400 block vacuum line question

[jonny0666]

Hey. Dumb question. I’m sprucing up this 400 block that came in my Road Runner. What are these vacuum valves for? (Attached picture) And do I need them? Please and thank you.

 

[Lefty71]

Hard to answer this one without knowing more about the car, and its intended use. Pure stock original motor in a show car or preserved original, then yes. Pro street or even mild rod, then probably not. I'd have to get out a schematic to be sure, but I thought one involves the air doors on a factory air cleaner assy. and the other isolates the retard box on the distributor for '71?? Not too positive without knowing the exact application and model year. HTH, Lefty71

 

[beanhead]

.... isn't that the water pump housing? Hard to tell looking at it on my phone but that's usually where the heater nipples plug-in? One looks like the temp sending unit. Then again I've never had a 400, so...

 

[jonny0666]

Yes, that's the front of the engine. just to the passenger side of the Distributor. It's a 400 block from a later model car, 73-74 i believe. I've got 1000 pictures before i tore the motor down, and of course, that's the one angle i don't have.

 

[beanhead]

Okay so hopefully somebody more knowledgeable with the later B blocks will chime in, but I'm almost positive those aren't for vacuum... vacuum would be coming from the intake and carb. It appears to me anyways, that the two taped off fittings outside of your circle are the heater hose nipples, and then the stuff on top is a temp sender and I'm not sure what the one is that has the little hose on it dot-dot-dot but it's basically just acting like a plug anyway so maybe somebody just stuck that on there?

 

[Lefty71]

I looked at two different complete motors from ~73-74. One was a 400 and other was a 440. Neither quite matched what you have, nor did they quite match each other. They are indeed vacuum valves. They change port valving based on water temp. Yet one of mine had the temperature sensor there just like Beanhead said. One I looked at went to an electric solenoid by the back corner of the Thermoquad, and another port went directly to the vacuum advance on the distributor and the other port went back to the manifold tee ftg at the back of the intake. The only way to be sure is look at the emissions sticker, or the diagram in the service manual. I have the diagram for a '72 400 here, so ill have a peek at it and then repost. HTH, Lefty71

 

[HALIFAXHOPS]

Thermatic switches for vacuum control. Not sure their purpose but usually allow vac to flow or not due to temp changes. Mostly emmissions I believe.

 

[HALIFAXHOPS]

I looked at two different complete motors from ~73-74. One was a 400 and other was a 440. Neither quite matched what you have, nor did they quite match each other. They are indeed vacuum valves. They change port valving based on water temp. Yet one of mine had the temperature sensor there just like Beanhead said. One I looked at went to an electric solenoid by the back corner of the Thermoquad, and another port went directly to the vacuum advance on the distributor and the other port went back to the manifold tee ftg at the back of the intake. The only way to be sure is look at the emissions sticker, or the diagram in the service manual. I have the diagram for a '72 400 here, so ill have a peek at it and then repost. HTH, Lefty71

Sounds like CAP, actually makes sense.

 

[beanhead]

Thanks guys, I figured smog-related stuff if anything...water temp-controlled valve for vacuum from a different source...makes sense now

 

[jonny0666]

Got it. Well my temp sensor is below there and vacuum advance was off the manifold tee... so cap and see what happens. Thanks all.