I can't seem to find where the modulator line connects to the intake. I don't see a clear pic of it in the manual. Mine is connected to a fitting with 3 ports on the front pass side. Just wanted to verify it from the manual for a 70 442. Any help please?

 

Functionally, any intake manifold nipple is fine.

As far as obsessive originality, usually the Assembly Manual will show a picture. If not, then another member probably has the answer.

- Eric

 

If the three port vacuum connection on the intake is anything like on my '73 Custom Cruiser than you wouldn't want your trans line hooked to it. That three port connection is a thermal vacuum switch that modulates the amount of vacuum based on the engine temperature. Really just used for emissions purposes.

My trans modulator hose is connected to the carburetor but just as Eric said, any continuous vacuum source would suffice.

Chris

 

The reason I was trying to find out where it originally went is because I am having problems with shifting. I was thinking maybe the mod vac line should be by itself and not split by a three port fitting.

 

To repeat: Any intake manifold nipple is fine.

If the nipple is on the manifold, it is good, and it MAY be where the modulator was connected originally.

If the nipple is on something other than the manifold, it may be wrong, depending on exactly where it is.

- Eric

 

As stated above the modulator needs manifold vacuum to operate correctly. Normal symptoms of improper shifting would usually be not shifting into higher gears until the engine reaches an abnormally high rpm or when your slowing down it would feel like you were rear ended when it dropped into lower gears.

 

I would like to see where the manual shows it should go but I can't find it.

 

You haven't looked very hard, have you?


1969 Oldsmobile Cutlass Assembly Manual:



Note you can see the end of the modulator vacuum pipe sticking up where it ends by the valve cover.





Now note that this shows the air cleaner vacuum hose going to the fitting right in front of the distributor.





You can see here that the modulator hose curves around counterclockwise, from the end of the pipe next to the valve cover, to where it Tees into the line going to the barb between the thermostat housing and the carburetor.



1969 Oldsmobile Chassis Service Manual:



You can see here the modulator hose going directly from the end of the modulator pipe to the barb between the thermostat housing and the carburetor.

- Eric

 

I looked thru the manuals at least 3 times. Sorry, my eyes are not as good as they used to be. All i can find is a pic like the first one where it ends by the valve cover. Thanks, great info if it was for a 70 like I asked for.

 

On my 69 2bbl it is connected to an intake manifold nipple in front of the distributor.

 

Sorry, I was just busting your chops.

You really have to know what to look for in the Assembly Manual, because it's all kind of hidden.

I only found it because I have skimmed through all if the Assembly Manuals, and I have a bit of a photographic memory, so I knew where to look.


Ummmmm... I thought you wanted info for a '69, like in your name.

Doesn't matter - '69 and '70 should be the same.
You can go to the same page numbers (included at the ends of the file names) in the '70 manual to confirm if you'd like.

- Eric

 

Which will work fine, but when the factory made it, they wanted the air cleaner vacuum hose to go there.

- Eric

 

Thanks Eric, Like you say, the third pic shows it going to a Tee and then to the barb between the thermostat housing and the carburetor (which mine is plugged). The other line off the Tee goes to the bottom barb of the 3 port fitting (which is where mine is attached). So it looks like it comes off 2 vac ports and Tees to the mod line. Is that how you see it?

 

There is a hose barb in the intake manifold and that is the vacuum source for both the thermostatic switch and the modulator. The purpose of the tee is so that the two elements can each have a direct vacuum source. Do not connect the modulator to any of the ports on the thermostatic switch; make sure it has its vacuum source coming from the manifold barb.

Can you elaborate on what exactly is plugged? Your wording was not clear.

 

Can you elaborate on what exactly is plugged? Your wording was not clear.[/QUOTE]


The hole in the manifold that has the fitting by the tee. That has a square plug in it.

 

So are you saying that there is no manifold vacuum source for the "3 port fitting"?