My 71 Duster work in progress

The new engine definitely has an overheating problem - it pegged the mechanical gauge Saturday.

I've validated the gauge with a hand-held IR thermometer so I know it really did get that hot. I got distracted Sunday before I checked that the new thermostat is opening.

The car had an overheating problem with the 400 in it too, so I'm giving the radiator some side eye since it's the one part that was there for both engines.

I disassembled the distributor and lubed the weights and pivots but that didn't help because the engine was still liable to gain idle RPM over time.

The engine runs good, sounds good, might need new rockers. I can hear a ticking and those 273 rockers might be worn out.
 
Join the club, always something, at least mine runs cool, temp comes up about a quarter on the gauge & hangs there, did that driving around & even just sitting idling on some decent hot days.
I did have it recored.
Mines at the shop now getting the heavy oil & risoline, see if I get lucky?

Good luck with yours.
 
Last night I confirmed the thermostat opens at ~160, and checked the cap (I have a toolkit) then realized I didn't need to do that because I know it holds pressure. It says 16 on it, but it held to 20 off the car and on the pump.

I hunted down my RA receipts, found I had brain farted and bought a parts store level water pump. Maybe I should've spent more? Like 3x more?

www.summitracing.com

FlowKooler 1700 FlowKooler Hi-Flow Mechanical Water Pumps | Summit Racing

Free Shipping - FlowKooler Hi-Flow Mechanical Water Pumps with qualifying orders of $109. Shop Water Pumps, Mechanical at Summit Racing.
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The radiator is a 3-row 22" parts store replacement, with a trans cooler. It's clean, and the coolant has been drained and always comes out clean. The tubes look skinny, but still it's only a 360 so it should be able to cool it. They do make them with 4 rows

I think the modern concept is that larger tubes cool better.

www.summitracing.com

Cold Case Radiators MOP755K Cold Case Performance Aluminum Radiator Modules | Summit Racing

Free Shipping - Cold Case Performance Aluminum Radiator Modules with qualifying orders of $109. Shop Radiators at Summit Racing.
www.summitracing.com www.summitracing.com

I do dislike shiny radiators though


Now I'm onto something :D

If that doesn't cool it nothing will.
 
Ouchy, I wonder what that would have cost 10 years ago?
My recore was just a tad over that, 475, but I was lucky with A/C the 'Cuda's had 26 inch rads.
Can you loan me some of your oil pressure.
Picking mine up in a while, see what the mechanic says, & then drive it around the hood for a few days & see if I got lucky.
Still trying to decide if I try that pump on jackstands or just bite the bullet & pay the big bucks to have it done, be easier decision if I knew for sure the engine did not have to be lifted?
 
I looked for a second at brass radiators. Way too expensive.

I don't even know that the radiator is bad in mine. I'm just sick and tired of chasing problems where I end up spending more than I would have if I would've just ponied up the money to begin with.

I also learned that not all 7-blade fans are equal. Mine is a 2863200, which is for a 68 /6 with A/C. It only has 1/2" pitch, while the 68 383 and 440 has 2-1/2" pitch. I take that to mean more pitch moves more air so I might end up replacing that too. I've read that a repop GM 772 fan will work with an a-body cooling system. Those are 2-1/4" pitch. Didn't do it this time because that would be another $300 all said and told.

Also read that a /6 fan shroud turned upside down will work on an A-body with LA. I need more details on that though. I've got an OER shroud that is absolute junk, it's shaped like a banana.
 
I ordered a shroud & it was quite a bit thinner than the orig, I ended up cleaning up the original & used that! Don't remember the price but it went in the dumpster!
 
The OER part was $200, came out of the box cracked and looking like someone had already had a hotglue gun trying to fix it. I figure they would all be junk and cracked that way so I patched in a bit of sheetmetal and JB Weld to fix that. Then I let it sit on top of a pile of parts while I had the engine out and when I put it on it was warped like a banana. The big white zip tie is holding it back against the radiator.

