Whatever happened to the list rules about posting in plain text and trimming your posts. Have we totally given up? I'm in digest mode and a lot of my recent digests have been 80% coding crappola. Yes Ken you're right, speeding up coolant flow doesn't fix overheating problems. When lunkheads are skeptical (not uncommon when you work at a junkyard) I demonstrate with the torch test. Wave your hand through an oxy-acetylene torch flame. Do it FAST. No problem because there's not enough time for heat transfer. Now ask the customer to wave his hand through the flame slowly. No one has taken me up on this yet! As another poster said, another common misconception/mistake is to remove the thermostat to "solve" overheating problems. The cooling system is design with the restriction provided by the thermostat in mind. Remove it and flow increases and may follow wonky paths. The result is hot spots and sometimes cracked parts. Usually heads because that's where the heat is. Pete in PA From: "Ken Lang" <ken@xxxxxxxxxxx> Subject: RE: IML: water pump pulley diameter? Date: Wed, 13 Dec 2006 17:58:26 -0800 I might be jumping into this one a bit late. But I recall back when I had a 68 New Yorker (440) with AC that the water pump impeller was different for AC models verses non-AC models. I'm sure it had to do with the flow rating. Oddly enough the one for AC models had a smaller diameter impeller. That got me to thinking about the theory behind what Chrysler engineers were doing. All I could figure was that if you slow down the flow rate it has more time to spend in the radiator where it can remove the maximum amount of heat. If the radiator is sized properly it can remove more heat than the engine can create in the same amount of time. Then it becomes the job of the thermostat to constantly vary the opening and control the flow rate to the radiator. I've seen where people have installed high-flow water pumps to deal with overheating issues only to make it worse. Coolant must spend enough time in the radiator so it can remove the heat. Faster water flow doesn't usually fix overheating issues. IMHO ----------------- http://www.imperialclub.com ----------------- This message was sent to you by the Imperial Mailing List. Please reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be shared with everyone. Private messages (and attachments) for the Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm