Ping!

[HammerDown]

Can't seem to dial out a little annoying PING on a hot ad day with the AC on. (1981)
Using Premium Gas, moved timming around some, new plugs and wires, re-built the heads about 8000 miles ago.
Dosen't really to it when water temps at 200...but any higher ping,ping,ping,(with the AC on).
Any ideas? Thanks.

 

[MrGibbly]

Are you sure its a "ping" in the sense that it is coming from your engine and not some noise that the A/C compressor is making? My A/C compressor would run nice and quiet when I first started the car but once it got warmed up it would make "clanging" noises. I replace it with a rebuilt one and the noises stopped...still doesn't blow cold enough for my taste however.

 

[HammerDown]

Are you sure its a "ping" QUOTE]
Oh yea, I'm well aware of this dreaded noise .

 

[JohnZ]

Some combination of reducing your base timing and/or slowing down your centrifugal advance curve will dial it out - you'll have to experiment. Have you "mapped" your advance curve so you know what's in the distributor now so you know which way to go with it?


Edit: Oops - don't know if you still have the computer-controlled distributor or not, or whether you have a knock sensor.

 

[HammerDown]

Hmmm, no knock sensor on 81's. I tryed to back up timing at the distributor some. But the Computer actually controls it. "maped advance curve"> I don't think thats possible in a 81:confused

 

[JohnZ]

Yup, I guess you've got the first-generation computer-controlled distributor; never worked on one of those. You may not be able to alter the advance curve, but you can read it (and "map" it) with a dial-back timing light so you know what it's doing; if it doesn't make sense, you may have a wiring, connector, or ECU problem that's causing it.

 

[HammerDown]

Thanks for the feedback....