I previously posted about a fuel line, carb to pump, for a 77 Cutlass Salon 350R. Inline Tube solved by duping my original, after having shipped me one for a 1972/older. I didn't know the diff between the one for 1972 and the one for a 1977.

Onto the HCV, I removed the top h/h to achieve better access to the lower h/h, what you see in the pic is what came off in my hands, The part that screws into the intake is still there. On an older thread I saw a similar pic, Joe P said it was for a Buick. Anyway, the lower is supposed to be for a 1976/7 Cutlass 350, it has a threaded fitting that doesn't exist on the one that came out in my hands.

Wrinkle is the car is equipped with factory TempMaiic climate control.

Question is does the top look like original (possible it is not) and is the lower the correct one? Any other comments welcome as well.

Thanks and regards to all

 

by Joe P, and he says is good for a 1976, which begs the ? what do I thread into the smaller threaded hole?

 

That's a blind hole for a blower delay temp switch. Not every car had that option.

 

Nothing, leave it blank/empty.

 

The Tempmatic system should have a sensor that screws into that threaded hole. Apparently your earlier replacement valve didn't have that provision.

 

Thank you, Joe, don't suppose I could trouble you (or anyone) for the p/n or other identifying info? Since the mechanic who replaced the original pitched the sensor and my wiring diagram does not show p/n's.

 

it has tapered threads, which makes it NPT thread, at least according to what I read elsewhere. Is this original? Or did the mechanic who replaced it tap the hole for NPT thread? There is no fitting already there as far as I can see. I ask because the replacement as seen above is 1" SAE thread and does not fit so I am looking for an "increaser" fitting so the valve can be used. I checked the Dorman Products website, no luck, also local Ace hardware, same.
I am not new to the car but am a novice working on it , so thanks in advance for the wisdom of the crowd.

 

I think you have misconceptions about threads. SAE stands for Society of Automotive Engineers. They have published standards for many different things.

Basically, there are two general types of threads....INCH or METRIC specifications. In the USA the "Inch" measurement threads are common screw threads and pipe threads. Within "Pipe threads" are the NPT (National Pipe Taper) and NPS (National Pipe Straight). The two (NPT and NPS) can be inserted in to each other because they have the same number of threads per INCH and are similarly sized. The "fit and function" is vastly different if mixed.

Pipe threads are generally classed according to the INSIDE DIAMETER of PIPE. The actual measured size (OUTSIDE DIAMETER of PIPE) is larger than the "Pipe size".

Google this
"NPT thread size"

 

There are 2 different thread sizes on Olds heater valves. One for a valve that is normally open and closes with vacuum, and the other for normally closed and opens with vacuum.

Your 1977 should use the larger 3/4” thread one that uses vacuum to close.

The thread size is assuming your engine has the factory original intake manifold.

 

the manifold is original and is a 350 R code. The HCV I took out definitely has tapered threads, and the manifold has a larger than 3/4" hole, probably 7/8".And as I mentioned, the replacement HCV is 1", I have reached out to the vendor for comment. I will try to scare up a larger thread gauge than the one I have to get more accurate and complete info.

Thanks!

 

Correction, the manifold hole is 1", but I have doubts that the threads match, so I will go the thread gauge route

 

That is not entirely correct. The thread size changed with the 1971 model year. At that time, the full size cars and the Toro went to the normally open style valve, but the A-body cars retained the normally closed valve through the 1972 model year. These still had the newer thread size.

 

the HCV pictured above does not fit because it is 1 1/16" (straight thread), the intake manifold is threaded 1" - 14 fine thread pitch, as measured with a thread chaser.. Contacting the vendor proved fruitless. I contacted Four Seasons, all they can tell me is that their valves for these cars are 3/4" NPT. The conversion charts are confusing but I think that a 1" NPT is only 11 /1/2" thread pitch, not the 14 I need. Would a parts book help me?
Ideas? Suggestions? Thanks to all in advance

 

There are three valves pictured in this thread. Which one "pictured above" are you referring to? In any case, I have never seen one of these with straight thread, which won't seal in the manifold. All of them are NPT. 3/4 NPT is 14 threads per inch. 1" NPT is 11 1/2 threads per inch. I doubt you can tell the difference between 11 1/2 and 12 TPI with a thread gauge. One inch straight pipe thread is also 11 1/2 TPI.

https://hydraxio.com/thread-charts/

 

https://classicoldsmobile.com/forums...6/#post1057876 :

QUOTE=joe_padavano;1057876]I'll second this. In fact, I got so tired of replacing the leaking valves on my 84 Custom Cruiser that I put in a nipple and used a plastic Chevy style heater control valve. The Chevy valve has the external vacuum actuator, the plastic doesn't corrode, and since it's inline in the hose it's very easy to replace. Of course, that was a normally open style and won't work on the 72-earlier A-body cars.[/QUOTE]

And this may be it, could I please trouble you to elaborate on the Chevrolet valve? Or are they all the same (i.e. normally open)

That is if I can find a hose fitting with the 1" - 14 threads

Thank you very much!

 

The Chevy valve I used was for a same-year Caprice as was my Olds. The Caprice valve is for the 305 and is normally open. ACDELCO 155812