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P7/P8 Plymouth Radiator Interchange Info Needed #434900
08/11/09 04:02 PM
08/11/09 04:02 PM
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Posts: 1,392
Thayer, MO
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bohmer2 Offline OP
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bohmer2  Offline OP
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Thayer, MO
I am trying to track down a stock radiator to use the tanks for a core for my 1939 plymouth. I am hoping to avoid paying $700 for an aftermarket aluminum custom job. I have read that with a mild street small block a stock radiator might even be capable of cooling the motor. Personally, I would like to just take a set of stock tanks to a local radiator shop and have one put together.

So will any of the 36-41? radiators interchange?

Re: P7/P8 Plymouth Radiator Interchange Info Needed [Re: bohmer2] #434901
08/11/09 08:12 PM
08/11/09 08:12 PM
Joined: Sep 2003
Posts: 19,237
north of coder
moparx Offline
"Butt Crack Bob"
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north of coder
my hollander states that every year [36-41] takes a different number. having said that, my gut feeling is the integral mounting points are the key to the interchange, meaning the differences in the slight differences in design between years. i would think the tanks would be very close if not identicle. the hollander does not list tanks.

Re: P7/P8 Plymouth Radiator Interchange Info Needed [Re: moparx] #434902
08/11/09 08:35 PM
08/11/09 08:35 PM
Joined: Sep 2005
Posts: 12,481
Chino Valley
RodStRace Offline
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Chino Valley
I would have to agree, however, I have a stock 40 (P-10) and can take pictures and measurements if that will help. Maybe there will be enough of us to get the answer

Re: P7/P8 Plymouth Radiator Interchange Info Needed [Re: RodStRace] #434903
08/11/09 10:47 PM
08/11/09 10:47 PM
Joined: Jan 2003
Posts: 10,483
Freeport IL USA
poorboy Offline
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Freeport IL USA
Better ask your local guy how much he's going to charge you to recore a rad. Several years ago, recoreing a rad was almost $200 here and I'm sure it hasn't gotten any cheaper.

As far as rad tanks are concerned, newer (46-48) have an extra piece on the cap area so it can be pressureized, before that they were not pressureized, so you would have to modify the cap area to run a modern pressurized system, might even still have to modify the 46-48 tanks. Something to think about.

The lower hose connection is at a strange angle, (upper hose is too I believe) because the rad was built for an inline 6 or inline 8, the hoses wrap around towards the engine. They have to be cut and modifyed to clear a v8. We messed around with a few original rads on my son's 47 to try to work on the 360 in it, never was sucessfull. It was easier to modify the front sheetmetal to clear a modern rad. Ones from mid 70s 318 trucks are reasonably small and will cool a mild small block. They are cheap to buy new @ just over $100 last fall, I think I only paid $200 for the big 3 core HD truck rad at NAPA last year for my 4x4, and it was USA made. I'd modify the sheet metal a bit before I'd drop $700 on any radiator.

I used the rad from a v6 Dakota in my 39 and only had to drill new holes to bolt it and spread the two side sheetmetal pieces to match the rad core (thinking about 2" per side.) Gene

Re: P7/P8 Plymouth Radiator Interchange Info Needed [Re: poorboy] #434904
08/12/09 08:20 PM
08/12/09 08:20 PM
Joined: Sep 2003
Posts: 19,237
north of coder
moparx Offline
"Butt Crack Bob"
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Joined: Sep 2003
Posts: 19,237
north of coder
thanks for jogging my memory gene ! i had forgotten about those goofy angles. and wasn't some of those years a cast something [iron?] neck ?

Re: P7/P8 Plymouth Radiator Interchange Info Needed [Re: moparx] #434905
08/12/09 11:32 PM
08/12/09 11:32 PM
Joined: Jan 2003
Posts: 10,483
Freeport IL USA
poorboy Offline
I Live Here
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Posts: 10,483
Freeport IL USA
The ones we cut were thin wall tube, much like exhaust tubing, if I remember correctly. I do remember that we couldn't just cut it off and stick a hose on it because it was too low, we had to make a couple cuts and make a sort of "z" shaped neck to clear things on the bottom hose connection. At the top I think we were able to cut it and put a hose on it. Also seemed to remember the hose necks were were a large diameter, near 2", I think. It was a few years ago. Gene

Re: P7/P8 Plymouth Radiator Interchange Info Needed [Re: bohmer2] #434906
08/13/09 09:00 AM
08/13/09 09:00 AM
Joined: Jan 2003
Posts: 1,331
Oregon
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earlymopar Offline
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Posts: 1,331
Oregon
The direction you're heading is certainly one way to get a good fitting radiator that will fit within the stock dimensions while avoiding the ridiculous prices of the big name aftermarket radiators.

I was in the same boat with regard to cost but also didn't have my stock 37' radiator to re-core.

I simply bought a $170 aftermarket aluminum radiator from an AFCO distributor on Ebay. I went with the largest size that I knew would fit with my stock grill shell support. Given that these are typically crossflow radiators, I cut-off and capped-off the existing neck and mounted the radiator sideways in my grill shell support. This placed the hose inlet and outlets in the correct position as with a vertical flow radiator. Then I simply added a fill neck in the upper radiator hose between the radiator and the thermostat housing and, a petcock-drain in the lower hose. This set up cools very well on a 400 hp small block.

- EM

Last edited by earlymopar; 08/13/09 09:02 AM.






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