Cooling Issue - 1964 Dart GT - 273 with automatic and A/C

[Dart5150]

Hello all. Apologies for the length of the post, but I wanted to be thorough. I'm having a cooling issue that I can't seem to chase down, was hoping for some insight from those farther along the Mopar journey than I am. Pictures are below.

We have a '64 Dart with a 273 and push-button automatic. Also has AC and power steering. I'm not sure if the AC is factory/original, but the compressor is Mopar and there is a Mopar branded evaporator/blower mounted under the dash. The AC is currently disabled, as I had to repair some leaks and I need to charge it (but wanted to address the cooling issues first). The radiator is an aftermarket aluminum radiator, and has two 1-inch rows, which I've heard is enough for a small block V-8. It has a 7-blade fan that is about 17" in diameter, with about a 1-inch overhang on the passenger side of the radiator. No shroud, which I've heard is normal for early A-Bodies. The radiator core is roughly 16" high by 18" wide, and the mounting point on the radiator support panel are about 21.25" on center.

Anyway, the car runs at ideal temp when cruising, right up the middle of the gauge, but approaches the hot side of the temp gauge on a 90+ degree day and/or in stop and go traffic. Quickly enough that I either find a way to get moving again or pull over for a cool down. So starting with the simple stuff first, I pulled the thermostat and found that it had failed open, which I had suspected. I replaced it, but this didn't resolve the issue. Next, thinking the radiator may be too small (and wanting something more stock in appearance anyway), I ordered the radiator from Classic Industries that's supposed to fit the '64 Dart with a V-8. It was too big, and didn't align with any of the factory mounting holes. Next I installed an electric fan with a relay, and this didn't help. Part of the problem with the electric fan is that I only had 3.2" of clearance between the radiator surface and the fan pulley. So that limited my airflow options, although the one I bought was a slim fan rated for over 1900 cfm. Then I pulled the fan and reinstalled the mechanical fan because the electric fan didn't help and it sounds like a 747 on final approach .

So I have some questions.

1 - Is it possible that somebody swapped a V-8 into a Slant-6 car, and there is a different radiator support panel for the V-8 car? I ask because a larger radiator will have to draw air through the same sized opening in that panel anyway.

2 - Is there a different water pump/pulley for a V-8 car with AC?

3 - Are there any known cooling issues with these engines? For example, I know that it's easy to incorrectly orient or 'flip' the head gaskets on a Ford 289 if you don't pay close attention, which results in overheating issues.

Thanks in advance for any insight you may be able to provide.

 

[Syleng1]

As a guy who has a highly modified 273 commando engine in my 66 barracuda with auto and ac. Mine has a factor radiator and fan shroud and clutch style fan. No issues getting hot. I tried the aluminum radiator route and honestly it had a tough time like yours does. I’m not saying the aluminum is the issue.
The temp fluctuates a lot with aluminum.
Also, with gauges that are 60years old verify they are operating properly. May be a aftermarket gauge installed will show your factory gauge is out of calibration. As for the engine, normal stuff to check is:
Water pump (cast iron unit)
Thermostat
Hoses
Blockage in the coolant system - drain and flush the block.
Ignition timing
Running too lean.
Slipping converter / transmission.
Just a few.

Syleng1

 

[Dart5150]

As a guy who has a highly modified 273 commando engine in my 66 barracuda with auto and ac. Mine has a factor radiator and fan shroud and clutch style fan. No issues getting hot. I tried the aluminum radiator route and honestly it had a tough time like yours does. I’m not saying the aluminum is the issue.
The temp fluctuates a lot with aluminum.
Also, with gauges that are 60years old verify they are operating properly. May be a aftermarket gauge installed will show your factory gauge is out of calibration. As for the engine, normal stuff to check is:
Water pump (cast iron unit)
Thermostat
Hoses
Blockage in the coolant system - drain and flush the block.
Ignition timing
Running too lean.
Slipping converter / transmission.
Just a few.

