Replacing '60 vacuum advance

[David Greenburg]

Can the vacuum advance unit on a '60 (with tri-power in case that makes a difference) be replaced in the car, or does the distributor need to come out?  FSM assumes its out of the car, but its not clear if that is necessary.

[James Landi]

I have a suggestion... although I've never tackled an engine with the additional carburetors, I've successfully replaced many advances... The entire process is so much easier with a specialize "double slotted" screw driver that grips those tiny screws...  here's a link to one such tool. https://www.jensentools.com/techni-pro-758sc301-1253-screwdriver-kedman-1253/p/758sc301    Hope this helps,  James

[signart]

Any work on a rear mounted distributor is easier and probably better on the bench (unless you are seventeen).    If you are not comfortable with the reinstallation, scribe a mark on the base of the distributor and the intake. It will rotate as you remove it and as long as you don't turn the engine, you can drop it back in the exact location.

[Lexi]

The tip James provided is a good one. Attached are a couple of images of the old school version of this tool. They work quite well. Clay/Lexi

[fishnjim]

Yes, it can be replaced in the car, but you have to take some of the distributor apart, and likes been mentioned, unless your a contorsionist and can work on top of the motor without damaging yourself, the car, or loosing one of those wee screws, it's better to pull it/bench it.
     
I assume you've tested the advance unit and it fails the vacuum hold test.   I'm not sure if that one can be repaired or not.   It's just a diaphragm that goes bad and the slide lever is attached to it.

It won't make much difference, if tri-power or not, provided you get the same advance unit.   The degreeing happens in the distributor.   
I'm running tripower on a 4 bbl distributor.   So what if I miss a few HP?   

[Roger Zimmermann]

Terrill Machine can overhaul the vacuum advance canisters.

[David Greenburg]

I will admit to being a bit gun-shy about pulling the dizzy if I don't have to. Never done it on one of these, and I've heard some stories. . .  While I'm not a contortionist and I'm a long way past 17, I do have a technique for working back there for tune-ups, wiper motor issues and such.  I use a step stool and a couple of old throw pillows and just do a belly flop on top of the engine. Looks a bit odd but it's effective. 

The old unit failed the vacuum test; it won't hold anything. It had not occurred to me to get it rebuilt, and I'm not even sure it is the correct part; it has a hose nipple cast into it instead of the fitting for a metal line. I was able to find a tri-power specific NORS replacement that is on its way. As for the "gripper" screwdriver, that would be nice to have. In the past I've sometimes improvised by using a small dab of strip caulk.

[Lexi]

Exactly, as David reported. Just got to make yourself more or less comfortable, but may very well be an issue if you are into 7 or 8 decades of old age (or engine still hot). Magnetic screwdrivers can also work, but they are also more prone to mishaps. Those Upson old school grabbers usually work really well. Think I have also seen them in Phillips format as well, but the old slots seem to be more common. Good luck. Clay/Lexi

[signart]

Do what your comfortable doing, but don't let the r/r dizzy intimidate you.  Just something to think about... you really should learn how to do if you own a car such as this, should you have to someday.

Forgot to mention, should you decide to remove the distributor besides marking the position of the base relative to the intake. Remove the cap and take note of the rotor button position, or just rotate engine till the button points toward the No. 1 cylinder.
Doh! prolly just talked you out of it!
Something else handy to know though.

[Moody]

I use a locking flat screwdriver. It's an updated version of the one shown above and works well. Matco Tools used to sell them. I'm sure they are available other places.
Getting in there is the hard part.
Dave

[David Greenburg]

After looking more closely at the FSM, it does seem pretty straightforward; the book recommends bumping the starter to get the rotor pointing to the rear.  And there's also that handy little camera that everyone has in their pocket these days that didn't exist back when the  stories I heard from fellow back yard warriors were occurring, making it less likely that I would need to spend an entire afternoon getting the car running again. A picture can be worth hours as well as words.

[James Landi]

I don't want to start an argument among you fine gentlemen, and since the point I wish to make is not fact, but simply a personal observation, please do engage in the discussion, I'm always willing to learn from others, who are likely more experienced.  I've owned two 56 Cadillacs,  and a bunch of others that sported vacuum advances.  While these big block engines run very nicely with a broken vacuum advance, I always felt (feel) that replacing a broken one was well worth the effort... with some of these, the gas mileage increased... with the late 60's early 70's, the engine "response" at moderate take off, say at a traffic light, seemed much more crisp and responsive.  In the early 8 litre models that had the speed sensitive vacuum advance cut out, I simply bypassed that device, and found the engine response at acceleration markedly better.   So all this is to say that I enthusiastically vote for checking out those advances, and change out the broken ones---  (it's certainly far easier when the distributor moved to the front!)    Happy day,  James

[David Greenburg]

I must admit that my car is running pretty well even with the broken advance and resulting small vacuum leak;  the only obvious symptom was a slight stumble on hard acceleration, and the main thing that prompted me to check the advance was getting ready to tweak the timing to enjoy the current tank of mostly 110 octane that was the subject of another thread.   

[CadillacFanBob]

Lexi,

Do you have tool number for that screw driver, usually had a tool number on handle?

Thank you in advance,

Bob