Can someone explain pinging and knocking (are they the exact same or slightly different?) and what they sound like?

The other day I heard a sound while driving up a fairly steep section of freeway at 70 MPH, it kind of sounded like someone rubbing a couple of quarters together furiously. Now I've started to notice a similar sound (but far less intense) as very low speeds, say 20-35 MPH, while driving.

My timing is was set at 9° BTDC however after that unnerving experience I have set it back to TDC. However the sound at low speed hasn't changed, and I drove up the same stretch of road but now my car is hard pressed to reach 70 MPH at that grade.

Did a test after I got home, put the car in drive with the e-brake pulled nice and tight. Revved the engine and could hear the odd sound. It seemed to be coming from the carb and reverberating through either the tube that runs to the crankcase vent valve and/or the breather cap tube.

One last thing about the sound, it sounds sound like I'd expect a ping to sound like, and maybe more like air being forced through a small metal opening or something.

Disclaimer: I am almost positive that my vibration dampener has slipped, but I'm not sure how much (tips on finding TDC with the head on and engine in the vehicle, etc`?).

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'66 Dodge Dart

Pinging under load can be a light sound not necessarily a hard knock. It is easy to do with a stock motor, a 904 and 2.76 gears up a hill or during high speed passing or climbing a long grade like the one north on I-5 to Mt. Vernon.

You may have to verify where your TDC on the damper by pulling the number one plug and putting your finger in the hole while some one bumps the engine over......just unplug the coil first.

Is your motor stock?

My 74 was a real slug and would ping no matter where I set the timing on some hills. After the rebuild, compression increase, cam advanced, distributor recurve, mild porting, 2.25" exhaust, removing the exhaust deflector, porting and enlarging the exhaust manifold, it doesn't break a sweat...

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Pinging and knocking sometimes are used interchangably...the sounds you typically get from detonation from the timing not being correct, lean fuel mixes, and/or using the incorrect octane.

Pinging used to be described as a rattling like you hear at the top end of a diesel truck note...that 'rattle'...if your timing is very off, and you're running low octane as you accelerate you can hear a 'rattle' or 'pinging' sounds which may go away as the proper amount of timing comes in, more gas is used to richen the mix and cool the chamber, etc...

Knock would sometimes be described as the sound like someone was using a hammer inside the engine to 'knock' on something (usually a piston being beat on by premature detonation of the air/fuel in the chamber due to timing or a 'hot spot' of carbon lighting it off, or the rod on the bearing if the tolerances are too loose.

Don't drive it too long that way, usually pinging can lead to a hole in the piston...knock can have other serious effects as well....

Take a moment to find TDC of #1, mark the balancer with a small bit of white out or shoe polish or white paint...then recheck your distributor settings....better to fix now and replace a $100 balancer than a complete $1200 engine rebuild....

-D.Idiot

Ok planning to check the dampener tomorrow...

The manual has a system to find 12° BTDC (could be ATDC can't remember at the moment) but its a long process involving removing the valve cover (which is hate doing). So the question is, is there a simpler way to find TDC?

Ted I see you mentioned jamming my finger in the #1 spark plug hole and feeling for it... but how to I turn the engine? Also, will I really be able to feel it? It seems like it'll be hard to jam my pinky that far down into the combustion chamber.

DusterIdiot, you say that lean fuel mixtures can cause pinging? I could see that as a possible issue. Assuming it is as issue with lean mixtures, would I need to change out the jets, replace the carb, or could it be simple as enriching the idle circuit (wishful thinking).

Also, yes the motor is, as far as I know, completely stock (apart from a later model BBS).

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'66 Dodge Dart

Josh, put some electrical tape over the end of a screw driver and then stick it down in the #1 spark plug hole. Use a helper or turn the fan with your other hand until you feel the piston reach it's peak. If your balancer has slipped, your timing mark should still be somewhere in the ballpark there. If the timing mark is all the way on the bottom of the balancer, then you're 180* out. So turn the fan again until you feel the piston go back down and then back up again. Now you should be on your compression stroke. Not every motor likes to be at 12* BTDC and some will ping there.

If you don't have a helper, sometimes it's best to remove all the spark plugs, that way it's easier to turn the fan with your hand.

If you pop the distributor cap and look at it from the passenger fender side, it should be pointing at about 3 o clock.

........check your PCV valve .....it might be the rattle you hear.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

ESP47, thanks for the tips.

Sandy, check it in what way? When placing my finger over the valve it gets sucked right in. It doesn't seem to be seated all that well in the valve cover, but it doesn't feel as though its rattling.

Today I drove it to the store and made some more notes about the sound. It sounds a lot like air, and less like a rattle. Its like a mix of quarters being rubbed together and wind rushing through a slightly openend fender vent. I'm starting to think it may not even be pinging...

I noticed something else on a drive today. The low speed sound is not produced at any specific RPM, but it seems more throttle position dependent. At low speeds the engine (and other road noise) is soft enough that you can hear it clearly. However, at higher RPM and higher speeds with the same throttle position the sound is also present, however slightly drown out by the sound of the engine and my worn out suspension.

Last odd thing about the noise is that it happens anytime the transmission is in gear and under any kind of load (uphill, downhill, flat pavement) as long as the throttle is in the magic zone. Also, the engine doesn't run rough and no loss of power when the noise is heard, just smooth and strong.

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'66 Dodge Dart

Check the air filter housing, intake preheat components, throttle and kickdownlinkages, oil dipstick, and anything else that's not "solidly" attached. All of these can rattle. With the transmission in gear, there is more torsional engine vibration, which might be at or near the resonant frequency of one of the above components.

Ken

Josh,
No you won't feel the piston. But when you have your finger over the spark plug hole when the piston comes up the compression will blow your finger off the hole. We timed a rig last weekend quickly to get a heads up where top dead center was in relation to the damper mark. Plugged in the distributor and aligned the rotor and it fired right up, then fine tuned it from there with the timing light.
Do you have a automatic transmission? Sometimes the tranny coolant lines will vibrate against something and cause a rattle at a certain rpm. I use 2 rubber hose clamps with a single bolt to clamp them together. That puts the two lines about 1.5" apart or so. I have a couple of pairs of them at different points. The rubber on the metal pipe clamps keeps them isolated and nice and quiet at all rpms.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I do have an automatic transmission. However, the sound doesn't seem to be RPM specific, and more related to throttle position, but I'll look into it anyway.

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'66 Dodge Dart

Just for the record, it absolutely was the PCV valve! Makes a combo hissing/rattling sound. Which would also explain my slightly less than perfect idle....

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'66 Dodge Dart

Wow I'm glad I read this thread. My car has been pinging for a while and I figured it was just my fuel filter rattling against the air cleaner. I had no idea it sounded like a rattle like that. Checked my timing and I was at about 15* BTDC. Dropped it down to 10* and now I don't hear it anymore.