Syleng1View attachment 1716291558

Very nice engine bay you have there! Thanks for your input. The gauge operation tends to correctly follow conditions, using an IR thermometer. But validation with an aftermarket gauge may be a good idea. Can you recommend one? Also, where did you find your stock radiator, or is it original? Are the mounting points the same dimension described above? About 21.25" on center? Water pump is building pressure and you can see flow in the radiator, so I made the assumption that that wasn't an issue. I'll revisit timing and carb lean/rich settings. Can you elaborate on the slipping converter/trans?

 

[mrs49]

Hello all. Apologies for the length of the post, but I wanted to be thorough. I'm having a cooling issue that I can't seem to chase down, was hoping for some insight from those farther along the Mopar journey than I am. Pictures are below.

We have a '64 Dart with a 273 and push-button automatic. Also has AC and power steering. I'm not sure if the AC is factory/original, but the compressor is Mopar and there is a Mopar branded evaporator/blower mounted under the dash. The AC is currently disabled, as I had to repair some leaks and I need to charge it (but wanted to address the cooling issues first). The radiator is an aftermarket aluminum radiator, and has two 1-inch rows, which I've heard is enough for a small block V-8. It has a 7-blade fan that is about 17" in diameter, with about a 1-inch overhang on the passenger side of the radiator. No shroud, which I've heard is normal for early A-Bodies. The radiator core is roughly 16" high by 18" wide, and the mounting point on the radiator support panel are about 21.25" on center.

Anyway, the car runs at ideal temp when cruising, right up the middle of the gauge, but approaches the hot side of the temp gauge on a 90+ degree day and/or in stop and go traffic. Quickly enough that I either find a way to get moving again or pull over for a cool down. So starting with the simple stuff first, I pulled the thermostat and found that it had failed open, which I had suspected. I replaced it, but this didn't resolve the issue. Next, thinking the radiator may be too small (and wanting something more stock in appearance anyway), I ordered the radiator from Classic Industries that's supposed to fit the '64 Dart with a V-8. It was too big, and didn't align with any of the factory mounting holes. Next I installed an electric fan with a relay, and this didn't help. Part of the problem with the electric fan is that I only had 3.2" of clearance between the radiator surface and the fan pulley. So that limited my airflow options, although the one I bought was a slim fan rated for over 1900 cfm. Then I pulled the fan and reinstalled the mechanical fan because the electric fan didn't help and it sounds like a 747 on final approach .

So I have some questions.

1 - Is it possible that somebody swapped a V-8 into a Slant-6 car, and there is a different radiator support panel for the V-8 car? I ask because a larger radiator will have to draw air through the same sized opening in that panel anyway.

2 - Is there a different water pump/pulley for a V-8 car with AC?

3 - Are there any known cooling issues with these engines? For example, I know that it's easy to incorrectly orient or 'flip' the head gaskets on a Ford 289 if you don't pay close attention, which results in overheating issues.

Thanks in advance for any insight you may be able to provide.

View attachment 1716291547

View attachment 1716291548

View attachment 1716291549

 

[mrs49]

Look on drivers side A pillar, if the tag there starts L4 you have a /6 body, if you have L6 it's a V8 body. The radiator support is different between the two bodies. The /6 car came with a 18"radiator,the V8 with a 22". If you can a V8 donner you can cut out the passenger side mounting panel for the radiator and graft it in to the /6 radiator support. Of course you will have to take the front of the car apart, and the engine out to have room to tack and wield things back. A lot of work but you will be able to install the 22" radiator. The V8 cars did come with shrouds (very hard to find) with 4 small brackets, bolts( 1/4X1/2) and square nuts that mounted to the radiator, that the 2 piece shroud then mounted to. Hopes this helps and gives you a insight into what you face, may be easier to go back to a /6 or do some creative fabrication.

 

[65 Dartman]

I’ve read somewhere (perhaps on this forum) that the 273 2 barrel in 64 got a smaller radiator than the 22 in ones in 65 and later.. by your dimensions of the aluminum radiator, it sounds like it was comparable with the smaller 64 V8 radiator. Does either radiator cover part of the core support? That might be an issue. I see no shroud which would certainly help.

