[1969GPSJ]

It seems that the only readily available replacement heater cores are now aluminum. Does anyone have any experience with using these replacement heater cores, and how well have the held up in comparison to the classic Copper/Brass types used on the 50's, 60's, 70's, and 80's cars? Thanks in advance.

[Joe-Touring]

I’ve had one in my car for about 5 years, blows hot, no leaks. Does need attention regarding fitment, I imagine any core you install would need help in that regard.

I used adhesive backed foam tape to seal up the sides of the core to the box. The better the seal, the better the heater will work. I would also recommend removing all the old foam from the mix door and put some foam tape on that as well. If you can get the door to seal well, that will keep your car cooler when you have the HVAC set to cool.

I believe I bought my core from NAPA.

[nUcLeArEnVoY]

I replaced the heater core recently in my '79 Trans Am. They do reproduce copper/brass units for my car, thankfully, so I splurged and got that off of Ames. They're made by TSM and it fit perfectly. I vacuum-tested mine prior to install, and so far, no leaks and blows as hot as my 160-degree stat and upgraded cooling system will allow.

A lot of the time, installer error is a reason these new heater cores fail, and by installer error, I mean forgetting to restrict flow to it. During sudden high throttle situations, the hammer of water that rushes to the heater core could end up leading to early failure in an unrestricted inlet line to the core. That's why a lot of early Pontiac motors where the heater inlet came off the intake had an issue with failed heater cores. They eventually started implementing a bi-metallic coil into the heater hose nipple fitting at the rear passenger cylinder head, though the jury is out on the exact purpose of this coil - some say it is to restrict flow until the coolant temp reaches a certain point, others say it was to help with engine warm-up. In later Pontiac motors, the nipple instead just had a rubber restrictor inside them, restricting flow to 0.250. This restriction effectively dampens the slug of water to the heater core in high throttle situations, lengthening the service life of the unit. Police service units from the factory had the extra restriction in place since they're often operated with sudden high throttle.

When I replaced my heater core, I also replaced the rear passenger head nipple, since my engine still had the original nipple on it, and the rubber restrictor was missing. Probably dissolved after someone did a cooling system flush with strong chemicals in the past, and so my heater core was getting unrestricted flow which is what probably contributed to its failure. It was still the original Harrison heater core. To be extra safe, I also got a 1" aluminum spacer from McMaster Carr with a 0.250 hole and stuck it in-line in the inlet heater hose to act as an extra restriction like how the police units came.

The main issue I hear about with the aluminum cores is fitment inside the heater box and trying to slip the tubes through the firewall. All heater cores are rigorously tested for leaks before being sent out, so if you follow your due diligence and also make sure that you have restrictions to the heater core in place as from the factory, I'm sure it will last you many years of service.

[1969GPSJ]

I'm in the process of a complete frame-off for my '69 GP 428 4 speed SJ - consolidating 2 cars into 1, so I have a variety of components from each. 2 heater cores, 2 A/C boxes, 2 inside HVAC systems, etc. (but only 1 set of the rarest parts) I am just trying to make sure that once I get it all back together, I won't have a heater core leak soon after, requiring a tear down. My plan includes eliminating the factory nipple on the head and fabricating a balance tube system between the heads to feed the heater core, so I will make sure that the feed to the heater core includes an appropriate restriction. I have never heard of it being an issue, but slowing the coolant down in the heater core most likely cannot severely reduce the heating for the passenger compartment.

[nUcLeArEnVoY]

Originally Posted by 1969GPSJ

I'm in the process of a complete frame-off for my '69 GP 428 4 speed SJ - consolidating 2 cars into 1, so I have a variety of components from each. 2 heater cores, 2 A/C boxes, 2 inside HVAC systems, etc. (but only 1 set of the rarest parts) I am just trying to make sure that once I get it all back together, I won't have a heater core leak soon after, requiring a tear down. My plan includes eliminating the factory nipple on the head and fabricating a balance tube system between the heads to feed the heater core, so I will make sure that the feed to the heater core includes an appropriate restriction. I have never heard of it being an issue, but slowing the coolant down in the heater core most likely cannot severely reduce the heating for the passenger compartment.

It won't affect the heating of your passenger cabin at all. Mine only blows marginally hot because I have a 160 degree stat and an upgraded cooling system that, for the most part, maintains that temperature. I live in SoFLo, anyway, so I don't really use the heater that often - but I also didn't want to take the cheapo way out and block off the heater core, which is why I did it right and actually replaced it.

[78w72]

I have the alum heater cores in 2 cars, one for 7+ years & one for 15... both fit & function great, no tweaks or problems with fitment or install.

I use the original factory fitting in the head on one, & used a stainless washer/spacer with a .25 hole on the input line in the other with E-heads that cant use the factory outlet in the head.

[OCMDGTO]

I've been using one for a few years, so far so good.