Hello, I wanted to read all the replies to this lenghty post before replying myself. It's taken me awhile, but I wish I had seen this post earlier on in my engine temp lowering quests. I have a few questions. I had a NAPA reman pump in my '66 GTO, that I bought in '96 when I rebuilt the engine. I didn't start driving it 'till last summer when resto was done. She always ran 210-220 on very hot days, then boiled out when shutting it off. And that's with no tstat. This winter I bought a good used timing cover, and another pump from NAPA...this time it's a "new" not reman pump. It does have a cast impeller. I had it all back together when I read this post. So, I decided to pull the pump off, and sure enough, the vanes were at least .25 from the new Ames backing plate. I smashed the plate down to almost touching, and had to reform it so it sat flat around the outer perimeters as well. Now, back together, it runs 180-190 on hot days, and after some timing enhancements, it runs great, and only hits 210 after hot soak. I can live with that. However, it does not have a tstat in it. Should I be running one to slow the flow rate down, and give the rad time to cool the water? And, did the factory impellers that fit the plates correct, have a tapper from the outer edge of the impeller to the inner? I'm running a 15lb cap, is that what is right? Every thing is new...four core rad, 7 blade fan and clutch, stock 389 no ac, Cal emissions. Sorry long post...I still have more questions.
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