FWIW your AC appears to be likely Aftermarket installed using a Chrysler compresser. If it were dealer installed they would have mounted the horizontal drier on the top of the passenger inner fender

 

[RustyRatRod]

That's the correct width radiator for an early V8 car. I recommend a high flow 160 thermostat. May or may not help, but it sure won't hurt. Also, measure your crank pulley and water pump pulley diameter. Your water pump pulley should be smaller than the crank pulley so that it is overdriven. If it's not, that could certainly cause some of your low speed heating issues.

 

[slantsixdan]

The /6 car came with a 18"radiator,the V8 with a 22".

…starting in '65. In '64, only the 19"-wide radiators were factory-installed, whether the car had a 6- or 8-cylinder engine.

 

[Dart5150]

Look on drivers side A pillar, if the tag there starts L4 you have a /6 body, if you have L6 it's a V8 body. The radiator support is different between the two bodies. The /6 car came with a 18"radiator,the V8 with a 22". If you can a V8 donner you can cut out the passenger side mounting panel for the radiator and graft it in to the /6 radiator support. Of course you will have to take the front of the car apart, and the engine out to have room to tack and wield things back. A lot of work but you will be able to install the 22" radiator. The V8 cars did come with shrouds (very hard to find) with 4 small brackets, bolts( 1/4X1/2) and square nuts that mounted to the radiator, that the 2 piece shroud then mounted to. Hopes this helps and gives you a insight into what you face, may be easier to go back to a /6 or do some creative fabrication.

Very helpful, thanks. I'll check it out. May be easier to try my luck with fabbing a shroud.

 

[Dart5150]

I’ve read somewhere (perhaps on this forum) that the 273 2 barrel in 64 got a smaller radiator than the 22 in ones in 65 and later.. by your dimensions of the aluminum radiator, it sounds like it was comparable with the smaller 64 V8 radiator. Does either radiator cover part of the core support? That might be an issue. I see no shroud which would certainly help.

FWIW your AC appears to be likely Aftermarket installed using a Chrysler compresser. If it were dealer installed they would have mounted the horizontal drier on the top of the passenger inner fender

Good to know, thanks!

 

[Dart5150]

That's the correct width radiator for an early V8 car. I recommend a high flow 160 thermostat. May or may not help, but it sure won't hurt. Also, measure your crank pulley and water pump pulley diameter. Your water pump pulley should be smaller than the crank pulley so that it is overdriven. If it's not, that could certainly cause some of your low speed heating issues.

Thanks for this info. I looked at the two pulleys, and they appear to be roughly the same size, about 6-5/8". Any recommendation on size, and a vendor? I looked at Classic Industries and they only have the 6-5/8 pulley. They have the 160 high flow stat, so I'll get one of those.

 

[RustyRatRod]

Thanks for this info. I looked at the two pulleys, and they appear to be roughly the same size, about 6-5/8". Any recommendation on size, and a vendor? I looked at Classic Industries and they only have the 6-5/8 pulley. They have the 160 high flow stat, so I'll get one of those.

Yeah that's 1:1. That could be some of the issue. I would put up a wanted ad in the classified section asking for a water pump pulley smaller than 6 5/8. Someone has something.

 

[D/Dart man]

Just a side fact about the 1964 Dart radiator: Since the V8 was a late addition to the '64 Dart they did not use a different radiator support panel than the /6. Therefore the radiator is noticeably off center with the fan blade on '64 273 V8's. The fan blade overhangs to one side.
But I doubt if this is part of the author's issue since my '64 V8 Dart doesn't get that hot even on 100 deg. days.

