing seizing up but when warm they are fine, GL post when you figure it out.
Instructor
Joined: Feb 2014
Posts: 149
Likes: 1
Runs well when it is Cold, starts to shake when it is hot...
New plugs, checked plugwires, HEI distributor with new coil and MSD unit.
Can`t figure it out...maybe bad compression or valve lash issues???
No oil consumption..that should rule out bad compression.
454 Engine with edelbrock 2162 cam. Rebuilt Quadrajet
Suggestions...
New plugs, checked plugwires, HEI distributor with new coil and MSD unit.
Can`t figure it out...maybe bad compression or valve lash issues???
No oil consumption..that should rule out bad compression.
454 Engine with edelbrock 2162 cam. Rebuilt Quadrajet
Suggestions...
Racer
Joined: May 2013
Posts: 421
Likes: 6
From: Chicago IL
I agree with the vacuum leak - had the same thing happen to me. Put your hand over the carb when it is warmed up. If the idle goes up and smooths out, you verified a leak. They can be a pain to search and find them! 