cooling fans - high capacity?

[rbkinstrey]

My 66 has a cooling issue when standing at idle - gets to 235 degrees within 5 minutes. When moving the engine temperature is mid gauge (210) or less.

I have replaced the radiator, now a new date coded DeWitt, new water pump, new thermostat, new vacuum advance and gauge is reading correctly. Car has Vintage AC system and an electric cooling fan. I have replaced the original fan and clutch with a Flex-a-lite 7 blade unit. Now significant change in cooling.

GM originally supplied 327/300 engines with a 17 inch, 5 bladed 25 (?) pitch fans. AC cars came with a 18", 38 pitch fans - will the 18 inch fan a fan shroud designed for a 17 inch fan with out rubbing when the engine moves? Would a 17.5 inch fan, 38 degree pitch fan design for a 427 work better - may not rub against the shroud design for a 17 inch fan!!??

Earlier , 63 - 396, used a 6 bladed 17.5 inch 38 degree fan.

What fan would be best to keep the engine cool while idling??? I don't care if it is a correct fan, I just need to cool off the engine at idle. Anyone know of the cfm capacity of the various fans?

Thanks

Bob

 

[LLC5]

I don't have the CFM for your fan questions, but I have seen heat extraction significantly improved by sealing the fan shroud (your post said that you do have one I believe, if not you need one) to the radiator with foam or similar compatible material. If there is an air gap between the shroud and radiator, the fan cannot pull as much air through the radiator as it is capable of resulting in higher coolant temps. Good luck with it.

 

[rbkinstrey]

shroud

Thanks
the gap around the shroud / raduiator has been sealed.

 

[Tom Bryant]

I see you said you also have an electric cooling fan with the Vintage A/C. have you checked the operation of that fan and at what temperature it comes on?

Have you checked to be sure the radiator core is full and there is no air pocket?

Tom

 

[rbkinstrey]

I see you said you also have an electric cooling fan with the Vintage A/C. have you checked the operation of that fan and at what temperature it comes on?

Have you checked to be sure the radiator core is full and there is no air pocket?

Tom

Yes the electric fan is operating. Initially after rebuilding the engine the radiator system did burp, but hasn't since.

People keep telling me I need to focus on the timing and carb rather than the fan. Any comments to this solution?

thanks

 

[Tom Bryant]

Retarded timing and/or a lean mixture will put a lot of heat into an engine.

 

[Tom Bryant]

John's article in the Knowledgebase is a good read on the topic. You can get an IR gun fairly cheap at Harbor Freight.

 

[LLC5]

John's article in the Knowledgebase is a good read on the topic. You can get an IR gun fairly cheap at Harbor Freight.

That is a good article, a must read from front to rear.

 

[Tom Bryant]

Here's an engineering service letter, also found in the Knowledgebase, that deals with overheating at idle. The subject is a 427 but the smaller water pump pulley and top seal might be something to look at.

Tom