Detonation + High Temp

[richd]

I've been reading some previous posts concerning detonation and cooling system troubles, but need some clarification. Should the top of the radiator be hot when engine is at least at normal temps? Mine is cool at the top and only starts getting hot if I feel the fins about 4 or 5 inches down the front or where the inlet hose attaches.

When I got the car (89 LX 5.0) ~2 months ago the temp guage read just below midway and detonation occurred during moderate throttle. Now the temp guage regularly hits midway and even approaches the next marker. Detonation occurs at even light throttle now.

The plugs look ok (Autolite Plats #25) I think. The gap may be a little big, but I didn't have a guage handy to check.

I can't accurately check the timing due to a lack of balancer markings. However, I have made a few counter clockwise adjustments to the distributor to try and retard the timing a bit. Is that the correct direction?

BTW, I'm running 93 octane right now (I used 87 once by mistake and cringed every time I accelerated). Even has problems with 94 octane (Sunoco).

Sorry for the long post and thanks for helping,

Rich D.
Bone Stock 89 LX 5.0