Crusader 270 1985 overheating

I HAVE A 1985 CRUSADER 270 CAR

I HAVE A 1985 CRUSADER 270 CARBURETED THAT OVER HEATS AT AN IDLE ONLY. RUNNING TEMP IS 185 TO 190. THE PORT ENGINE RUNS AT 160 TO 165. INTAKE CLEAN. NEW SEA PUMP. ENGINE WATER PUMP GOOD. NEW RISERS. NEW T STAT. HEAT EXCHANGER ACID DIPPED. COOLANT SYSTEM CHECKED FOR CO LEAK. WHEN IT OVERHEATS IF I INCRESE RPM TO 2500 RPMS IT COOLS OFF RAPIDLY THUS MAKING ME BELIEVE THAT IT IS A FLOW PROPLEM. ANY CLUESWOULD BE APPRECIATED.

"Mike, make sure that the raw

"Mike, make sure that the raw water and the coolant flow through the heat exchanger in opposite directions. Stu"

"MC A raw water pump uses a ru

"MC A raw water pump uses a rubber impeller. Its a displacement pump at low rpm's and centifical at high speeds. Double check RWP impeller, try another new one save old one as spare. Next pull hose from RWP discharge/heat exchanger inlet.....see if and how much water flows at idle. Look for a water flow diagram and get back to as original as possible. On my crusaders RWP discharge..goes to...transmission fluid cooler, engine oil cooler, heat exchanger, then to riser and out. Make sure RWP drive belt is tight and not slipping at idle. Good luck keep us posted...Ken"

Pull the discharge line off th

Pull the discharge line off the RW pump and start the engine. Note the water flow and see if it is flowing properly at low rpms. It sounds like that new pump may have an issue.