Detonation
 

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?

Is it the same gas?

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.

timing?
 

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?

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

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

Nope.

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

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?

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 ?

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.