• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

26" Shroud and aluminium Rad - gap


Active Member
Local time
12:53 AM
Jul 26, 2022
Reaction score
Hi guys,

My 66 Belvedere has a 26" inch Champion Radiator. It works fine, but in summer time the Temperature rises a lot during idle in traffic.
I added an electric fan in front of the Rad, which helps.
If I start moving again Temperature drops really fast to normal.

I think the Problem ist the gap in the shroud between the radiator and the shroud itself.
A lot of air is not going through the radiator.
I tried to put some foam in there, but under high rpm it was sucked in trough the Fan.

So I am thinking about buying a cooper oem style radiator from us Radiator.
Does anyone have a picture how the shroud fits there?
Is there still a gap ?

Kühler, B-Body, 26″, 66-69, BBM, High Efficiency, A/T

Price is not cheap, but I dont care of it solves the Problem..

Best wishes from Germany.

How hot is it getting? Factory gauge?
Yes, you have an air flow problem at idle. My shroud to radiator gap is maybe 3-4mm
My 1966

Radiator came from Ebay seller 1966-1972 Mopar B & E Body Aluminum 26" Radiator Road Runner Challenger Cuda | eBay

OEM style shroud came from - 1970-73 Mopar B and E Body Radiator Fan Shroud - 26 Inches - Reproduction | eBay

On my other 1966, It has the OEM stock copper radiator and correct shroud. And it fits about the same as this aluminum one does as far as gaps goes.

Both of mine run right on the 180 thermostat , until ambient temps get in the 100s around here. Then both will climb a little bit. ( thats typical ) to about 200 degrees. But both cool right back down as soon as Im moving again


Last edited:
Try some foam weatherstrip attached to the shroud (for easier removal if needed) to seal the gap. Most heavy equipment I worked on had closed cell foam between shroud, radiator, after cooler, hydraulic cooler. Also fan blade should be half in, half out of shroud.
That gap is very minimal. I have aluminum radiator and 26" factory shroud. 19" 11 blade direct drive mechanic fan. At idle in the summer, it climbs as high as 220° in 125° ambient temps. That's idling for 10 minutes w a/c on. Still shows in normal range on factory gauge. I have metal duct tape sealing every gap, top and bottom. If it is not burping fluid at idle, going out of normal zone at idle, it's just fine.
Since this was not mentioned yet and the radiator you have is newer, I would double check to make sure you don't have a build up of casting sand or other crud in your radiator or other parts of the system. This problem was apparently worse with big block Mopars, than the small blocks. It should be apparent when you drain or flush to coolant if there are many fine particles or the coolant is rust colored.

Also, depending on if the car has a/c or not make sure you have the correct water pump pulley. The diameters were supposedly different for a/c and non-a/c applications and coolant flow cannot be too fast or too flow or you will have problems keeping cool at idle. Hope this helps!
The better its sealed the better the cooling..... between the radiator shroud & radiator support.
Remember on any radiator and shroud setup the fan has to be half in and half out of the shroud for proper air flow.