63 409/425 running hot at idle

[FAZ]

Hey all,

I have a 63 409/425, dual electric fans and a 160-degree thermostat and a dual core radiator. While driving it runs in the 190-degree range, once I stop at a light the temperature quickly climbs to 220 and will drop back down to 190 as I begin to drive. My thought is that I am not pulling enough air through the radiator to dissipate the heat but wanted get some feed back from you all.

I started down the path of installing shroud but wanted to get other opinions before I proceed as I purchased a shroud and that I was told was for a 63 409 but it will not fit around the radiator which leads me to believe one of them is incorrect.

Should I be running a 180/190 thermostat?

Is there a way I can tell if the shroud is from a 63?

Does anyone know where I can find the radiator dimensions?

Faz

 

[GA409]

Can you post some pics of your radiator and shroud?

 

[MRHP]

What is your initial timing, and do you use a vacuum advance?

 

[FAZ]

Can you post some pics of your radiator and shroud?

Best I can do with the radiator pics

 

[FAZ]

What is your initial timing, and do you use a vacuum advance?

12BTC with
vacuum advance

 

[64ss409]

You should probably have about that much with vac advance disconnected.

 

[FAZ]

You should probably have about that much with vac advance disconnected.

Yes that is correct, 12 BTC with advance disconnected, I was not clear on that!

 

[62_Conv_2-4s]

remove the electric fan and its shroud. Install the stock shroud and a 5 or 6 bladed clutch fan.

 

[Toms63SSQB]

remove the electric fan and its shroud. Install the stock shroud and a 5 or 6 bladed clutch fan.

Worth a try, unless you have already done that.

 

[427John]

That cosmetic doohickey (its not a shroud) that the electric fans are mounted to is blocking air flow thru the radiator portions that aren't directly in front of the electric fans.

 

[327]

 

[FAZ]

That cosmetic doohickey (its not a shroud) that the electric fans are mounted to is blocking air flow thru the radiator portions that aren't directly in front of the electric fans.

I am aware that they are electric fans and not a shroud. As requested I posted pics of the radiator (in the car with the electric fans) and the shroud I purchased that I am having issues with it not fitting.

 

[427John]

The point I'm making is that with the electric fans with minimal strapping to mount them would be better than what you currently have, possibly enough to keep it cool, but I agree with the others a mechanical fan with "shroud" would be best. While a louvered panel may look cool it won't allow nearly as much airflow as nothing at all. The OEM "shroud" isn't really a shroud but a device to convert the mechanical fan into a ducted fan to make it more efficient, you can see that the area around the "duct" is also minimized to allow as much airflow as possible, a true shroud would be more of a device to redirect that airflow thru the fan opening, either should work but I prefer Chevy's ducted fan approach.

 

[FAZ]

The point I'm making is that with the electric fans with minimal strapping to mount them would be better than what you currently have, possibly enough to keep it cool, but I agree with the others a mechanical fan with "shroud" would be best. While a louvered panel may look cool it won't allow nearly as much airflow as nothing at all. The OEM "shroud" isn't really a shroud but a device to convert the mechanical fan into a ducted fan to make it more efficient, you can see that the area around the "duct" is also minimized to allow as much airflow as possible, a true shroud would be more of a device to redirect that airflow thru the fan opening, either should work but I prefer Chevy's ducted fan approach.

Got it and that makes sense. I am not a fan of the electric fans. I prefer the OEM look and to be able to enjoy the car without having to worry about overheating, thanks firvthe clarification.

 

[327]

I am running original shroud on my 327 with clutch fan. Car runs fine , no overheating.

 

[Ishiftem]

That shroud with the electric fans should be drawing air through the entire core. The problem I see is that the fans are mounted down low side by side. Most of the air is only being pulled through the bottom half of the radiator. They work better if they are staggered. Second problem are the louvers. If the fans are drawing air through the louvers that’s a problem. Third issue is the small openings of the fans. While driving they are a restriction. If the 190 is right with a 160 thermostat thats too much. It should run closer to 165-170. Lastly are the electric fans adequate. They may not pull enough cfm because of design or low voltage. It takes one really big high quality electric fan or two really good fans to equal the cfm that a big 5 or 6 blade mechanical fan can pull.

 

[SSpev]

That is a small block fan shroud. 3 rib vs 2. The mechanical solid mount fan is doing nothing.

That shroud with the electric fans should be drawing air through the entire core. The problem I see is that the fans are mounted down low side by side. Most of the air is only being pulled through the bottom half of the radiator. They work better if they are staggered. Second problem are the louvers. If the fans are drawing air through the louvers that’s a problem. Third issue is the small openings of the fans. While driving they are a restriction. If the 190 is right with a 160 thermostat thats too much. It should run closer to 165-170. Lastly are the electric fans adequate. They may not pull enough cfm because of design or low voltage. It takes one really big high quality electric fan or two really good fans to equal the cfm that a big 5 or 6 blade mechanical fan can pull.

This is all correct. the louvers have to be blocked off when the electric fans run to get their full affect. When the fans are off there need to be air flow- louvers open. they make shrouds that have flaps just for this. This setup is just all wrong. Sorry.

On a side note. With the mechanical solid mount fan and the SBC shroud, it might work. fan should hang out the back 1/2 to 1 inch to be effective.

 

[FAZ]

That is a small block fan shroud. 3 rib vs 2. The mechanical solid mount fan is doing nothing.

This is all correct. the louvers have to be blocked off when the electric fans run to get their full affect. When the fans are off there need to be air flow- louvers open. they make shrouds that have flaps just for this. This setup is just all wrong. Sorry.

On a side note. With the mechanical solid mount fan and the SBC shroud, it might work. fan should hang out the back 1/2 to 1 inch to be effective.

There is no need to be sorry I purchased the car this way. I brought this to the forum because my assumptions were that this electric fan setup is not correct and the reason I am looking to convert back to the original shroud.

Unfortunately I was told the shroud was for a 63 409 but it does not fit around the radiator.

My goal is to bring it back to it's original state. That said if anyone has a 63 409 shroud and radiator available I am interested.

 

[Murphdog]

There is one on eBay https://i.ebayimg.com/images/g/-8gAAOSw1vllYPVJ/s-l960.webp and it looks just like yours, you have the correct one now. I think the 3rd rib that SSpev is seeing is just the flared opening. The shroud mounts to the 6 same bolts that hold the radiator in. They are 27" across. This is the same on 6 & V8 cars. I looked at a shroud I have and it is the same. I have 2 of these. Without the mounting flanges/legs the round part is identical top & bottom. The mounting flanges determine top & bottom as they are offset vertically from the fan opening.
Jeff

 

[SSpev]

There is one on eBay https://i.ebayimg.com/images/g/-8gAAOSw1vllYPVJ/s-l960.webp and it looks just like yours, you have the correct one now. I think the 3rd rib that SSpev is seeing is just the flared opening. The shroud mounts to the 6 same bolts that hold the radiator in. They are 27" across. This is the same on 6 & V8 cars. I looked at a shroud I have and it is the same. I have 2 of these. Without the mounting flanges/legs the round part is identical top & bottom. The mounting flanges determine top & bottom as they are offset vertically from the fan opening.
Jeff

Took another look. I stand corrected. It is a 409 shroud. Agree on the width too. If it does not fit around the rad, the rad is NOT the right dimension.