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Cooling my new engine; H2O pump, rad?

324 Views 3 Replies 3 Participants Last post by  TNJeeper
I got my new engine back from the rebuilder this week; 401, bored .040 over, rv cam. Is it worth the money to go with a high flow performance water pump? The price difference is about $60 and I have read that sometimes moving the coolant through the block too fast can hinder cooling. Also what radiator will work good? Stock one or one of those pricey BeCool units? Finally what thermostat too run?

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Dear Denverdweller: It has been my considered opinion for quite some time; and corroborated by several other mechanics with an eye for engine design errors; that the AMC V8 family of engines is OVER BY-PASSED. That is to say that it recirculates too much water back to the block via the by-pass hose there in the front. Think of it:.....the Shev-Lay small blocks have NO by-pass at all; several other engines have by-passes, large and small, but NOTHING like what AMC has. My personal take on this is that the HEATER loop alone is enough.....that's what the small block Shivel-A's used in the NINE pickups that I've owned. Sooooooo what I would do if I wuz you is put a RESTRICTOR in that by-pass line and have just a 5/16" MAYBE SMALLER diameter hole....if even that. What works good for radiator hose sized restrictors is the PUSH WASHER from a 12 Ga Shotgun slug round.
I would also drill that thermostat to aid in getting the air out of the engine and into the radiator.......a lead-in-the-pencil sized hole.
I really believe that the problem is that the AMC engines were built to run WITH or WITHOUT a heater loop so the designers were afraid to restrict the by-pass in case there was no heater in the vehicle.....KNOWING that if there WAS a heater, less coolant would be diverted to the radiator. In the Sheevies we have the OPPOSITE problem, and that is TOO MUCH water going back to the radiator in the winter to get good warmup, soooooo we have a side-outlet-restricted tee in the heater return hose which sends the AIR to the radiator and most of the water back to the block so we don't freeze when driving in winter weather. Just ASK me about Chevy pickups.....been there, done it NINE times.
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