Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 20 of 20 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Hey Y’all, I have a 1965 mustang gt clone I just bought recently. It has a terrible vibration. If the car is parked, in drive, neutral. You can’t feel the vibration with it just idling but as soon as you hit the accelerator the whole car starts to shake. It shakes the whole car and as you eccelerate more it seems to vibrate faster.. I’ve just changed the plugs, no vacuum leaks, as well as the harmonic balancer I just swapped out for a new one. Car was restored 10 years ago she’s a beauty. But not road worthy with this vibration. She’s got a 289, automatic c4. Car is very much bone stock. Thanks so much!!!
 

·
Registered
Joined
·
401 Posts
Hey Y’all, I have a 1965 mustang gt clone I just bought recently. It has a terrible vibration. If the car is parked, in drive, neutral. You can’t feel the vibration with it just idling but as soon as you hit the accelerator the whole car starts to shake. It shakes the whole car and as you eccelerate more it seems to vibrate faster.. I’ve just changed the plugs, no vacuum leaks, as well as the harmonic balancer I just swapped out for a new one. Car was restored 10 years ago she’s a beauty. But not road worthy with this vibration. She’s got a 289, automatic c4. Car is very much bone stock. Thanks so much!!!
First thing I would check is the firing order. 1 5 6 2 4 3 7 8 Amusing it is a 289

yarb
748436
1585443089858.png
 
  • Like
Reactions: myfirstcar66

·
Registered
Joined
·
37,687 Posts
Did it ever run smoothly? If so, did it start to run poorly after doing some work on it or just out of the blue? Have you put a vacuum gauge on it and noted the action and reading of the needle?
 

·
Registered
Joined
·
21,332 Posts
My initial thought is that you have a 5.0 motor. You say you just bought the car and it has a 289. Here's the thing. It's a 50+ year old car. Chances are the typical vintage Mustang is not going to have the original motor. It may look like a 289 but so does my 97 Explorer GT40P in my 66. You very well could have a 5.0 motor dressed to look like a 289 with the wrong harmonic balancer or flywheel.
 

·
Registered
Joined
·
330 Posts
I would be checking to make sure the flexplate and dampener are both 28 oz matching.
 

·
Premium Member
Joined
·
13,214 Posts
Has anybody ever experimented with a 50 oz balancer and flywheel on a 289 just to see how bad the vibration is? Or a 28 oz balancer and flywheel on a 5.0?
Would the vibration be as bad as the OP describes his vibration?
 

·
Registered
Joined
·
8 Posts
Discussion Starter #8
Did it ever run smoothly? If so, did it start to run poorly after doing some work on it or just out of the blue? Have you put a vacuum gauge on it and noted the action and reading of the needle?
I bought the car with the vibration issue.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #10
My initial thought is that you have a 5.0 motor. You say you just bought the car and it has a 289. Here's the thing. It's a 50+ year old car. Chances are the typical vintage Mustang is not going to have the original motor. It may look like a 289 but so does my 97 Explorer GT40P in my 66. You very well could have a 5.0 motor dressed to look like a 289 with the wrong harmonic balancer or flywheel.
Never even thought of that... would they look very similar?
 

·
Premium Member
Joined
·
6,084 Posts
Also if someone installed a 351 / late 302 but are using the 289 / early 302 firing order, it might run with enough advance but I bet it would be like having square wheels on a wagon !
 

·
Registered
Joined
·
8 Posts
Discussion Starter #14
Also if someone installed a 351 / late 302 but are using the 289 / early 302 firing order, it might run with enough advance but I bet it would be like having square wheels on a wagon !
here’s the thing. It runs fine, fires right up. And accelerates how it needs to. Just vibrates like hell....
 

·
Registered
Joined
·
8 Posts
Discussion Starter #15
Never even thought of that... would they look very similar?
here’s my thought... if it was a 302 but they said it’s a 289, the firing order is of a 289. If the firing order is of a 289 but it had a 302 in it it probably wouldn’t even fire up right?
 

·
Registered
Joined
·
11,142 Posts
I was gonna go with the Harmonic ,but you said you changed it. Is it any better worse or different ?
Maybe the bumpstick has a worn lobe or 2 causing a power balance issue . Did you change the wires with the plugs ?
 

·
Registered
Joined
·
11,142 Posts
here’s my thought... if it was a 302 but they said it’s a 289, the firing order is of a 289. If the firing order is of a 289 but it had a 302 in it it probably wouldn’t even fire up right?
It would run with the wrong firing order
 

·
Registered
Joined
·
183 Posts
subscribing
 
1 - 20 of 20 Posts
Top