I've been reading up on the summer ventilation system in my Oldsmobile because nothing is hooked up. I have small black air tubes dangling about, green, blue and black wires with connector ends just hanging under the dash. I wanted to attack this portion of the car so that I can check off another system that has been taken care of. My question is: Does the heating system need to be operational for the summer ventilation to work? I gathered that it does, from some reading in my CSM. I have no heater core installed and no hoses from the water outlet of the water pump to the heater core connection on the firewall. I have things capped and blocked off because I don't drive the Olds in the winter or cooler months ever. Does anyone have any experience with messing with the summer ventilation and the heating system? My blower motor works, I ran switched power to it, and it hums right along. Just thought it would be near to be able to use that summer ventilation on those warm, cruisin' summer days.

Thanks guys.

 

Most of the system is run by vacuum. If you follow the heat/vent diagram in the CSM the vacuum is provided by the fuel pump. You might be able to get the floor vents to actuate alone by plugging off the lines that go to the heater portion. Without knowing or seeing what remains of the system I wouldn't be able to help you further.

 

I don’t have the upper vacuum portion on my fuel pump! I just have the bottom 2/3 and that top half is blocked up with a plate. Interesting! Maybe I should find a NOS fuel pump with the top vacuum portion

 

I was having trouble with the vacuum side of my fuel pump and sort of by passed it temporally, I'll take a look at it tomorrow and let you know. I know my summer/ventilation is working as of now, I forgot how I ran the lines.

 

This is what the mechanism looks like inside the dash for the heating side, the summer side is a mirror to it. The tips on the side is where the vac lines go and are numbered so if you follow the CSM diagram you can match up the colors to the numbers. The vac lines have a color stripe on them.
It's really tight in there and the best way to work it is use a hand mirror and a good light.

 

Thanks for that! That makes complete sense now. So, at this point, I should probably find a fuel pump with dual action to get that ventilation to work. Thoughts on that?

 

Wait till I check my car tomorrow.

 

I will wait Art. No rush. I appreciate you doing the legwork for me here.

 

I'm back.... Do you have the trunk release in the glovebox? There's a can on the firewall where a vac line would hookup to the can and that's where I put the main vac line that would've gone to the fuel pump on mine. If you don't have that can try making a tee as shown in this diagram that's to the left on the carb.. Instead of the hose they show that goes to the can run the main heater vac line there. Then inside plug off the lines you won't be using for the heater part. What the buttons do when you press them is it closes doors inside the heater box and opens other ones to redirect the air flow. It will open the doors on the floor vent doors for more ventilation. But make sure the vacuum lines are good because you could end up causing a vac leak to the carb and or manifold.
I'm outside waxing the car right now so I'll check back later and see how you're doing.

 

So I do not have that canister or a trunk release in glove box. I’ll have to try the tee method. I’ll get some pics and post them here to show you my setup.

 

 

A few things I noticed from your pics that you might want to address to help make the car run better.
Did you explain one time why you have all those gaskets stacked under the carb? Do you have trouble cold starting it? because you are missing the tube that goes from the choke housing to the manifold. The tube provides heat to that housing from the manifold and inside of it there is a heat coil that automatically moves the choke plate to the open position as it warms up (see attached image and zoom in, sorry about the blurry piic

The carb looks like it's from some other year? One of the screws on the carb has split the housing, the one to the left of the fuel inlet and it looks like there is fuel leaking in that spot and it's wet on the base below that area and is pooling up on the manifold. Please don't take this as criticism, I'm just trying to help you out.
There's a small grounding strap at the back of the engine that connects to the firewall that you might want to check and make sure it's got a good clean surface on the motor and firewall to make it a good ground.
I see you still have the heater box and you could hook the fan wires back up and the vacuum line and that'll give you a fan for the defroster even though you won't have heat to it.
That's enough for now...

 

Glad you brought those things to the thread here. So, the stack of plenums was to address the vehicle running poorly when heated up quite well, on hot days. I figured I would give the carb some space between the intake manifold and itself to lessen the heat getting to the carb. It has worked quite fine, I think. Any reason to delete them and go back to the single gasket between the carb and manifold?

