When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Tech Editor's DeskProjects, papers, writings, thoughts, musings of our technical editor Joe Padavano. To begin with, he will be making threads and can approve posts to it if he wishes. This can be changed in the future if it does not work out well.
I am a new Oldsmobile owner. Recently purchased a 72 Cutlass S (350 & Auto)
I have not had any previous experience with the 350, and I have not purchased the chassis service manual yet. That will be one of my next purchases.
I discovered on my vacuum switch that I have one line coming out of the top, going to the carburetor. The other three ports are open with nothing connected.
Should the three ports that are unused be capped? Would the chassis service manual be any help as far as vacuum and diagrams?
It will, but until you get it and figure out which vacuum switch this is, capping the open ports is a good idea to avoid a vacuum leak. If you can post a pic we can ID the switch.
They probably bypassed the temp controlled spark advance to the distributor. I would remove the line at the carb and cap the port until you figure out what you want to do.
The switch is the thermal vacuum switch (TCS). Haven't figured out what TCS is the acronym for.
It has 4 ports total. 3 on the side and one coming out the top. The one coming out the top is the the
only one that has a vacuum line going to it. And it goes to my carb. The 3 on the side were uncapped. I have since
capped them off. I ordered the chassis service manual today, so I can figure out what I am doing.
Transmission Controlled Spark. It prevents distributor vacuum advance until transmission is in high gear, which is the electric part of the switch. Early emissions device and commonly bypassed.
The way yours is bypassed you have no vacuum advance at all, meaning cruise performance and gas mileage are suffering.
CSM will explain it. Your choice to keep or bypass it.
I have a vacuum line that is coming off the manifold T, between the carburetor and distributor that is hooked to my vacuum advance.
Will that not give me vacuum advance?
I have a vacuum line that is coming off the manifold T, between the carburetor and distributor that is hooked to my vacuum advance.
Will that not give me vacuum advance?
Yes, that will provide manifold vacuum advance to the distributor.
The connection to the TCS is likely creating a vacuum leak, so as said, remove the hose from the carb to the TCS and cap the port on the carb.
Thanks for the links Joe. I'm going to disconnect my TCS from the carb and cap it off
And see how things work with using manifold pressure for my vac. advance
