Pulley Diameters

4spdragtop said
Ok a few questions. I'm having heat/cooling issues.
Here is a pic of specs from my 67 manual.
I see the ratio is slightly different. My questions,
1. Isn't the ratio(fan:crank) meaning the fan pulley is bigger than crank pulley?
2. C, what size pulleys did you decide on?
3. Wouldn't a larger pulley speed it up, as opposed to the smaller pulley?
Thanks

View attachment 1715194010

1. The ratio is the number of revolutions the water pump pulley makes for 1 revolution of the crank pulley. For an AC car, 1.3:1 means the water pump pulley is smaller, and turns 1.3 turns to every 1 turn of the crank pulley.

2. Think it’s 5.75 and 6.5” at the moment.

3. No, a smaller pulley speeds up the water pump, it’s the driven pulley. It has to make more revolutions to keep up with the larger crank pulley.

6pk2goDemon said
I drove my car on Saturday for an hour around 11am--95*+ outside temps. Approximately 45 miles total including 32 miles on the freeway @ 60-65 MPH. It very slowly moved up to 210*....Awesome!! Then the last few miles the temp gauge climbed again to 230* :BangHead:

Shut off the AC & kept driving until the temp lowered--which it did.

Time to try out that 7.25” crank pulley!

4spdragtop said
Does engine rpm change when ac compressor kicks on? I wonder if compressor is not spinning at same speed?

The engine rpm will drop because spinning the compressor adds load to the engine. It takes horsepower to spin that compressor. And it spins at whatever speed the pulley turns. If it doesn’t, either the belt slips or the clutch burns up.