How do I stop my 383 pinging ?

[71 Bee Man]

Hi guys,

look, up front I'm no mechanical guru - far from it.

The thing is, I've always been able to at least get my cars running right using the old timing light and tachometer, until now.

This is my first big block car - and it's got a 383 magnum in it. There doesn't seem to be anything special done to the engine, she runs tight and strong and is really reliable. What's annoying though is that I just don't know what to do to stop it pinging. I'm about to visit the local mechanic, because even though I use 98 octane fuel and have retarded the timing it still pings under load.

Last night I upped the advance and opened up the mixture screws a little - thinking I may have been running her too lean, but she still pinged under accelleration.

My next step was to use a new fuel we have here called Optimax Extreme which is at least 100 octane.

Anyone have any advice.....is it a normal problem.... anything ?

Sorry if the info is a little vague but I wasn't sure where to start. What else causes pinging ?

Peter
Sydney, Australia.

[myk]

Idle mixture adjustments only affect the car's idle.  If you need to richen up the running fuel mixture you'll need to increase jet sizes.  What kinda' 'carb do you have? 

Maybe excess carbon buildup inside of the engine has raised the compression too high?  Someone'll chime in here...

[71 Bee Man]

Idle mixture adjustments only affect the car's idle.  If you need to richen up the running fuel mixture you'll need to increase jet sizes.  What kinda' 'carb do you have? 

Maybe excess carbon buildup inside of the engine has raised the compression too high?  Someone'll chime in here...

From memory it's an Edelbrock 750. The reason I was adjusting the mixture was because I read that sometimes it needs more fuel, but I have a feeling you're right about jet size. Today I put 15 litres of this new fuel we have out here which is 100 Octane. I'll see how she goes. Still pinging a little on the way home (under accelleration or uphill), but seemed less - is that my imagination ? Have to wait for the fuel to filter through I guess, but she was pretty low when I put the 15 litres in.

[charger Downunder]

Are you using a valve lubricant mixed with the fuel like valve master etc. By the way have you tried using the plain uleaded its got 92 octain rating even when we had leaded fuel in Australia the octain rating wasnt high.I dont know what the octain level in fuel is in the states but i put my money on you need to lower the octain and try the plain unleaded with a valve lubricant added.

[tecmopar]

What is the total timing set at---full advance?

[71 Bee Man]

What is the total timing set at---full advance?

I originally had the timing set as per factory at 2 1/2  degrees BTC. Yesterday I bumped it up to around 7 degrees. It was till pinging at 2 BTC so I figured what the heck.

As for using 92 octane, I was always led to believe that pinging was a result of the octane level being too low. As for our ratings out here, I was talking to a few guys who knew a thing or 2 about fuel and they reckon our fuel in Australia isn't a patch on what they have in the U.S.

I do use Valvemaster with the fuel, but I don't think that has any impact on the pinging.

[deputycrawford]

You only gave us your idle timing. We really need to know your maximum mechanical timing and by what rpm does it come in.  Also, unplug your vacuum advance if you haven't already. It will add almost another 20 degrees. That will make you ping if your engine has carbon build up. Shorten your mechanical advance and set your mechanical timing to 36 degrees total. Unplug that vacuum hose and pulg the nipple. You will not need it.

[grouseman]

I agree with half of what the deputy says.  Find out first what your true mechanical advance timing is, when and how much.  You're shooting for around 34º by about 2,500 rpm, give or take.  Remember, measure that with the vacuum advance disconnected.  Report back, and then we'll analyze.  You may have spun the ring on your balancer, for example, in which case you won't get a true reading.  Make sure you're hooked up to the #1 cylinder, of course. 

[Blue Pentastar]

Hi just to clearify what do you mean by pinging. is it just when you accellerate. or does it make this noise at an idle. Does it get louder load or just stay the same. You don't by any chance have an exhaust leak do you. some times a small leak can make a noise similar to a ping.

Just my 

Mike Schrader

[71 Bee Man]

Hi just to clearify what do you mean by pinging. is it just when you accellerate. or does it make this noise at an idle. Does it get louder load or just stay the same. You don't by any chance have an exhaust leak do you. some times a small leak can make a noise similar to a ping.

Just my 

Mike Schrader

No, it's pinging, or detonation or whatever you want to call it. It happens under accelleration or under load. There's no exhaust leaks.

As for the mechanical timing, I'll muck around with it over the next couple of days. Would you believe I've never checked the "mechanical timing". I've always just set an idle timing and went from there. As I said in my initial post, I'm no master mechanic by any stroke, but I'll have a go and see what happens.

Peter

[deputycrawford]

Grouseman, I guess I shouldn't have put that sentence below into the thread. I should have elaborated more on that thought before I posted it. I do know that vacuum advance will come in at part throttle under light load. Check it sometime. It should read around 55 degrees with the vacuum attached at light load. I agree with you that he should check the mechanical and see if his balancer has spun.



"That will make you ping if your engine has carbon build up."