[rexs73gto]

I had that same noise in my car when I changed the fan blade to a flex fan trying to cool the car down. The fan blade when it would flex would come in contact with the pulley on the power steering pump. At idle it never made a noise but when I would rev it up the fan would again flex & again the fan would come in contact with the P/S pulley. I vote for the fan hitting something under the hood. When you changed the timing chain did the fan go back on the same exact way or is it maybe closer to something, or did you leave out a spacer or ???? I vote fan blade.

[tom s]

With my judge the fan would hit the bottom of the shroud.The frame was pushed up where the X member bolted up.Found out very common as people would jack up the car at that location.Caused the back of the trans to be too high and the front too low.Tom

[Bet Winner]

It does not sound like an internal engine noise to me.

I am posting about running 89 octane. I have no idea how you can run 89 octane in a stock 10.75:1 engine with stock timing. I use 93 octane alcohol free gas with lead added to it so I suggest a fuel upgrade if possible if you have a stock engine.

[dataway]

Certainly doesn't sound like anything internal to the engine to me. Way too slappy, scratchy sounding to be internal ... which would be a clanging, knocking, deep squealing sound.
I vote for fan or flex plate too.

[coonhunter70]

Yep, starter, flexplate, fan or converter dust cover.

[Jay69GTO]

Last night I was able to rule out the fan by taking it off and driving around without it (briefly). I was still able to recreate the noise. So i started draining the gas into 5 gallon cans. Tonight, I will dig into my manuals and get under the car to cgeck for loose bolts or cracked items.I must say i am pleased that there appears to be a consensus that it is not engine related.

[Jay69GTO]

Originally Posted by Alanjnc

Here's a dumb question, and I don't mean to insult you, but if you changed the timing chain are you positively sure the cam retention plate is in place?

I think you can see it in the attached image, underneath the bigger gear.

Also, no need for apologies. Better to be an idiot with a GTO and receiving free advice than pretty much anything else.

[ts3189]

if the new starter was recently installed as you said ,and that was the only change in conditions I would look there first.

[north]

Everything leads to pinging except the comment about it doing it when the engine is cold.

What is your carb situation? maybe running lean on the primaries (dirt, wrong jets etc) or into the secondary circuit.

Very unlikely its piston slap, that would be far worse cold, flex plate would be my second guess, loose bolts, cracked weld but sure sounds like pinging

[Jay69GTO]

Originally Posted by north

Everything leads to pinging except the comment about it doing it when the engine is cold.

What is your carb situation? maybe running lean on the primaries (dirt, wrong jets etc) or into the secondary circuit.

Very unlikely its piston slap, that would be far worse cold, flex plate would be my second guess, loose bolts, cracked weld but sure sounds like pinging

If it were ping, wouldn't the sound be timing dependent? Whether at 5 degrees or 12, the sound persists. Also, heavier distributor springs, and removal of vacuum advance appears to have no effect. Are pings generally that loud and close together? On researching engine ping in other forums and videos, it appears to be a milder ticking noise that is present at all RPM's and at idle. My loud noise only occurs at low RPM, under load, and disappears above 1500-1800 RPMs. Let me know what you think.

P.S. I am going to try better gas anyway. If that is the answer, I will be happy either way.

[north]

Yes and no, if you are running really low octane gas and/or you have a severe lean situation it will ping and sound like that.

When you cruise at a steady speed are you feeling any kind of surging? which would indicate lean operation. All it takes is a speck of dirt or a shred of gasket getting into a primary jet.

[Jay69GTO]

Originally Posted by north

Yes and no, if you are running really low octane gas and/or you have a severe lean situation it will ping and sound like that.

When you cruise at a steady speed are you feeling any kind of surging? which would indicate lean operation. All it takes is a speck of dirt or a shred of gasket getting into a primary jet.

I have no problems at cruise or any RPM above 1500-1800.

[TedRamAirII]

Check that flywheel. I wonder if the starter gear is hitting it.

[Jay69GTO]

Originally Posted by TedRamAirII

Check that flywheel. I wonder if the starter gear is hitting it.

Yep. That was it. One free shim in the starter and the noise is gone. Thanks everyone for all the suggestions.

[dataway]

Excellent ... hope my future problems solve so nicely

[north]

Glad to hear it worked out but given it wasn't always happening I'd carefully check the bell housing and flywheel to converter bolts to eliminate the possibility that you have some unwanted movement between engine and trans.