The 1968 Ignition Switch problem

35-709 · March 20, 2018, 11:22:26 AM

Ahhh, wait a minute. A picture is worth a thousand words.

At the bottom center of the picture you posted is a "dashpot", that is called a "Vacuum Break Unit". You will see that it has a nipple on it that is supposed to have a vacuum hose connected to it and it just so happens that the vacuum source for that unit runs right by the nipple for the hose. There should be a "T" in that hose (the factory hose actually had a "T" molded in) with another vacuum hose going from one leg of that "T" to the Vacuum Break. Cut that hose (the lower one) put a plastic vacuum "T" in it (available at any parts store, get the right size), and run a short hose to the nipple on that Vacuum Break from the "T".

Write and let us know what happens when you test run it.

35-709 · March 20, 2018, 11:41:56 AM

This is a picture from my car of the Vacuum Break with the vacuum hose connected . I do not have a "T" because my system has been modified and the other items that vacuum hose went to have been eliminated. But you DO need that vacuum hose to the v. break.

35-709 · March 20, 2018, 11:56:51 AM

There is also another adjustment that controls just when the rear secondaries open when you step on it and that is the "Air Valve Spring Wind-up Adjustment". If it is improperly set you will get either a too rich mixture and black smoke from the exhaust and the engine will bog down because a lot of fuel is being introduced but not enough air. OR ,on the other side of the coin, you will get a bad stumble and hesitation because you are not getting enough fuel to handle all the air that the secondaries are introducing to the engine. This is usually set at the factory and never touched again until, possibly but not necessarily, the carburetor is overhauled.

This is NOT an adjustment to be made by your local repair shop hack, most aren't even aware of it. The proper setting for that adjustment is in the Cadillac Shop Manual. FWIW, the settings for the RWD cars are slightly different from the Eldorado.

metalblessing · March 20, 2018, 01:18:43 PM

Quote from: 35-709 on March 20, 2018, 11:22:26 AM
Ahhh, wait a minute. A picture is worth a thousand words.

At the bottom center of the picture you posted is a "dashpot", that is called a "Vacuum Break Unit". You will see that it has a nipple on it that is supposed to have a vacuum hose connected to it and it just so happens that the vacuum source for that unit runs right by the nipple for the hose. There should be a "T" in that hose (the factory hose actually had a "T" molded in) with another vacuum hose going from one leg of that "T" to the Vacuum Break. Cut that hose (the lower one) put a plastic vacuum "T" in it (available at any parts store, get the right size), and run a short hose to the nipple on that Vacuum Break from the "T".

Write and let us know what happens when you test run it.

Thank you very much, I just went and got a set of assorted Vacuum Tees, and a free 4 inch cut of vacuum hose (guessed on size, but it was free, so i can get another once I get out there and check). I am going to try this tonight after work. Glad we have 1 more hour of daylight now

35-709 · March 20, 2018, 01:28:29 PM

Don't forget to get rid of that tie-wrap around the linkage.

metalblessing · March 20, 2018, 02:10:46 PM

Quote from: 35-709 on March 20, 2018, 01:28:29 PM
Don't forget to get rid of that tie-wrap around the linkage.

Oh already done. I removed it immediately after I drove it yesterday.

metalblessing · March 21, 2018, 09:39:26 AM

Turns out that right-most hose wasnt connected to anything. Looks like the shop that did this just wedged it down there to get it out of the way instead of connecting it. Sadly it had no effect on the cars performance.

BUT I was thinking again last night and I was reminded of how last time I refueled with 91 octane, real gas it ran perfect for the day, then when I parked it for a week it was running like a turd again. If it ran good only when I refueled then maybe the fuel is mixing with existing water or bad ethanol and working good until it separates again after sitting.

I feel that if its running great after a refuel I should put draining the tank higher on my list. Maybe I can buy several gas canisters and a pump this weekend

35-709 · March 21, 2018, 10:01:05 AM

If you connected the short piece you fabricated from the "T" to the vacuum break --- good. If the other end is not connected to anything, it should be or you will have a good sized vacuum leak there and the vacuum break will not work. Make sure the other end of that hose is plugged off. You really need a mechanic or shop familiar with your vintage of Cadillac!!

Edit: Or at the very least get the '68 Cadillac Shop Manual (eBay) and give it to a mechanic willing to learn about the idiosyncrasies of a '68 Cadillac --- these are NOT Chevrolets!

