Radiator shroud...

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nitronut

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I swapped out a slant six for a mildly built 360 in a '69 Valiant. I kept the stock/6 radiator and had a local radiator shop custom add two rows making it a 4 row radiator. (some folks tell me I should have went with 3 rows) Anyway, I just wanted to keep it looking stock. On a hot 95 degree day as long as I'm moving the car runs between 185-190 degrees. As soon as I'm stopped in traffic not moving for a couple minutes it jumps to 205-210 degrees but then shoots quickly back down to 185 when moving again. I do have an 8 inch electric fan w/manual switch for when it runs hot but doesn't make any temp difference when stopped and idling. Would like to add a wider radiator shroud than what's on there now. I've seen wider shrouds on stock 340 radiators and was wondering where to get one for my radiator. The photos show a 340 motor with the wider shroud and the other two photos show my /6 and 360 w/rebuilt radiator. The #'s on my radiator are: 2949072 and underneath those #'s are 38)086 The shroud mounts to my radiator with four bolts - two on each side. I can't find a stock-looking shroud anywhere. Any ideas or info would be greatly appreciated. Thanks!

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Plymouth14 1-23-07.jpg


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Can't help with your issue but that's a fine looking engine bay.
 
Is your water pump pulley not smaller than the crank pulley?
Thats one possible problem.
Pump/fan not spinning fast enough.
Theres a thread on the whole thing back a few months...
 
Is your water pump pulley not smaller than the crank pulley?
Thats one possible problem.
Pump/fan not spinning fast enough.
Theres a thread on the whole thing back a few months...
 
I'm moving the car runs between 185-190 degrees.

your thermostat is working great!

As soon as I'm stopped in traffic not moving for a couple minutes it jumps to 205-210 degrees but then shoots quickly back down to 185 when moving again.

That sounds normal to me. If you idle for longer does the temp continue to rise of does it level out in the low 200s?
 
By the way... if the first photo is your car, do you have a part number for your upper radiator hose. I like the way it looks.
 
your thermostat is working great!



That sounds normal to me. If you idle for longer does the temp continue to rise of does it level out in the low 200s?
If I'm idling in traffic temp rises to as high as 220 degrees...then I'll put in in neutral and increase the rpm which cools it down some.
 
No, that's the 340 motor. My cars photos are the second and 3rd shots...
 
no . new. u may have to replace the front rad support 4 more air flow . 26 nch 3 core should handle all even with a/c. even big block . the air opening for a 6 cyl s hurting for a v 8 u . either cut the support and add a v8 rad or totally cut front rad. support out and get a amd v8 rad support. may be ad fans temp controlled from block. at front of engine.
 
the 22 and 26 mopar rads r cheep. BIG just get air in and u will get performance. MOPAR X hemi owner..
 
the 22 and 26 mopar rads r cheep. BIG just get air in and u will get performance. MOPAR X hemi owner..
Thanks for that info...I sometimes wondered myself if the 22 inch radiator was wide enough...
 
Your fan is the culprit
It's not big enough and is shaped wrong. I see what looks like over 2 inches clearance. Air takes the path of least resistance. At low speed in traffic, the air is just going around the fan tips back to the front side, instead of fresh air being pulled thru that fat-boy rad.
The fan should fill up the shroud to within about a half inch at the minimum, and the hi-attack tips should be at least half way into the shroud. A thermostatic clutch will automatically control the maximum coolant temp, and disconnect the fan at speed,to freewheel, and save you power on the hiway. I highly recommend an all-steel 7-blade fan.
If your fan hits the shroud when under power, you will need to mechanically restrict it, which you probably have already done;or should have done.
 
so the only time temp is an issue is when your stopped in traffic for a few minutes?
sounds like not enough fan speed/air movement at idle.
looks like the electric fan is in front of the rad?
since it doesnt help I'd remove it...could be blocking some of the air flow thru the rad.

check this thread...good info within

Pulley Diameters
 
Your fan is the culprit
It's not big enough and is shaped wrong. I see what looks like over 2 inches clearance. Air takes the path of least resistance. At low speed in traffic, the air is just going around the fan tips back to the front side, instead of fresh air being pulled thru that fat-boy rad.
The fan should fill up the shroud to within about a half inch at the minimum, and the hi-attack tips should be at least half way into the shroud. A thermostatic clutch will automatically control the maximum coolant temp, and disconnect the fan at speed,to freewheel, and save you power on the hiway. I highly recommend an all-steel 7-blade fan.
If your fan hits the shroud when under power, you will need to mechanically restrict it, which you probably have already done;or should have done.
Good info - Thanks!
 
so the only time temp is an issue is when your stopped in traffic for a few minutes?
sounds like not enough fan speed/air movement at idle.
looks like the electric fan is in front of the rad?
since it doesnt help I'd remove it...could be blocking some of the air flow thru the rad.

check this thread...good info within

Pulley Diameters
Thank You!
 
I noticed the stock water pump you are using with the lower outlet on the drivers side. Not sure but I think this is the same cast iron unit used on 273's/318's that doesn't flow as well as later aluminum pumps. I went with the Mopar 8-blade heavy-duty aluminum water pump, 22" 3-core aluminum rad, stock fan shroud and 180 degree thermostat. Absolutely no issues, even in stop and go cruising with 500hp Magnum with early LA front timing cover and belt driven accessories, 4-speed and 3:91's.
 
If you want a stock shroud, I have one. Came out of my 73 Sport 340 with AC and the 26" radiator. Not sure how much it would cost to ship, but you can have it for $50.00 plus shipping if interested.
 
It seems to me that the rad is not the problem. Just airflow through the rad at ldle. I agree that it needs to be spaced forward into the shroud a bit more. Definitely check your pulley diameters too. That's the cheap easy most stock looking fix. If those things interest you!

Cley
 
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