[69birdboy]

I am having a strange detonation problem. I've never had detonation before.

Above about 4000 rpm and at full throttle, I am getting quite a bit of detonation. I haven't changed anything since last summer, and am still using the same premium gas.

I like the way it runs at part throttle, but want to get rid of the detonation at full throttle. What should I do?

[79firebird_99TA]

Originally Posted by 69birdboy

I haven't changed anything since last summer, and am still using the same premium gas.

Is it the same gas?

[69birdboy]

No, I've been driving it year round, the gas has been changed about once a week.

I also checked the plugs, and they look good. Just checked the timing, and it's right where I set it last summer.

[getmygoat]

Does the problem go away if you retard the timing slightly?

Did you quiet down the car in some way - for example, did you replace the exhaust system with quieter mufflers, etc?

[Malky]

Running hotter will cause this. Temp still the same?
Also running lean - fuel filter plugging, that kind of thing.

[455_regal]

springs in the distributor stetched-loose, letting it advance too much

[69birdboy]

Originally Posted by getmygoat

Did you quiet down the car in some way - for example, did you replace the exhaust system with quieter mufflers, etc?

Nope.

Originally Posted by Malky

Running hotter will cause this. Temp still the same?

It's running at a good temp. It didn't show up until the weather warmed up a bit, though.

Originally Posted by 455_regal

springs in the distributor stetched-loose, letting it advance too much

That's possible. I did use one of those mr. gasket advance kits in it, and those have a bad reputation for springs wearing out, but wouldn't the stops still stop the advance at the same total anyway?

[steve]

my vote is for leaning out under WOT or extended high rpm driving (highway)....

crimped/blocked fuel line
clogged filter
dirty carb

did the car sit over the winter ?

[69birdboy]

You may have been right about the filter. It was almost black with gunk. We'll see if that helps. Also, the car did not sit over winter.