Puppy boy

Just curious about the restriction in the end of the vacuum modulator line at the carb end on a 1970 442 455.Apears to be factory installed.Thanks

RetroRanger

I dont think ive ever seen that any pic?

Fun71

Hmmm. My vacuum modulator line connects to an intake runner, and not the carburetor.

Vintage Chief

Mine, as well - intake manifold port connection.

rocketraider

Puppy, are you in CAlifornia or CAnada?

If you're in California and the car was originally delivered there, there's no telling what kind of weird emissions stuff it might have including transmission vacuum source.

Also, no telling what some prior owner or mechanic might have done in last 50 years.

Can you show us a picture of this strange vacuum line?

Puppy boy

Hi Im referring to the end of the metal line that is by the carb not the trans, and yes no matter were you hook it to the metal line has tiny crimp marks at the end which appears to be holding a restriction in the end of the line. I am 99.9% this is as it came from the factory. Try to put a small drill bit in the end of your stock modulator line . Thanks

Puppy boy

canada, I"ll get pictures if need be .Thanks

Vintage Chief

I assume you are referring to the automatic transmission modulator line when you state vacuum modulator line?

The reason pictures would help is so we can validate (1) that's what you're referring to & (2) the routing of your automatic transmission vacuum modulator hoses. Don't quote me to be correct on this, but I believe the CSM refers to the OEM vacuum routing connections to/from the Transmission Thermo Vacuum Switch (TVS) (referred to prior to 1971). In 1971 this switch is referred to as the DVCS (Distributor Vacuum Control Switch). There were differences how these switches were designed throughout the years. The latter years incorporating an electric solenoid on top of the DVCS. I don't know if your 1970 has a solenoid on top. Never-the-less, my point is this. You're referring to a "restriction" at the end of the line & I'm assuming you're referring to the end of the "metal" line or are you referring to the end of the vacuum hose line which runs off the metal line? Where I"m going with this (and the reason we need pictures) is because on different vehicle models, different engines (350 vs 455), 2bbl vs 4bbl and w/ or w/o AC the vacuum routing is different. In fact, the solenoid location is different, as well under various configurations. There is a "T" employed which looks like a constriction and could be the constriction you're referring to. Did someone (a PO) install this "T" in the incorrect location? Possibilities abound.

"Good" pictures of the vacuum routing hoses would assist in helping you. There's a possibility a PO changed the OEM configuration of your automatic transmission modulator vacuum lines or maybe (attempted to) eliminate the TVS (Transmission Vacuum Switch) altogether.

Do you own the CSM for your vehicle? The various configurations are listed at the end of Chapter 6 - Engine Cooling. Review the diagrams of the various engine configurations and vacuum line routing.

You might review these two links to get an idea of the DVCS (TVS) modulator vacuum line configurations.

These images are not for a 1970, but will provide a general overview. Refer to your own 1970 CSM configurations.
Post #3 of the following thread:
https://classicoldsmobile.com/forums...switch-136282/
https://classicoldsmobile.com/forums...-switch-39559/

Vintage Chief

I meant to say Thermo Vacuum Switch (above post)...my bad. It's late, my mind is tired. I corrected it in my post (above).

Vintage Chief

It appears you have been provided some information regarding your particular issue as it relates to the electrical wires for your modulator? I think you need to continue along this theme and evaluate the hoses with greater detail.

https://classicoldsmobile.com/forums...arness-154590/