[Carousel72TRed]

Does anybody know from the factory for 69 GTO's with an automatic transmission if the vacuum advance with a Rochester Quadrajet carb was ported or direct manifold? Looking at a Rochester Quadrajet diagram it appears the connection where you hook up the vacuum advance on the front of the carb is above the bottom throttle body assembly which would be ported vacuum?

Carousel72TRed

[68gtoMN]

Vacuum canisters employ advance according to engine vacuum, which is why they must be connected to a ported vacuum source. Ported vacuum is drawn from just above the throttle blades to ensure the ignition does not advance at idle

[Kenth]

1968-69 Pontiac V8´s w/AT uses a thermo-vacuum-switch on the intake next to thermostat housing passenger side to control the vacuum advance.

The TVS-GM#3016754 is used on all 1968 V8's and on 1969 V8's with automatic transmissions. Also, several early production 1969 Ram Air III cars with manual transmissions were built using the TVS and the vacuum advance valve. The 1971 455 HO engine also used the TVS with either transmission.

In all applications, the TVS serves as a safety device to help prevent overheating. The switch is located at the front of the intake manifold, threaded into the coolant passage. There positions inside the TVS related to coolant temperature. Standard vacuum flow is ported vacuum from the carburetor to the distributor vacuum advance. Whenever the engine coolant temperature rises above 230 degrees F, the TVS switches the distributor advance from ported to full manifold vacuum. This advances the timing about 20 degrees at idle, allowing the engine to cool down to normal operating temperature. After the engine cools, the system returns to ported vacuum.

Also, most 1968-69 V8´s uses an idle solenoid for setting curb idle due to the retarded timing at idle speed to cure run-on (dieseling) at shut off.

Most 1967 and earlier engines did not have all this emissions crap, TVS, idle solenoids etc. 1968 and later engines needed due to the emission laws starting 1968.
They just ran manifold vacuum directly to the ignition vacuum advance.

[dataway]

If you use the TVS system, be aware of the Service Bulletin that removed the ignition retard function in late 68. They looped two of the ports on the TVS and only three hoses were used.

[Carousel72TRed]

Thank you to Kenth & 68gtoMN,

My TVS switch is currently unconnected and plugged off and I have seen pictures of the GTO engine bay with the looped vacuum line on it. Do you know the correct setup on the TVS like the looped line goes to which ports (middle & bottom, middle & top? And do you hook up the remaining port to both manifold and ported vacuum. And does it hurt to run vacuum advance on full manifold and not ported vacuum. You guys have been a big help to me and I appreciate your correspondence. I currently have a 3 port TVS switch that is not being used on my car.

Carousel72Red

[rockys1970]

If anyone is looking to purchase a nice used TVS, I just listed one on eBay today. Complete with the original vacuum hoses with loop.. See eBay Item # 274994557040. Or search user name rockys1970.
Others are available. Send me a PM.
Thanks

[Carousel72TRed]

Originally Posted by dataway

If you use the TVS system, be aware of the Service Bulletin that removed the ignition retard function in late 68. They looped two of the ports on the TVS and only three hoses were used.

Thank you dataway

[Carousel72TRed]

To All,

I found the plug/harness that attaches to the TVS that I bought a while back and the plug has the 2 ports to port DR and CR plugged off (no holes & top 2 ports on the TVS). The red striped hose goes to the rear vacuum fitting (power brake booster hookup) on the carb and the long hose (black) goes to the vacuum advance on the distributor. The line with the metal pipe goes to the vacuum break or choke pull off on a Quadrajet? and since I have a Holley carb would this might go to ported vacuum. I am assuming the bottom plug that says VT goes to straight manifold vacuum. If I am correct or not please let me know.

Carousel72TRed

[OG68]

PHOTOS ARE NOT MINE.

VT is vent and it should have a small cap on it.
You want to use ports 3-4-5 or CA - DA - M1.



Follow the photo below using hoses 3 - 4 - 5
3 is ported
4 to the distributor
5 is manifold

[Carousel72TRed]

Thank You OG68,
Now I have the complete picture.

Carousel72TRed

[dataway]

Wish I could figure out how to hook up mine on my 68 .... I've got a 704 carb (1971) ... doesn't have the same ported vacuum source of the 702.

[Carousel72TRed]

Originally Posted by Kenth

1968-69 Pontiac V8´s w/AT uses a thermo-vacuum-switch on the intake next to thermostat housing passenger side to control the vacuum advance.

