OK, let's recap the problem for those who haven't followed this problem through last summer:

My '64 PV544 with B20 engine and BW35 trans had a bad habit of running hot. At least that's what the original Volvo gauge was telling me. This would happen when idling in traffic or climbing grades.

The Volvo gauges seem to be 'pessimistic' to me; the temp gauge shows the engine running hotter than it does, and the fuel gauge says I have less gas than I actually have.

I boiled out the radiator and refilled with 50/50 ethylene glycol antifreeze, then I installed a 170 degree thermostat. The PO had a 190 installed.

I gained a little ground, but still the gauge would climp to the HOT end while idling in traffic.

Next, I ditched the scrawny 4-blade original Volvo fan for a 6-blade Flex Fan.

This got me through the tail end of last summer, and through the winter (naturally!)

I know that if your ignition timing is reatrded too much it can cause overheating. I checked mine, and it was off a little, but not that much. I set it at 20 degrees BTDC and the car certainly ran better!

This past weekend was relatively hot, temps in the 80's. I drove over to Barstow for a car show (about 93 miles each way) and discovered that unless I was driving into the wind, the gauge would go right up to HOT again.

Turn the car so it was moving even slightly into the wind, and the temp would drop immediately.

There are two more steps I can take: One would be to install the fan shroud I started to make last summer, and the other would be to buy and install a pair of electric fans on the front of the radiator.

I just came back from the parts store, where I got a jug of Water Wetter, which is supposed to increase the heat transfer ability of your coolant. I'll drive with that in the system for a few days and see what it does.

Any thoughts or suggestions?

Steve