Heater core hose restrictor
 

Is this pic correct …
Coolant flow from back of head to lower heater core pipe ….
Looking at installing a restriction in the hose to help reduce heater core failure and want to be sure of the correct hose for install…

There are head hose fittings that have a coiled restrictor built into the fitting. My heater core has a crimped inlet. I suppose that could act as a restrictor too.

Hi Ed
Yes that’s a restriction for sure that’s the inlet then the lower and that tube goes to the back of the head …right?
My new heater core isn’t crimped and the old is long gone…that’s why I was trying to figure which was the inlet

I have the same sorta dilemma and question in my mind. I have a replacement heater core that doesn't have a crimped inlet. This makes me wonder how much better my cooling system could have been if this wasn't bypassing so much coolant. Not really room to crimp it without getting into the hose retaining ridge. My solution is to install a valve. I'm converting to an LS engine. So my cooling needs should go down a lot. I'm installing one of these: https://www.summitracing.com/parts/fss-84706 I may choose to close the heater core off entirely during the summer.

I have an in-line restrictor somewhere I had made up long time ago from a post here on py….I need to find the restrictor if I can or have another made,,,,
I’m just trying to verify which coolant line it’s to go in…which by the looks is the lower hose off the core to the back of the head

Correct 5/8 line from the head to the core .

The crimp in the picture above doesn't look like much of a restriction based on area. Maybe turbulence.

JS ... put one of those valves on my tractor for the cab heater ... been working great for years.

My 68 has both crimped inlet to the core and restrictor in the head fitting.

That's good to know!

Thanks appreciate the affirmation

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Are you looking for the restricted fitting that goes in the head? What heads are you running?
Hose was 5/8" from back of head to lower heater core so it removed air from heater core. 3/4" line from heater core to return on water pump.

No I have a fitting that was made up that Goes into the line I found it last nite. .250” hole pretty sure it is
Runnning 6x heads…

Nipple pressed into stock head has a restictor in as well.

The later heads with the hose nipple with the baffle inside do help with the slug of water that comes out of the head and goes to the inlet tube on the heater core.

But a better solution on all Pontiac engines (with heater cores is to make a restrictor that has a 1/4" hole drilled thru a 1" long section of material: Wood, solid plastic rod, metal, etc.

Years later the Police package heater core circuits always had the plastic .250" Diameter
1" long inserts in the inlet line to the heater cores.

I posted about this many, many years ago. Bending the inlet tube inward helps but still has too much inlet area and a slug of water can still kill the heater core over time.

Tom V.

Tom where should I place this restrictor as far as position in the hose ????..Inch or two from the core ???? OR the cylinder head end???

Interesting topic. I'm installing Vintage Air (VA) in my 69 bird and asked VA if a restrictor is needed for the heater core, which is inside the under dash evaporator assembly. The tech said the heater cores are tested at very high pressure and no restrictor needed. Is it for PSI or overall flow?

I made a restrictor with two 3/8" x 1/8" brass pipe bushings & a 1/8" brass pipe nipple. The ID of the pipe nipple is 5/16. Thats half the ID diameter of the heater hose. The bushings fit nicely in the heater hose. You just need a couple of hose clamps to secure them. I did this about ten years ago and the heater core has not failed. As far as heater output is concerned it is not affected. It still puts out plenty of heat when needed. The above-mentioned parts are available from any hardware store or home improvement store. My car is strictly a driver not a show car, so originality is not my concern. Hope this helps.Attachment 592196

Does anyone know if the heater control valve in a Vintage Air system will function as a restrictor?https://www.vintageair.com/instructi...New%20Kits.pdf

I think the Vintage Air core is of the new later design and not the old soldered brass/copper. May not have a problem to correct. (I hope)

What makes the newer style heater cores less likely to leak?

When I asked VA tech support about the need for a restrictor the tech said not needed cause they test the heater cores at very high pressure. Of course the heater core is inside the evaporator assembly and I hate to take chances as it’ll be no fun fixing a leak should one ever develop.