35-709 · March 21, 2018, 10:11:59 AM

Just to be sure --- you have two hoses there in your picture, the one you want is the one connected at the carburetor, it is the lower of the 2 hoses that I see and is to the left of the other hose. Don't know what that other hose is but there should be another hose going from a larger fitting at the front of the carb to your PCV valve, maybe that is it. ALL vacuum hoses should have a destination or should at least be plugged off. Make sure none of them are leaking, a vacuum leak is one of the things that could be causing your problem and that vacuum break needs to be working.

metalblessing · March 21, 2018, 10:17:31 AM

Quote from: 35-709 on March 21, 2018, 10:11:59 AM
Just to be sure --- you have two hoses there in your picture, the one you want is the one connected at the carburetor, it is the lower of the 2 hoses that I see and is to the left of the other hose. Don't know what that other hose is but there should be another hose going from a larger fitting at the front of the carb to your PCV valve, maybe that is it. ALL vacuum hoses should have a destination or should at least be plugged off. Make sure none of them are leaking, a vacuum leak is one of the things that could be causing your problem and that vacuum break needs to be working.

Yeah that other hose turned out to just be sitting there. I didnt need to add a T because after closer inspection there was already a T in place. That hose on the right was connected to the T but the other end was just tucked down there out of sight, not connected to anything. I plugged that into the break. So there are no open hoses now.

35-709 · March 21, 2018, 10:22:36 AM

Please post another picture of what is plugged into what there.

35-709 · March 21, 2018, 10:25:03 AM

How about one of you guys with a '68 posting a picture of how those hoses are routed and connected in that area. I can talk all day about a '73 but if there are any differences between that and a '68 I have no reference available.

Highwayman68 · March 21, 2018, 10:29:02 AM

Blake do you have the Shop manual? If so look at page 6-55, there is a picture of the hose with the T in it, you can see how it is to be connected. If not I can do a scan shot and post it here.

Highwayman68 · March 21, 2018, 10:35:22 AM

Quote from: 35-709 on March 21, 2018, 10:25:03 AM
How about one of you guys with a '68 posting a picture of how those hoses are routed and connected in that area. I can talk all day about a '73 but if there are any differences between that and a '68 I have no reference available.

Unfortunately I am in a different city than my car at this time and will be for a while. Otherwise I would be sending pictures to help as pictures tell much more than I can type. I am only going by memory of the many hours I have spent under my hood. But I am always willing to help with what knowledge and experience I have.

Highwayman68 · March 21, 2018, 10:44:54 AM

Here is what the factory T piece looks like and how it is to be connected.

Please post a picture of your carb from the side and the top showing the vacuum hoses as well as the other vacuum hoses in the engine compartment so we can analyze what you have. As you have seen a lot comes from what we see in pictures.

35-709 · March 21, 2018, 10:54:51 AM

Thank you, Mark. Blake did post a picture back in Reply #38 of this thread. I am not sure of what that "other" hose is that is tucked down next to the hose we are talking about, or where it should go. And if there is a vacuum leak because it is, as Blake said, not connected and just tucked down in there. Also need to be sure he got the correct hose connected the the v. break.

35-709 · March 21, 2018, 11:00:18 AM

If that stray, disconnected hose should go to the PCV port then he's got a heck of a vacuum leak.

metalblessing · March 21, 2018, 11:49:45 AM

I am at work and dont have access to the car to take pics but I will take some tonight. I did take ONE pic last night before connecting the hose, if it helps here is a picture showing the disconnected hose that I plugged into the vacuum break. There were several T's down there, and the hose I connected was yet another hose that was connected to one of the T's and hanging loose.

35-709 · March 21, 2018, 12:27:45 PM

OK, that hose should be connected to the v.break and then the bottom leg of the T goes on to other places. Important that any vacuum hoses or Ts that are disconnected be connected or plugged and also important that none of the hoses are leaking and that they fit snugly onto whatever they are connected to. You want zero vacuum leaks.

Highwayman68 · March 21, 2018, 04:15:09 PM

Yeah, look at the picture I provided then look at your picture. Your picture shows the vacuum hose going past the dashpot when it is supposed to be T'ing in the dashpot. Also as pointed out the vacuum hose in your picture shows the hose is splitting causing a vacuum leak.

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The 1968 Ignition Switch problem