I pump the pedal three times, crank it, and she fires right up. Never had any cold start issues, even on cooler days. Not sure If I even have a port for a fitting that would thread from the choke housing to the intake manifold.

The small pool you see is actually oil, somehow. I dipped my finger in it, and it smells nothing of fuel. Not sure how that could be happening, but it is a small leak of oil.

As for the crack, I see what you are seeing in my pic. It is actually some 'un-burred' casting. There are no cracks on this carb that I've come across yet.

I will take any suggestions and criticisms. I very much appreciate it because it will help me better understand how things work, and it may help the thing run even better. Let me know Art, suggestions are always welcome!

 

Some more pics. Looks like the hole on the intake is plugged, no threads.

 

This is the choke tube I'm referring to. You can see in one of the pics how it just presses into the hole on the manifold. The hole is there on your's it's hiding behind the wires and vac hose along the edge of the valve cover. In the second pic I can see half of the hole. https://www.ebay.com/itm/14520868377...Bk9SR-7C3ef3ZQ
Gaskets - if it works for you, great. It's just that I've never seen that before. As far as starting procedure on mine, I pump the pedal once to the floor, it runs at high idle and after a minute or two I tap the pedal and the idle drops to about 600 rpms and then after the engine warms up some more (thermostat opens) tap it one more time and it goes to 450 rpms.
Let me know how you do with the vent stuff.

My shoulders are killing me from the washing and waxing.

Last fall.

 

Gorgeous Olds! Wow! I am going to search for one of those tubes and get it hooked up. The point of those is to hear the coil inside the choke housing correct? I will let you know about the ventilation. It may not be for a little while yet, but it’s on the list of ‘to-do’.

 

Thanks. Yes it heats the coil. On the underside of the manifold there is a tube running from one side to the other, the other end is closed, and it feeds hot air to the tube. I should do some videos of this stuff and post it to youtube, but I'm kind of self conscience and hate seeing and hearing myself when recorded and I can't keep the camera steady, lol.

 

Oh I hear about the videos man, I’m the same way. I could probably get some 3/8 tubing or whatever size the hole is, and double flare the end that connect to the choke housing threads with a nut right?

 

Yea that would work. You just have to figure out what that nut thread is and make the bends without collapsing the tube. I think the nut is the same as the ones for the fuel pump and the tube is definitely not 3/8. A simple flare will work because it's not critical to seal up tight like a vacuum.

 

I’ll get it measure out tomorrow and I’ll use mock something up. And thanks for the sealing tip, a single flare should do the trick. I will take pictures of the setup when I’m all done. Most likely get started after work is done for the day, so tomorrow evening or later this week. Thanks Art.

 

You're welcome, have a good night.

 

might be 1/4” OD tube? Could you possibly get a measurement of the diameter tomorrow for me? I had some 1/4 tube laying around and the proper thread fitting. Something like this? How far in should the tube be pressed inside the hole on the intake? This is just a mock up.

 

Mike - Great support from Art. Your choke is currently non-functioning w/o use of the heat choke tube which normally supplies the warm air from the intake manifold into the choke. Ensure your choke thermostatic spring/coil is properly engaging the choke cover plate. I note the cover plate is significantly overclocked to the RICH condition (side). You're going to likely have to make an adjustment to ensure the spring/coil is clocked correctly once you insert the heat choke tube & begin to supply warm air. Just mentioning it. Likely loosen &/or remove the choke cover plate, ensure it's engaging the spring/coil correctly, ensure the spring/coil is in good condition. The heat choke tube will insert into the manifold orifice to a depth necessary to secure the flared nut onto the choke.

 

Thanks for jumping in and helping out Norm. Correct on the position of the plate. There's a scratch mark that is supposed to be aprx in the middle of the bracket area. Also the hold down clips are backwards - they have a curve to them and when they get pressed against the plate they keep the plate from moving.

 

Art and Norm, thank you both for all the info! You’re continuing to feed me knowledge. I surely appreciate it.

