CJG

There is no vacuum running to this only the coolant hose. Can i replace it with some sort of 90 degree elbow to clean up the looks?



There is nothing that goes to this at all its just plugging a hole. Any reason i cant replace it with just a pipe plug?

joe_padavano

The first one is a heater control valve used only on cars with A/C. If you do not have A/C, replace it with the special hose nipple with the restrictor.



The second is the Thermal Vacuum Switch for the Transmission Controlled Spark system. Be very careful not to damage that unit when you remove it. It is not reproduced and is sought after by restorers.

CJG

Awesome thanks!

CJG

Ok, so we kind of broke the heater control valve while trying to install the trans dipstick tube. Oreillys has some nipples similar to the one above, however they are just wide open, no restriction. Is there a reason why there needs to be a restriction inside?

Indy_68_S

I'm purely guessing here, but on my '68 non A/C there is NO coolant/heater valve. It was this way from the factory for non A/C cars and has the 'restricted' nipple. Hot water is always circulating (albeit restricted) thru the heater core. I suspected the restriction was to keep the cabin livable on hot days!

CJG

I do not even have a heater core or any of the ductwork or any of that in the car. I guess what I'm asking is if I can replace the valve with a screw in nipple that is just a wide open nipple like Oreilly s has or do I have to find one with the tiny restrictive hole like the one pictures?

Indy_68_S

Did a little digging....

In A/C cars the control valve acts as the restrictor. Non A/C depend on the nipple restrictor.

Looks like the restriction has a purpose. The main issue seems to be sound/noise of the coolant rushing thru.

Example here...
https://classicoldsmobile.com/forums...tml#post361345
&
https://classicoldsmobile.com/forums...tml#post955933

I also found some chatter about slowing the flow to prevent over cooling of the back of the engine, but nothing definite.

I'd think you would be fine running it 'open'.

CJG

Awesome thanks!

MDchanic

If you don't have a heater core, just put a pipe-thread plug in it.

That'll "clean it up" better than anything.

- Eric

CJG

You mean an actual plug? Then if so can I just do away with the hose going from it to the water pump and cap off the nipple on the pump?

joe_padavano

That's what the factory did for heater delete cars.

CJG

Ok that makes it easy. If we ever decide to run heat we can always put it back. Thanks!

oddball

Joe, how are those restricted nipples installed? I'm not seeing an engagement surface for sockets or wrenches, maybe just a slotted top for a screwdriver? Seems a tall order for 3/4" NPT...

midrange

I used a drag link socket to install mine.

joe_padavano

An excellent solution. A section of appropriate thickness angle iron also works.

Fun71

The restriction also acts as a pressure reducer to prevent the heater core from ballooning and rupturing.