1745348921892.png
 
Looks like one of my A/C duct ties!
I used to buy by the case, I have 5or 6 left for emergencies!
Running out of duct tape too, another case load item, it hurts paying like 10 a roll at the hardware store for crappy tape.
 
That's actually two zip ties hooked together. Each is only about 2 foot long.

Last night I pulled all the parts I'm replacing. All but the radiator will be here today but I have to work late so it will be at least Thursday before I get time to start replacing them.

I bet after all this it turns out the fan is the problem.

PS Dang it feels good to be able to do things again.
 
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The parts came in and the thermostat and water pump are installed.

The direct-fit radiator isn't really. With both bottom slots on the bolt, it's too high and crooked. There is a square hole punched right above both slots and I thought I'd have to cut through that to make the slot deeper, but it turned out to be a lot easier. When I put the driver's side bolt in the slot and the passenger side in the square hole, it all lines up perfectly. It's almost like it was made to install that way. So it's weird but it works.

I'm out to get a lower rad hose today and some screws for the shroud (if it lines up else I'll zip tie it.)

The lower rad hose is a pain because for hoses, A and E body use the same part number, so the're too long for an A-body and need to be cut-to-fit.
 
It's all together. I ran it until the thermostat opened, noted the temps dropped about 10 and held there until I noticed the thermostat was leaking so I shut it off. I was taking my chances with a slightly used gasket because the Mr. *GASKET* thermostat I bought didn't come with a *GASKET*. It didn't work out this time. I'm debating whether to cut one myself or to go to the parts store and buying a couple..

I started with this
1745698145225.jpeg

The parts store rad had 3 rows of these itty-bitty tubes with the core narrower than the tanks
1745698212212.jpeg

The Cold Case has 2 rows of these with the core as wide as the tanks.
1745698281967.jpeg

In process
1745698358934.jpeg

It's all assembled again.
1745698108398.jpeg


I noticed that when I checked the thermostat the other day, you could see flow in the radiator but it was pretty calm.

Now there is turbulence once the thermostat opens. Not sure if it's the water pump alone or a combination of that and the radiator but it's a huge difference. That definitely can't hurt anything.

I can't tell if it helped with overheating or not without a test drive though. It will never overheat in the garage, or if it does, I will blame it on no airflow and call it inconclusive.

Also, note the big gap where the shroud should meet the radiator. It's designed that way and I'm not sure trying to fill that gap would improve it.
 
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I had forgotten there are two different sizes of thermostat, and the smaller one will fall right down into the intake if the gasket didn't hold it. From my first look, the NAPA gaskets I bought yesterday won't do it. So I'm going to switch back to the one that was in it before this teardown. It is a Milodon high flow number MIL16406 from Mancini that I originally had in the 400.
 
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Update - this thing is driving me nuts.

Tried a gasket w/ Edelbrock Gasgacinch. Leak.

Tried a gasket with Right Stuff. Leak.

Tried a new neck and gasket with Indian Head. Waiting until tomorrow to refill the radiator.

If that doesn't seal, I've got Permatex® Water Pump & Thermostat RTV Silicone Gasket Maker to try without a gasket next.

I'm pretty sure I used Indian Head on it when I first assembled it. It didn't leak, and it sat for a long time before I added coolant.

I'm finding the leaks using a radiator pressure tester. The first try with Gasgacinch leaked so slowly there was no pressure bleed off after about 10 minutes, just a tiny leak barely enough to get things wet.
 
I think the car has always been in this area.

The prior owner shot himself but I haven't noticed any haunting.

I ordered 3 of these things, one for each engine I'm likely to build before it's over.
www.ebay.com

Thermostat Housing Gasket - MOPAR V-8 ENGINES - Part # RG-53063 SILICONE | eBay

OEM #: 35063, 53063. THERMOSTAT HOUSING GASKET -. OLDER MOPAR V8 Engines. One silicone gasket. Gasket is1/8" thick silicone. grade AMS silicone and designed to withstand temperatures. Reusable gasket.
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I was amazed that there were no leaks when I first started the engine. It's catching up with me now.
 
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