Emission Control or lack there of

First and foremost I want to thank you OG for the warm welcome. It's nice to see these rocket motors have such a huge following, not to mention knowledgeable enthusiast.
Now to the meat and potatoes. Fury here, with the 72 Cutlass, 350 Rocket. I was undergoing a resto job utilizing the stock air cleaner assembly with an Edelbrock Carb. On the air cleaner assembly are 2 vacuum hoses: one to the vacuum diaphragm motor from the temp sensor, and the other vacuum hose is routed to the intake manifold tee. Now pardon my ignorance, but where the heck is the manifold tee located so I can plug this puppy in?

[Bluevista]

On my '71 350 with a 2 barrel there's a brass right angle vacuum fitting on the top of the manifold between the carb and distributor for that hose.
Illustration from the Olds chassis service manual sort of shows it.


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[rocketraider]

Are you still running the original cast iron intake, or have you also changed it? sometimes aftermarket intakes don't have enough vacuum ports to duplicate factory stuff.

The factory routing for the ThermAC went to an orificed fitting screwed into the intake, behind the carb. It's a straight fitting with a very small orifice, about the size of an 0.3mm pencil lead.

Blue, Double R, thanks bros. It would appear the previous owner had it capped off with some sort of nipple cap. Other than being lazy, not sure why, however, he/she wasn't very meticulous about auto mechanics (air cleaner was rusted/ vacuum tubes were unassigned/ rotten).

[Bluevista]

Cool avatar, that is Christine. I never miss that or Maximum Overdrive when on TV. My neighbor friend's dad had a finned Dodge-something when I was a youth and we always thought the swiveling seats were about the coolest thing ever.

Now on to the TCS control switch (left of thermostat water neck). I have one intact utilizing my stock intake manifold, but it has no vacuum tubes running from it to the usual spots/switch (rear carb, distributor, front carb, switch to vacuum). Question, do i need to utilize that? I have an Edelbrock carb so the front and back carb switches aren't applicable. The distributor is running to the E.carb instead of the switch, and there's nothing running from the switch to vacuum. I was thinking of capping them off, but I want to make sure she's optimum. Any ideas Blu, RR, Joe P?

[ScottAndrews]

I'm wondering about that vacuum switch myself. As I understand it, it's supposed to shutoff vacuum to the distributor until a certain coolant temp is reached. The Boss's '72 Cutlass convertible still has this switch in place but, like yours, the vacuum lines have been removed, probably by the previous owner that replaced the stock distributor with a later HEI unit. The real head-scratcher, at least to me, is the purpose of the two-terminal plug hooked to the top of this thing; I have no idea what it electrically connects this vacuum switch to!

Regards,
Scott Andrews

[joe_padavano]

Originally Posted by ScottAndrews

I'm wondering about that vacuum switch myself. As I understand it, it's supposed to shutoff vacuum to the distributor until a certain coolant temp is reached. The Boss's '72 Cutlass convertible still has this switch in place but, like yours, the vacuum lines have been removed, probably by the previous owner that replaced the stock distributor with a later HEI unit. The real head-scratcher, at least to me, is the purpose of the two-terminal plug hooked to the top of this thing; I have no idea what it electrically connects this vacuum switch to!

Regards,
Scott Andrews

The thermal vacuum switch (TVS) is intended to switch the distributor vacuum advance from ported vacuum (which is zero, or no advance with the throttle closed) to full manifold vacuum if the engine starts to overheat. Applying manifold vacuum at idle increases the advance, cools the engine, and speeds up the idle a little. Many people bypass this system and just run full manifold vacuum to the distributor at all times.

The electrical contacts are an added function related to the transmission controlled spark (TCS) system. TCS was an early emissions control system that attempted to reduce NOx emissions by eliminating any vacuum advance in all gears except the top gear. A switch on the trans activated a solenoid valve in the TVS that allowed the vacuum advance to operate when the trans went into high. Since eliminating vacuum advance in the lower gears could lead to overheating, the thermal part of the valve still functioned to apply full manifold vacuum to the distributor if the engine started to overheat. Again, most people have disconnected this sytem. In prior years the solenoid valve was separate from the TVS valve, but by 1971 they were integrated in one unit to save cost.

[ScottAndrews]

Joe,

Thanks for your quick reply! It sounds as if I can ignore this thing at this point in time, or remove it and plug the opening should it start leaking... that is, unless I ever decide to head down the factory correct restoration route. In that case, I know I'm going to have some fun locating the correct part. None of the auto parts stores, nor any of the restoration parts vendors for that matter, seem to have a TVS with the integrated solenoid valve.

Thanks again,
Scott

[ScottAndrews]

nm

[ScottAndrews]

nm

[ScottAndrews]

nm

[ScottAndrews]

...crossing his fingers as he awaits THE BRIGHT LIGHT and the swinging open of THE PEARLY GATES to Oldsmobile Heaven....

[marty]

I believe my 83 H/O is a classic this year. 25yrs?
Doesnt seem right. I'm looking for Documention or ref (pics) on plumbing under the hood. All the emission stuff is stripped off ,yet the rochester E-carb is on with no connections. Im going with a stocker for know.