 

[Syleng1]

Very nice engine bay you have there! Thanks for your input. The gauge operation tends to correctly follow conditions, using an IR thermometer. But validation with an aftermarket gauge may be a good idea. Can you recommend one? Also, where did you find your stock radiator, or is it original? Are the mounting points the same dimension described above? About 21.25" on center? Water pump is building pressure and you can see flow in the radiator, so I made the assumption that that wasn't an issue. I'll revisit timing and carb lean/rich settings. Can you elaborate on the slipping converter/trans?

1) almost any well known gauge manufacturer will do. Since may or may not stay- less expensive with a sending unit is best.
2) that is the stock radiator in my car. I can get you a part number off the top tank - pm me for it. I had spent the money and had the radiator completely redone by a radiator shop near me in CT for about $650. This was after the aluminum radiator from cold case failed to do the job. I also did not like the look in my car all square and aluminum as my car was built to look like what you would find in 1968-69 of a modified 66 Barracuda.
3)trans / converter slippage- basically a slipping converter (getting worn out) generates extra heat, slipping trans or “sloppy” trans allows for more heat all dumping into the radiator. So even if it adds 10-15 degrees more…. It’s 195-200 instead of 180. I’m not sure how fresh your drivetrain is but if it is getting tired, that could be some trouble.

 

[Bewy]

Temp fluctuates a lot with alum [ post #2 ]????

My rad must be made of a 'special' alum because the temp only varies by a needle width for temps ranging from 8 to 45* C.

 

[mrs49]

…starting in '65. In '64, only the 19"-wide radiators were factory-installed, whether the car had a 6- or 8-cylinder engine.

 

[mrs49]

Not so.

 

[JDMopar]

A small part of the OP's troubles may come from where he lives. The Columbia, SC area gets stifling hot! When somebody in hell pisses the devil off, he sends them to Columbia for punishment! @Dart5150 research water pump pulley's for 64-69 cars with AC. I think the pulley's on them are smaller, to overdrive the pump like Rob said. Bouchillon Performance, down around Charleston sells reproduction pulleys, so maybe they will have what you need. You will need one for a 64-69 car because you have a cast iron water pump. The depth of the pulleys changed in 70 when they went to the longer nosed aluminum water pump. Your Dart sure looks nice, so I hope you can get it sorted out.

 

[cudamark]

'64 A-bodies all came with 19" wide radiators from the factory. The factory A/C car got a 3 row cored radiator, but, I don't believe they had a shroud that year on the V8. If they did, I've never seen one. I would use a rigid 6 or 7 blade fan blade....no flex fan. If your engine runs cool enough at speed, the flow is probably ok, and it's mostly an air flow issue at idle/stop. A mismatch on pump/pulley combo can have an effect too that can be masked at higher than idle RPM. As a rule, the non-A/C cars used an 8 impeller pump and a larger diameter water pump pulley. The A/C cars used a 6 impeller pump with a smaller diameter pulley. Seems backwards eh? It has to do with water flow. The non-A/C pump has more impellers, but, spins slower than it's A/C sister, which spins faster at a given RPM. A mismatch can have strange results sometimes....but not always. I've seen 8 impeller pumps have no problem on A/C cars, and others that had cavitation issues with the coolant foaming up to the point where it wouldn't cool properly. The opposite can be true using a 6 impeller pump on a non-A/C car where the flow is inadequate. It also has an effect on the fan speed if you have the wrong pulley combination. The '64 A-bodies with a V8 had one strike against them with that small radiator, which was improved to the 22" radiator the next year. Converting isn't all that easy, but, I've seen it done. If I were you, I'd probably go with a heavier duty radiator, 7 blade rigid fan, and fabricate a fan shroud for better air flow at low RPM. This is all assuming that the engine cylinders weren't bored too thin and is running with the proper air/fuel ratio.

 

[slantsixdan]

Classic Industries

Your luck with repairs and upgrades will get a lot better once you start disregarding the existence of that garbage company selling garbage parts at LOLWTF prices.

 

[slantsixdan]

The factory A/C car got a 3 row cored radiator

That is not the case. For one thing, there was nothing such as a factory A/C A-body in '64; that started in '65. The '64 A-body A/C was still a dealer-installed package, which did not include a new radiator. And even in '65, the factory A/C cars didn't get 3-row radiators.

