1969 Cadillac NS vacuum connections

[Scot Minesinger]

I'm doing a mechanical restore for functionality on a 1969 Cadillac.  1969 and 70 are very similar mechanically.  The NS has it looks like 4 vacuum connections.  Of course two release the e-brake.  The shop manual is of no help, looking up NS and etc.  What are the other two connections for?  There are two light color striped lines (one looks white, the other tan), and the car was equipped with an electric cruise control, understand that late in the year the vacuum cruise was used like in 1970.  Maybe these had something to do with cruise?

[chrisntam]

Here's a recent discussion about the '70 NS, Bruce touched on the 4 ports, not sure if there is anything definitive in the post though.

http://forums.cadillaclasalleclub.org/index.php?topic=158892.msg454069#msg454069

Here's a post of one pulled apart.

http://forums.cadillaclasalleclub.org/index.php?topic=150245.msg396050#msg396050

[69Deville]

Hi Scot,

Glad to finally help you as you have helped in the past both directly and indirectly with all of your posts.

The white line runs through the firewall and is connected to the Idle Speed Up Device (page 6-73) that is connected to the back of the carb on the passenger side. It may have been removed and the hose might be plugged. This is how mine was when I got it.

The other line is green and runs to the thermal vacuum switch(page 6-42). Together, they activate the Idle Speed Up Device. It activates when the coolant reaches 220 and the car is in either Park or Neutral. They run to the NSS so it can activate the Idle Speed Up Device in Park or Neutral only.

[cadillacmike68]

I'm pretty sure the thermal vacuum switch only advances timing, by shifting vacuum from carburetor to manifold vacuum, and is independent of the transmission. Look at the manual.

The two extra ports on the Neutral Safety Switch, NSS (two Ss), Please spell these things out the first time an abbreviation is used, is strictly to pull on another diaphragm on the passenger rear quarter of the carbie, similar to the vacuum break on the passenger front quarter of the carbie. This in turns moves the fast idle cam. It only does this while the Climate Control is in an auto type mode (not OFF or VENT) And the transmission is in Neutral or Park, which is why the ports are located on the NSS.
Not all 1969s have this feature and only a very few 1970s have it. Again, details are in the manual, but I think all 1968s have it.

[69Deville]

I'm pretty sure the thermal vacuum switch only advances timing, by shifting vacuum from carburetor to manifold vacuum, and is independent of the transmission. Look at the manual.

The idle speed up only engages when the temp exceeds 220 so that’s why the vacuum line runs from the thermal switch first then to the NSS (green line) and then from the NSS to the idle speed up (white line). The thermal switch provides the temperature and the NSS engages only in Park or Neutral. This is why the 69 uses a four port thermal switch instead of a three port. The shop manual outlines it in the page I cited and I have the setup in my 1969. I believe most people tossed the idle speed up long ago and just plugged the white line in the engine bay.

[Scot Minesinger]

69 DeVille: Perfect, exactly what I needed.  This is a 1974 engine in the 1969 Cadillac DVC (highly modified) with a 1976 carb (electric choke).  So, not worried about abandoning it now.

Thanks,

Scot

[cadillacmike68]

They just Had to complicate it further in 69. 

[Scot Minesinger]

1970 Cadillacs are an oasis of less complications, mechanically in the 472/500 family from 1968-76:

1.  No air pump
2.  No EGR
3.  No exhaust pipe butterfly valve heat riser to stick shut closed
4.  No idle speed up or complicated anti-diesel carb issue to deal with
5.  Fixed fan blade that flattens at speed - no fan clutch
6.  Inspection plate on differential

It does have the timing retard solenoid which is easily by-passed (retards timing in 1st and 2nd gear except at heavy throttle).
It does have the problematic snorkel damper warm up in air cleaner housing which is also easily made non functional

Last of the high compression V-8's that runs on unleaded (not designed that way) premium just fine.

[cadillacmike68]

1970 Cadillacs are an oasis of less complications, mechanically in the 472/500 family from 1968-76:

1.  No air pump
2.  No EGR
3.  No exhaust pipe butterfly valve heat riser to stick shut closed
4.  No idle speed up or complicated anti-diesel carb issue to deal with
5.  Fixed fan blade that flattens at speed - no fan clutch
6.  Inspection plate on differential

It does have the timing retard solenoid which is easily by-passed (retards timing in 1st and 2nd gear except at heavy throttle).
It does have the problematic snorkel damper warm up in air cleaner housing which is also easily made non functional

Last of the high compression V-8's that runs on unleaded (not designed that way) premium just fine. 

I have implemented # 1 and #5 on my 1968 and #3 the exhaust butterfly valve works fine as does #4.  I don't think there was an EGR  back in 68. I do like these aspects of the 1970 cars.  The ability to easily check and drain the diff (#6) was a nice addition, but not critical.


But you don't have a V with your front and rear crests 

and no vent windows/ 

[Scot Minesinger]

Mike,

Recommend removing the ability for your exhaust pipe heat riser valve to block exhaust flow.  If it fails, you probably will overheat in FL especially and it will take out your carb to intake manifold gasket, resulting in a very poor engine running.  Why risk it?

Just speaking mechanically, the 1970 is a winner for sure.  The 68 has the real wood on doors and dash, vent windows, and I like the dash better than a 70.  The 70 seats (along with 69) are really nice with the high backs.  Optimizing my choices: 67 interior (door panels especially cruise control switch) with 68 wood accents, 69 Fleetwood seats, 70 mechanicals (except no timing solenoid), 67 rear bumper ends, 68 middle bumper, 70 front end (I can live without the "V"'s) and of course a DVC.  then add 8 piece modified (cut) Fleetwood rocker moldings.

[chrisntam]

The '70 steering wheel blows (and that's not a good thing).