[Verdoro 68]

We have a bunch of rotten and missing vacuum lines to replace on our '74 Ventura. I'm not well versed in smog-era Pontiacs. Can anyone tell me what this thing on the intake does? The vacuum lines go to the advance canister on the distributor and the carb. It's clearly missing a vacuum line on the front, but I'm not sure where it's supposed to go. Is it some kind of solenoid that manages vacuum advance?

[b-man]

TCS solenoid.

Transmission Controlled Spark.

[Verdoro 68]

Do we need it? The whole TH350 setup is new to me too so I’m not sure what’s what.

Looks like it's not awesome for performance if it's blocking advance in first or second gear.

TCS: transmission controlled spark, an emission device that controls the operation of the distributor vacuum advance. When the engine is below 63 degF or above 232 degF, or the transmission is in 1st or 2nd gear, the solenoid will block the full vacuum signal to the distributor. The signal is not blocked for 15 seconds after starting the engine to prevent stalling. The TCS system is not required unless you are seeking originality or need to pass an emission test.

[steve25]

Don’t use it, but don’t toss it either.
Someone might need it for a resto job.

You have the most remaining yellow paint that I have ever seen on those duel throttle springs for a car that was by not mothballed.

[77 TRASHCAN]

One of the vacuum hoses went to a solenoid (?) on the transmission. It screws into the trans real close to the Trans dipstick. If that part is still attached to the trans, its likely leaking. Remove it, replace with a 1/8" pipe plug. use teflon tape on it..

[mgarblik]

That solenoid is very hard to find with all the plastic nipples still in one piece. Worth even more if it actually still clicks when energized. In conjunction with this solenoid is a cylinder head temperature switch which screws into the left cylinder head at the rear in a regular 3/8-16 bolt hole. DO NOT TOSS then in the trash. Someone restoring an SD-455 would pay $$ for those two pieces in good condition, especially working ones. (How do I know?)

[Verdoro 68]

I'm surprised how much of this car is original considering how many miles are on it (100k). I replaced the PCV yesterday and I'm pretty sure the hose for that (which was rock hard and very crispy) was original. I've never seen a spring retain that much of it's original yellow either. This car was just a commuter for years so it was just maintained and not mucked with. We found a few receipts for work done in the late '90s replacing a handful of parts here and there to keep it on the road.

The trans is leaking pretty bad. I thought it was the pan gasket, but maybe that solenoid is contributing. As of right now, all the hoses for the advance are rotted through or uncapped so it's safe to assume it's getting no advance at all.

[Held for Ransom]

Originally Posted by Verdoro 68

We have a bunch of rotten and missing vacuum lines to replace on our '74 Ventura. I'm not well versed in smog-era Pontiacs. Can anyone tell me what this thing on the intake does? The vacuum lines go to the advance canister on the distributor and the carb. It's clearly missing a vacuum line on the front, but I'm not sure where it's supposed to go. Is it some kind of solenoid that manages vacuum advance?

Not missing a hose, but a sponge filter.
http://www.forums.maxperformanceinc....d.php?t=665429
Link to a link to the '74 emissions booklet.

[ponjohn]

I just bought this 74. I am going to see if mine has that.
Mine is 350 2bbl.

[Held for Ransom]

Originally Posted by ponjohn

I just bought this 74. I am going to see if mine has that.
Mine is 350 2bbl.

If still stock, it should.

[ponjohn]

Originally Posted by Held for Ransom

If still stock, it should.

It is, even has the cold air hose to the air cleaner.

[Held for Ransom]

Originally Posted by ponjohn

It is, even has the cold air hose to the air cleaner.

Don't go breaking that duct piece bolted to the core support.

[Verdoro 68]

Originally Posted by ponjohn

I just bought this 74. I am going to see if mine has that.
Mine is 350 2bbl.

NIce! Looks like a Sprint, too.

I had to sway the rear carb fitting for one that works with power brakes this afternoon, so took the opportunity to unhook all the TVS stuff. I ran a vacuum line direct from the advance to a ported source on the carb. Given the condition of the hoses, I'm sure it really wasn't doing much except serving as a giant vacuum leak. Original striped factory hoses with the friction tape - just severely cooked. I'm assuming the pic below is the temperature switch that mgarblik mentioned.

[Held for Ransom]

Originally Posted by Verdoro 68

I'm assuming the pic below is the temperature switch that mgarblik mentioned.

Yes, that's the temperature switch. But, mgarblik was probably talking about the cold feed button switch at the back of the head on driver's side.

[Verdoro 68]

I’m sure that’s still there too. I’ll take a look next time we had over to the shop. I’m 99% sure the engine has never been apart.

I never realized how different a ‘68 and ‘74 were. I’m getting schooled. I went to use the wire looms off my ‘68 on the car last night and there was no place to mount them on the heads!

[Held for Ransom]

Nope. Just plastic wire separators in '74.