84L69TA

Something happened to my Trans Am last night. I was getting on it a little bit last night and all of a sudden it just started pinging really bad at anything over 3500 rpms. Its running cool, plugs look good, no loss of coolant of oil so far. Oddly enough, it seems to have more power now, but its just pinging so bad. 1st gear isnt noticeable, 2nd starts to get pretty loud, and 3rd and 4th is ridiculous. My timing is still at 9-10*. I pulled the plugs after a WOT pass and they look fine. Also, the carb is roaring louder than ever. It totally drowns out my 3" exhaust and Flowmaster. I tried 91 octane and even added octane boost. The motor is an LG4, Edelbrock headers, and 3" all the way back, XE256 cam, G hanger and DR rods. Same as its been for 6 months. Do these symptoms ring a bell as to what may have happened? Please help, I dont want to do any damage to this motor as its my daily driver. Thanks in advance all.

84L69TA

By the way, the car only has about 84,000 miles on it.

ZZ28ZZ

A knock sensor dying would explain sudden pinging and more power since it's not telling the computer to decrease timing.
Don't know if a dead sensor would make computer send a code.

I saw some info abt reading plugs on one of the spark-plug manufactors web sites (don't remember which one).
Might wanna try a search for "plug reading".

To see the evidence of detonation, you pretty much need a magnifying glass.
Look for very tiny pieces of aluminum (from the piston top) melted to the spark plug electrode.

If you have to drive it, you should probably back the initial timing off till it stops pinging. Cast pistons won't survive long when subjected to severe detonation.

84L69TA

Well, its an 83 LG4 car, so it dosent have a knock sensor. But ill back the timing off a little bit and see how she runs.

Mr_Happy

Do a Compression check. I had a head gasket blow between 2 and 4 it pinged like that because the next cylinder was pre-firing the other.

ZZ28ZZ

Oops, my bad on the knock sensor.
Have you checked the total advance on the timing?
Does your dist have mechanical adv?
Maybe a spring came off and it's advancing too soon.

84L69TA

ZZ28ZZ:

I still have the CC Q-jet and CC distributor. Would it have springs inside it? Thanks for the help though...ill look a little deeper into it.