[dataway]

Ok, I'm going off the deep end now (as if I don't have my own engine problems).

Extracted the audio from the video, ran it through a processor/editor.

Here is a 4 second clip .... this represents TWO SECONDS of the audio slowed down to 50% speed so it's 4 seconds long.

https://youtu.be/Vb2wNs5zQsU (just used a pic of my engine because you can't upload just audio to YouTube)

You'll count six pairs of clicks/knocks ... actually the full audio file exactly 2 seconds was 7 pairs. So we'll go with 3.5 pairs of clicks per second.

If Crankshaft related ... if each PAIR of clicks is a single event ... that would be 210 RPM - 3.5 x 60sec (unlikely). If each PAIR of clicks is two events that would mean 7 events per second, or 420 RPM still kind of unlikely.

Half Crankshaft speed (cam, exhaust, dist, lifter, timing chain etc.)
if each PAIR of clicks is a single event that would be 420 RPM
If each PAIR of clicks is TWO events that would be 840 RPM (more likely)

However ... obviously the clicks are not evenly spaced, you can hear them in PAIRS ... then a gap, then another PAIR. Sounds a lot like 2 out of 3 converter bolts tapping on something, but just doesn't seem fast enough to be crank related, or anything attached to the crank... that would be a steady, even click for every rpm. Engine sounds like it was idling at least 500 rpm. I have no idea ... maybe two cylinders leaking exhaust ... that doesn't seem likely. If I knew the exact rpm of the engine when the video was taken it would easier to narrow down the timing.

You will also notice, that in each PAIR of clicks, each click has a slightly different sound, again, what a person might expect from two different converter bolts tapping something ... but it's just not fast enough to be converter bolts I don't think. But ... with engine power pulses with each cylinder firing ... jeez, who knows what could happen with all that going on.

Below is a picture of the 2 second (expanded to 4) audio extraction from the last quarter of the video posted on page 11. Doesn't really tell you much as the clicks are kind of buried in the mix and don't appear to correlate with the spikes as far as I can tell. All you can really see is the quiet between Lopes of the the cam.

I should have been down in the shop working on my engine, but I spent a couple of hours playing around with this.

Update: Here is the sound slowed to 1/3 of original .... spacing of clicks sounds much more even. I time them about 0.15- 0.166 seconds apart. 360-400 rpm .... still too slow to be crank rpm ?
Don't let the lower pitch fool you into thinking it's a "Knock" ... it's not ... way more of a click.

https://youtu.be/hVk_SibKX0k

[JSPONT]

Originally Posted by dataway

Ok, I'm going off the deep end now (as if I don't have my own engine problems).

Extracted the audio from the video, ran it through a processor/editor.

Here is a 4 second clip .... this represents TWO SECONDS of the audio slowed down to 50% speed so it's 4 seconds long.

https://youtu.be/Vb2wNs5zQsU (just used a pic of my engine because you can't upload just audio to YouTube)

You'll count six pairs of clicks/knocks ... actually the full audio file exactly 2 seconds was 7 pairs. So we'll go with 3.5 pairs of clicks per second.

If Crankshaft related ... if each PAIR of clicks is a single event ... that would be 210 RPM - 3.5 x 60sec (unlikely). If each PAIR of clicks is two events that would mean 7 events per second, or 420 RPM still kind of unlikely.

Half Crankshaft speed (cam, exhaust, dist, lifter, timing chain etc.)
if each PAIR of clicks is a single event that would be 420 RPM
If each PAIR of clicks is TWO events that would be 840 RPM (more likely)

However ... obviously the clicks are not evenly spaced, you can hear them in PAIRS ... then a gap, then another PAIR. Sounds a lot like 2 out of 3 converter bolts tapping on something, but just doesn't seem fast enough to be crank related, or anything attached to the crank... that would be a steady, even click for every rpm. Engine sounds like it was idling at least 500 rpm. I have no idea ... maybe two cylinders leaking exhaust ... that doesn't seem likely. If I knew the exact rpm of the engine when the video was taken it would easier to narrow down the timing.

You will also notice, that in each PAIR of clicks, each click has a slightly different sound, again, what a person might expect from two different converter bolts tapping something ... but it's just not fast enough to be converter bolts I don't think. But ... with engine power pulses with each cylinder firing ... jeez, who knows what could happen with all that going on.

Below is a picture of the 2 second (expanded to 4) audio extraction from the last quarter of the video posted on page 11. Doesn't really tell you much as the clicks are kind of buried in the mix and don't appear to correlate with the spikes as far as I can tell. All you can really see is the quiet between Lopes of the the cam.

I should have been down in the shop working on my engine, but I spent a couple of hours playing around with this.

Update: Here is the sound slowed to 1/3 of original .... spacing of clicks sounds much more even. I time them about 0.15- 0.166 seconds apart. 360-400 rpm .... still too slow to be crank rpm ?
Don't let the lower pitch fool you into thinking it's a "Knock" ... it's not ... way more of a click.

https://youtu.be/hVk_SibKX0k

Damn nice work! Yes I tend to think converter bolts, or like I said before, flex plate bolts a little to long and sticking thru the back of the crank.

[400 Lemans]

I think its a leak at the head pipe where it is attached to the manifold. Sounds just like when the donut gaskets would start going bad on the older cars.

[Va68goat]

Bentwheelbob,
Well, theres no sense in being anything but patient. 6 months ago we checked for an exhaust leak. There is no evidence of an exhaust leak at the manifold. I know its almost impossible to tell on the videos but I don't think it's an exhaust leak. I've had some experienced guys looking at this car and they see no signs of an exhaust leak.

[Va68goat]

Well...there isn't much to report. Looks like I'm going to take the GTO to a local shop to replace the flexplate. This is a shop that is recommended from a forum member. I'm hoping that this is the cause for the knocking noise. I'm not too confident that this is the issue or not but I'm hoping. I'll have the mechanic pull the converter back and run the car to see if the noise is still present. If this isn't the issue, it's going to have to go back to Arizona!

The good news is..is that Jeff Koerner has been working on a carburetor for me since June and it should be here this week so I can get that on the car at the same time as the flexplate gets switched out..

[Squidward]

I can't believe Dataway's Audacity! The nerve of some people...

[dataway]

Originally Posted by Squidward

I can't believe Dataway's Audacity! The nerve of some people...

Pretty nice piece of software .. FOR FREAKIN FREE