Hey there! Any chance this was ever resolved or figured out? I've got a 1956 Super 88 that sounds like it's having a similar problem although it's becoming more consistent. The main characteristics are:

* Kind of an irregular ticking / tapping sound that sounds like it's coming from the back of the engine (I can feel the reverberations from it through the floor on the drivers' side)
* Happens only on acceleration
* Seems to only happen when the transmission has just shifted into 2nd or 3rd

This sound is somewhat hard to capture on video since it only happens while the car is going above probably 25-30 mph (but below say ... 50 mph) and only when I'm accelerating. I was thinking maybe I could tape my phone somewhere down there and drive around but I'm a little worried I'll never find my phone again ... Maybe I can figure out how to do it with zip ties hmmm ...

Anyways, any help on this would be appreciated! Thanks!

 

I moved your post to a new thread. You'll get more replies this way.

Your problem could be an exhaust leak. You can use a mechanic's stethoscope or length of vacuum hose in your ear to see if you detect the tapping with the engine idling.

 

What octane fuel you running ? Hopefully not 87

 

I'm running the best gas I can get which is usually 93 octane around here.

I managed to figure out a setup where I could capture the sound in a video. In case anyone else stumbles on this thread and is trying to do something similar, I just used the headphones that have come with iphones in perhaps the past 10 years or so that have a little microphone built into them. By taping it horizontally to the bottom of the door and then running the cord back up through the drivers side window, I was able to plug it into my phone and hit record while driving at speed to get the sound.

 

Sounds like lifters

 

Huh, interesting. So, there definitely is a regular lifter tick that the engine is making (that's another issue that maybe I'll be asking advice for here in the future ). The thing that's weird about this one is that it's not rhythmic at all. Just an irregular click / tick that you should be able to hear in both of those videos. Now that I look at them again, the lower speed one is perhaps slightly better since there's less wind and traffic noise. The other thing is that the noise is coming from the back of the engine, as far as I can tell and the louder ticks I can actually feel through the floor. Would that still indicate lifters to you?

Oh, and another thing that's super strange is that the only symptom here is the sound. There is no effect at all on how the car drives. I just had the carburetor rebuilt and it's actually driving really great now. It seems like if this was exhaust related or something related to combustion in general, I'd be able to tell just by the way it's driving, right? And if it was the transmission, I'd hear more of a grinding sound and it would effect the way the transmission is shifting? Could this maybe be related to a damaged or loose flex plate?

 

When I rebuilt the 394 in my 64 98 I found that there was a damper plate bolted to the flywheel. The male input shaft of the transmission mated into the damper plate. I found that there were numerous springs in the damper plate that were broken. If your Oldsmobile has a similar damper plate with broken springs maybe you're hearing them rattle around before or after a shift.

One of our other members could verify whether or not the transmission in your Oldsmobile uses a similar damper plate.
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I've got the service manual and there doesn't seem to be anything indicating a separate damper plate in the transmissions cross section diagram or the Torus Assembly diagram. Also reading through the assembly and disassembly instructions doesn't really seem to indicate anything like that. Then again, I guess it could have been taken for granted that it was there and you just didn't mess with it?

 

No one has figured out if he has a Hydramatic or Jetaway transmission yet. If its the original trans mission, I assuming it should be an early Jetaway transmission. Right mow, everyone is guessing. Charlie Jones will have answers.

 

Yeah, 1956 was the first year for the Jetaway and it’s the original transmission.