 

The end of the tube going into the manifold is 19/64" and the nut going onto the housing looks like 3/8" ID of threads. Here's what the dimensions are aprx. This pic is from the one on ebay.

Heat choke tube for Rochester 4gc Carburetor.

 

Is the manifold end of the tube going to have to be widened a bit to fit snug into the orifice? 1/4” doesn’t fit as snug and 19/64 is damn near .3”. Is there tubing that is 19/64” in diameter?

 

I don't have a micrometer to measure it. The end of the tube fit into a gauge and the reading was 19/64". I guess if you need it a little tighter you could heat it up and push a drill bit into it to spread it. If easier to read it's 7mm OD. That is on mine, yours might be different.

 

Here’s what I came up with. Seems to work OK.

 

Good job and saved yourself $40 bucks. Now if you feel like it do the adjustments from the carb section of the CSM.
Now onto the next project, lol.

 

Art already provided the textual framework. I'm basically repeating what Art stated w/ a different image.

I know for a fact it gets colder than a witches tit in a brass bra face down in the snow in Northern Minnesota - for a long time during winter months. Let's ensure you setup the choke correctly before next winter; so, let's try this again.

(1) NOTE: There is a raised solid line located on the choke cover plate which the blue arrow points to. It is that raised solid line which should align between the Rich/Lean gradation marks I've annotated in yellow at the TOP of the choke. That raised solid line should align w/in those gradation marks (the red line demonstrates you should clock/bump your thermostatic spring/coil & cover plate clockwise to the right (red arrow) for alignment. This is why I stated to remove the choke cover plate completely. Look/Examine/Review the choke thermostatic spring/coil mounted under the choke cover plate is aligned into the notched key way at the center (underside) of the choke cover plate. IOW, that new intake manifold choke stove tube will be useless unless the warm air it provides is able to enter and heat the thermostatic coil/spring.

(2) So, align that raised solid line located on the choke cover plate w/in the gradations at the TOP of the choke.

(3) You'll want to completely remove the choke cover plate, ensure the cover plate is correctly aligned in the thermostatic coil/spring key way so the spring/coil actually begins to work for you during the winter months. When winter does finally arrive, you don't want to be pissing around with that spring/coil to ensure it's catching and aligned correctly. Right now you're WAY overclocked in the CCW direction. Make sue the spring and cover plate are working together. You'll only need to loosen those three hold-down screws to make a minor adjustment RICH or LEAN when the snow falls.

 

I've owned plenty of cars in the Great White North to know it's far nicer to be able to start the car then walk indoors to wait for the engine to warm up as opposed to feathering the accelerator pedal for 5' - 10' each time to keep the engine running until it warms up on its own. I mean, if you're going to have a choke (now w/ the correct intake manifold choke tube), hell why not use it?

Those thermostatic springs/coils are readily available if yours is Tango Uniform.

 

Awesome, thanks for the detailed explanation, Norm. That helps. I know just a little but more about the choke housing and those gradation marks now. Going to remove the cover and inspect the coil inside and adjust things how you instructed.

 

This is unlikely your coil/spring - but should be similar. I just happened to have an image (as example only). If yours is broken, rusted to pieces or not even engaging it's just an item to take note of.

 

some pics of what I have. Looks all good to me yea?

 

Mike - Actually, the spring/coil is in excellent condition. Ensure the spring/coil aligns with the choke cover plate. You'll gain some familiarity as you turn the choke cover plate CW (lean) &/or CCW (rich) when engaged into the spring/coil as you ever so slightly put the choke cover back on you'll see which way the spring/coil should be moving as hot air from the intake manifold choke tube heats the spring/coil causing the spring/coil to expand. You got it.

 

Thanks Norm, you are so much better at explaining things than I do and you use those drawing programs way better too.
There are quite a few steps to follow when setting these carbs up and making the adjustments and the instructions can seem to be a little confusing but when they are set up correctly they run great.
I know from experience it's no fun trying to make these adjustments in the freezing cold when the car won't stay running.

 

Art - That's the truth.