[LKLusza]

Hi Folks,

Here's the setup I currently run on my '70 400cu, auto trans and AC equipped GTO:
1) FlowKooler Cast iron HP water pump w/ tightened clearance to new SS divider plate.
2) US Radiators 4-row DesertCooler brass/copper rad with "High Efficiency" option.
3) Factory AC shroud
4) 7-blade 19" AC Clutch fan (I think it's factory- can anyone verify?) PN: 9796134
5) Hayden 2747 HD fan clutch
6) Stant 180 degree t-stat w/ bypass hole drilled in flange.

During the recent severe heat wave we experienced here in NE PA, I had an issue where the car started to run hot while stuck in traffic w/ the AC on. Temps went quickly from the usual 180-183 degrees up to 223 at which point traffic started moving again. I suspect that it would have continued to rise had I sat still longer. Temps very quickly returned to normal with any forward motion of about 15 mph or more. This leads me to believe that it's an airflow issue rather than capacity.

As a test, I switch the 2747 clutch out for the Hayden 2797 Extreme Duty unit. When mounted with my Pontiac fan (9796134), the thing refused to disengage. It whistled like a Chrysler Turbine car even on a subsequent 70 degree day. It just wouldn't disengage. Could it be that that Pontiac fan blade doesn't have enough pitch to make the clutch work properly? If not then what fan could I use?