I don't believe they had a shroud that year on the V8.

Fan shrouds were available for the '64 A-bodies with \6 and with V8 engines. They were typically installed on cars with A/C installed and/or trailer-tow equipment. '64 was the last year for the ring-style shroud; starting in '65 they were box-type shrouds. Both kinds were 2-piece items, upper/lower.

I would use a rigid 6 or 7 blade fan blade

Read this.

mostly an air flow issue at idle/stop.

Yup, low-speed/stopped-in-traffic heatup is usually a matter of insufficient effective airflow across the rad. Make sure there's an adequate fan, a shroud will help quite a lot, and install the hood-to-rad-support seal on the underside of the hood; that's another A/C and trailer-tow piece to prevent air going up over the radiator instead of through it. Gary Goers № W81, available (if anywhere) from Quirey Quality Design, the outfit who bought out Goers when his health failed.

The '64 A-bodies with a V8 had one strike against them with that small radiator

As built yep, they did. That strike could easily be erased even back in the day by having a 3-row core put into the stock rad (easy on the V8 cars; plenty of room between front of engine and back of rad). Decades later, high-efficiency rad cores with denser fins made it even less necessary to try to hack in a wider rad, and now we can do it even better still.

 

[trapster]

A thermostatically controlled pusher fan also wired into ac compressor is probably your best solution at this point. as for the difference in radiator between /6 and V8 for 1964, The only difference i know of is the side of the radiator the bottom hose connects on.

 

[cudamark]

That is not the case. For one thing, there was nothing such as a factory A/C A-body in '64; that started in '65. The '64 A-body A/C was still a dealer-installed package, which did not include a new radiator. And even in '65, the factory A/C cars didn't get 3-row radiators.



Fan shrouds were available for the '64 A-bodies with \6 and with V8 engines. They were typically installed on cars with A/C installed and/or trailer-tow equipment. '64 was the last year for the ring-style shroud; starting in '65 they were box-type shrouds. Both kinds were 2-piece items, upper/lower.

View attachment 1716292338



Read this.



Yup, low-speed/stopped-in-traffic heatup is usually a matter of insufficient effective airflow across the rad. Make sure there's an adequate fan, a shroud will help quite a lot, and install the hood-to-rad-support seal on the underside of the hood; that's another A/C and trailer-tow piece to prevent air going up over the radiator instead of through it. Gary Goers № W81, available (if anywhere) from Quirey Quality Design, the outfit who bought out Goers when his health failed.



As built yep, they did. That strike could easily be erased even back in the day by having a 3-row core put into the stock rad (easy on the V8 cars; plenty of room between front of engine and back of rad). Decades later, high-efficiency rad cores with denser fins made it even less necessary to try to hack in a wider rad, and now we can do it even better still.

The 2524306 and 2524313 are the '65-6 version shroud. As for '65 models not having a 3 row radiator, I've owned several that did. The radiator is 2524962 for the 3 row. 961 for the 2 row. You're correct on the '64's being dealer installed. I should have said the Mopar version of A/C instead of some of the aftermarket setups that were available back then. I still don't remember having seen a '64 model 273 with a shroud though. It makes sense that it would be part of the kit however. I have seen the 6cyl shroud though, so, they probably had one. It would be unique for that year.

 

[trapster]

1964 v8 radiator shroud, is both slightly ineffective and extremely rare.

 

[slantsixdan]

1964 v8 radiator shroud, is both slightly ineffective and extremely rare.

Given the choice, I'll take limited efficacy over no efficacy (no shroud).

As for rare: yep, pre-'67 A-body fan shrouds are all rare, and the earlier the build year the rarer they get. That said, I'm guessing fairly good odds there might be one at one or another of the Arizona old-car yards, or maybe hanging on the wall at Wildcat. If someone were to happen upon one, it would not be difficult to reproduce.