The TVS-GM#3016754 is used on all 1968 V8's and on 1969 V8's with automatic transmissions. Also, several early production 1969 Ram Air III cars with manual transmissions were built using the TVS and the vacuum advance valve. The 1971 455 HO engine also used the TVS with either transmission.

In all applications, the TVS serves as a safety device to help prevent overheating. The switch is located at the front of the intake manifold, threaded into the coolant passage. There positions inside the TVS related to coolant temperature. Standard vacuum flow is ported vacuum from the carburetor to the distributor vacuum advance. Whenever the engine coolant temperature rises above 230 degrees F, the TVS switches the distributor advance from ported to full manifold vacuum. This advances the timing about 20 degrees at idle, allowing the engine to cool down to normal operating temperature. After the engine cools, the system returns to ported vacuum.

Also, most 1968-69 V8´s uses an idle solenoid for setting curb idle due to the retarded timing at idle speed to cure run-on (dieseling) at shut off.

Most 1967 and earlier engines did not have all this emissions crap, TVS, idle solenoids etc. 1968 and later engines needed due to the emission laws starting 1968.
They just ran manifold vacuum directly to the ignition vacuum advance.

It appears from what you are saying that it is OK to run straight manifold vacuum to the vacuum advance on the distributor because using ported vacuum was strictly for emissions. All my inquires have been for how my car was set up for originally from the factory and me possibly setting it up that way in the near future.

Carousel72TREd.

[Carousel72TRed]

Originally Posted by dataway

Wish I could figure out how to hook up mine on my 68 .... I've got a 704 carb (1971) ... doesn't have the same ported vacuum source of the 702.

I feel your pain. I went out to my toolshed and checked my old Quadrajet sitting on the rack to look at the vacuum connections and whether they were ported or straight manifold vacuum. Come to find out the carb is out of a 68 350 (7028269). I registered with Holley to try to get an answer on my vacuum connections on my Holley 750.

Carousel72TRed

[dataway]

On the test stand I just ran it straight to manifold vacuum, that's the way I ran it for years when I was driving it daily 40 years ago ... .and I suspect that's the way I'll be running it in the future ... maybe with some faux hoses hooked up to the TVS for looks.

[Kenth]

Originally Posted by Carousel72TRed

Thank You OG68,
Now I have the complete picture.

Carousel72TRed

Mind you that #1 and #2 hoses do not exist at all for 1969 Pontiac V8´s.

[Ram Air IV Jack]

Originally Posted by Kenth

1968-69 Pontiac V8´s w/AT uses a thermo-vacuum-switch on the intake next to thermostat housing passenger side to control the vacuum advance.

The TVS-GM#3016754 is used on all 1968 V8's and on 1969 V8's with automatic transmissions. Also, several early production 1969 Ram Air III cars with manual transmissions were built using the TVS and the vacuum advance valve. The 1971 455 HO engine also used the TVS with either transmission.

In all applications, the TVS serves as a safety device to help prevent overheating. The switch is located at the front of the intake manifold, threaded into the coolant passage. There positions inside the TVS related to coolant temperature. Standard vacuum flow is ported vacuum from the carburetor to the distributor vacuum advance. Whenever the engine coolant temperature rises above 230 degrees F, the TVS switches the distributor advance from ported to full manifold vacuum. This advances the timing about 20 degrees at idle, allowing the engine to cool down to normal operating temperature. After the engine cools, the system returns to ported vacuum.

Also, most 1968-69 V8´s uses an idle solenoid for setting curb idle due to the retarded timing at idle speed to cure run-on (dieseling) at shut off.

Most 1967 and earlier engines did not have all this emissions crap, TVS, idle solenoids etc. 1968 and later engines needed due to the emission laws starting 1968.
They just ran manifold vacuum directly to the ignition vacuum advance.

I've never seen a MT 69 GTO Ram Air or otherwise with a TVS switch. I owned a pattern RAIII MT Judge built in January 69 and that didn't have the switch. My June 69 MT Judge doesn't have one either. My understanding is the TVS switch was a AT application only but I suppose anything is possible. Since I've only owned MT 69 GTO's I wasn't aware of the TVS switches on the AT cars but saw them in magazine articles from that era..

[padgett]

I thought that was a TCS switch, Thermal Controlled Spark.

[Kenth]

TCS is Transmission Control Spark used 1970-74 on all V8´s but 1971 455H.O.

[Kenth]

Originally Posted by Ram Air IV Jack

I've never seen a MT 69 GTO Ram Air or otherwise with a TVS switch.

Me neither. Se page 6D-1 in 1969 Pontiac Service Manual.