[64-3Deuces]

Jack P.
Thanks for the info. My 64 GTO used to run hot/overheat with the original 389, water pump, radiator, clutch fan and no shroud. The original engine long gone (before I knew their worth) and was replaced with a with a complete 68 400 WT with the OEM non-clutch fan. I used the original radiator and had no cooling problems. Engine rebuild is a way off but always good to get info from members for future reference.

[Stuckinda60s]

Originally Posted by 64-3Deuces

Jack P.
Thanks for the info. My 64 GTO used to run hot/overheat with the original 389, water pump, radiator, clutch fan and no shroud. The original engine long gone (before I knew their worth) and was replaced with a with a complete 68 400 WT with the OEM non-clutch fan. I used the original radiator and had no cooling problems. Engine rebuild is a way off but always good to get info from members for future reference.

Do you mean the HO's stainless flex fan? That was an excellent fan and I remember reading an article where its power consumption was actually as good or better than the clutch fan. My '64 Goat with a 412, 4-speed, ran at 190-195 with the late style water pump, no shroud and the large (2-5/8"?) factory radiator. This was with 3.55 or 3.90's. It ran 12.80's at 109 in the early 80's.

I had clearanced the water pump impeller, but at the same time, had milled half the blades off the cast impeller to reduce the power consumption at high rpm's. That was something I saw in one of those magazine articles of tips. They said that Wally Booth had reclaimed 25 hp at 6500 rpm in his AMC by doing that and they said that cooling could actually be enhanced by doing it. I didn't seem to have any adverse effects by doing it. I still have the pump on one of my engines, a 455.

[64-3Deuces]

Yep, it was the HO engine with the OEM stainless flex fan and used a spacer between the fan and pulley. It would would run at 195-200 degrees. Back then I didn't know about the divider plate to impeller clearance but that will certainly be checked during the rebuild. I read about modifying the vanes but don't think I'll need that for the cars intended usage. Still have a lot of body work ahead first before I get back to the engine.