Another Cooling Subject

[73EStroker]

Got to start this thread new so as not to hijack on to another. My situation is that I have a welded aluminum x-flow 26" rad in my 73 chally. I have a real big 19" viscous coupling fan (clutch fan) 180* thermostat.  My engine will never overheat at idle at any temp and the last time out it was 105*. Last day I was out I travelled the highway around 75mph at 2100RPM in OD (A833OD) got to town burned around a little then visited a friend in town. While there the engine heat soaked just before shutting down and was borderline below boiling (just pushing some liquid out the overflow). Sat for 15 minutes and away I went again suffering vapor lock all the way home. Aluminum heads/manifold with fuel recirculation from carb back to tank with 1/16" restrictor. I have no shroud but that fan pulls mountains of air through and there are 3/4" gaps at the top and bottom of the rad that need filling with an aluminum shroud filler plate. The only other thing I have are open scoops in the rally hood. Aslo the fan is a bout 3/4" away from the rad. So if anyone can offer suggestions or confirmations that I am on the right path I would be appreciative. Firstly CP says I should get my engine advanced as much as possible as we have never set it properly since first startup, I should get the low speed richness running fixed and the radiator gaps sealed and I thought if I need to block off the hoodscoops to prevent turbulence in the airflow beneath the hood or not. I also purchased a heat shield and insulator for under the carb. Any other suggestions from the list members?

[farmertan]

My dad just solved his over heating issue in his 63 impala 409, got the engine hot and shut it off then tried to hand spin the clutch fan and it spun too easy (not locked up) bought a new one and the car ran 180 all day even in stop and go traffic. But he also ran the exhaust cut outs open more than he normaly does and I think that helps get rid of a lot of heat running open headers. He was hitting 200 220 in stop and go so it looks like that was the problem.

[Chryco Psycho]

heat soak is different to cooling effectiveness , when the engine sits after being run the alum heads can draw a lot of heat up into the heads / intake & ultimatly the carb , running a secondary cooling system with an electric water pump & electric fan can help to prevent this after shut down

[73EStroker]

I did not think about checking the operation of the viscous clutch  But will get the other fixes done this weekend as well. Neil - what was the part numbers for the fan and clutch I picked up at Lordco for you? I might buy a new one anyway.

[dodj]

The open rally scoops could be a part of your problem. They were for me. With the scoops unblocked, my 440 would run significantly hotter. Plugged as per factory - no problem. My theory is - with air coming in through the scoops, somewhat pressurizing the engine compartment, the fan cannot pull as much air through the rad.   

[Chryco Psycho]

You should be able to get a stock replacement clutch for the Chall , the one I ordered was the shorter one for the 69 & earlier applications . if the clutch is slipping it will limit cooling for sure but you are not heating up in stop & go in town so I think it has more to do with heat soak being drawn up into the heads After shutdown .

 I cannot see the scoops hurting cooling , , the heat is pushed back on the sides of the cowl & mostly under the car when driving , any air coming in the scoops would just force more air under the car

[brads70]