I am trying to help a friend sort out his 81 automatic lunging. He has the same engine as I do and at 800 RPM in neutral when you drop into drive it really squats down. I don’t know what it is but it ant fun to drive as is. My 4 speed is much smoother to drive even with a 900 RPM idle. As I said our engines are completely the same as he used my parts list when building the motor. Even the headers and side pipes are the same. Tried idling it down to 600 but it vibrates too much at low idle.

I am not into automatics so need some advice from someone that does.

 

Mine does the same thing. Idles fine and then squats in any drive gear. Just had the tranny rebuilt, and I've had the idle set all over the place. I could be completely wrong here, but my guess is worn out rear suspension.

 

Car has complete new suspension less that 1,000 miles.

 

Dean -what do mean not fun to drive? All autos squat a little.Off idle not responsive? Camshaft choice maybe.Dist. vac. can?

 

As I said his car is a carbon copy of mine except colors and the auto. My 81 is fun to drive idles a little high, smooth driving no vibrations.

 

Scratch that one, then

 

My '81 does the samething when you put it into drive, I don't mind it, though I would also like to know what causes it.

 

I had a 1980 Automatic. The car did that from the factory. I thought that was the coolest thing. I loved the way it squats down when it went into gear. I was told at the dealer the car does that because of all the ujoints in the drive line. When the load is placed everything tightens up in the drive line. I never noticed the rear end come up when you put it in park but it always went down.

That was the only good thing about an automatic vette. Here comes the flames

Enjoy

 

My 81 did the same thing when I had the original transmission in. It's not as bad with the 700r4, but it still does it to a lesser degree.

 

happens on my 82 all the time. i actually posed this question awhile back, and was told it was normal.

 

Just to clarify- this is not so much about the squat-its more about a vibration -like a stumble maybe ? Could a cam made to work with a 4 speed not work so well in an automatic? Could it be missing?
I have also run into some automatics that run better on ported vacuum than on manifold vacuum.Or is that the other way around.

 

Now that I hear that it is a common thing with the Auto, I am now working on getting all the rattles and vibrating things taken care of. First the side pipes were hitting something and the A/C compressor was loose and vibrating now I will attack the interior rattles, that will take some time.

Boy I am sure glad I have a 4 speed. Not only does the auto jump when pulled into drive but it is no where as positive as my good old 4 steed. I guess the saying that real Sports cars have stick shifts is true.

 

I would bet you need to reset the idle mixture and timing. Unfortunately if he is running the cc qjet I can't help except hook up a vacuum guage and adjust the mixture if you can. Same goes for the timing on that l81. I scrapped all of mine so this old dog didn't have to learn any new tricks.