1970 Deville - 472/500 What temperature thermostat?

[Glen]

What is "ported" vacuum?   

Ported vacuum is connected to the front of the carb. With the throttle closed the vacuum advance gets no vacuum.  If the throttle opens just a little bit the vacuum advance gets full manifold vacuum and as the throttle opens more the vacuum decreases much like the manifold.  So at idle the spark is retarded. 

[TJ Hopland]

The inlets for the 'ported' or 'timed' vacuum connections are typically above the throttle blades when they are closed (idle).  The throttle blades are what is restricting the air flow into the engine and how the vacuum is created so when they are closed you got vacuum on the engine side of them and nothing significant on the other side till you open the throttle a bit.   Some carbs some of the connections are that simple but others they get much more complicated than that.   Sometimes part of the system is that the throttle blade actually blocks the vacuum port in certain positions.   Someone mentioned Fords distributors, in the 60's they had one that was called a Load O Mattic.   The carbs had a special passage with a control valve that looked like a Holley 'power valve' that created the wacky vacuum signal for the equally wacky distributor.   

[Jeff Rosansky CLC #28373]

OK, thanks guys.  I wasn't sure.
Scot, If you have that, please send it when you can.  Mite as well check to see all is where it should be.
Jeff

[TJ Hopland]

Talking about smog pumps in another thread reminded me that the diverter valve on the smog pumps is one thing that has an unusual funky vacuum connection.  The valve operates only under deceleration so it just gets a 'blip' as the throttle closes.  I can't remember if its a blip of vacuum or a blip without.  The point of mentioning this is that if you connected the distributor or egr or one of the vacuum brakes / pull offs to that port things would not work the way you expected them to.    Could also be a problem if you didn't have the correct carb and that port is or isn't there.  A lot of the emissions stuff had odd vacuum requirements and that stuff tended to change a little year to year and CA vs fed cars so you can run into all sorts of issues with connections and carbs especially if you are just guessing how to hook things up or assuming its all correct.   Sometimes you need to hook up a vac gauge and confirm what and when they are doing their thing.

[Scot Minesinger]

The last couple of Cadillacs that I worked on were brought in for symptoms characteristic of vacuum leaks.  In all cases the vacuum hose from carb to vacuum pump, when tested proved to be one of the leaks.  The vacuum connection to the air pump had a ruptured diaphragm.  They choose to not repair the air pump and so I plugged the vacuum line down to the air pump figuring it did not work anyway.  After the vacuum leak was stopped, the cars idled smoother and did not knock under heavy acceleration, but I had to re-time them though (who knows if they were timed correctly anyway, since it has to be done in drive).

[TJ Hopland]

Vacuum pump?  Or did you mean to say AIR / smog pump?

I can't remember in the air pumps if no vac signal makes em blow in the heads our up to the air cleaner.   No air does not seem to hurt things (other than emissions) in the 70's cars.  80's it seems to burn valves but that is more likely not a direct effect of the air system, likely a result of the computer not being happy and trying to fix things.    Air all the time makes a slightly annoying popping in the exhaust during deceleration.   

[cadillacmike68]

Didn't Cadillac use a 3 port "switch" (really not much more than a was bulb that expanded when hot) that opened and closed the ports  that in turn controlled where the distributor got its vacuum from?  My 1968 has one, and I'm pretty sure the 1970s have the same switch. Eldorados might have a 4 port one.

If that switch is working, as soon as operating temp is reaches, the distributor should get full manifold vacuum. No need to mess with the car's vacuum plumbing, just make sure that switch works and your vacuum break diaphragms are in good condition.

At least you don't have to deal with the AIR pump disaster (I don't either -    ).

[cadillacmike68]

This is similar to the thread I started with my 1968.  The 68 has a gauge, and it may be a case of over worrying on my part, but I do not want to damage the bearings by overheating.

Part of the reason for the gauge going away in 1969 was the addition of the turn signal indicators. The 68 and earlier cars did not have the green arrows in the dash, and they needed room for these things. So the gauge went away.

The "Engine Temp" light and buzzer is mentioned in the shop manual, but the threshold temp is not indicated.  It is good that this never activated.

Incorrect Timing is listed as a specific cause of overheating, so that should be checked.

The 7 bladed fan was only used on AC equipped Eldorados (& commercial chassis), not on all AC equipped cars.  That said it is a better fan, especially in today's world with stopped traffic.

The 1970 Cadillacs used a flexible blade fan, but of higher quality than the ones Scot referred to earlier.

Chris,

Was the block bored when rebuilt? That will cause it to run mildly hotter. 

If you do not live way up in the snow belt, you should use a 180 deg thermostat.

Where did you get your Flow Kooler water pump. I take it you were able to get the lower hose attached. Even if its very tight, it only needs to go on or off when the pump is changed, so it shouldn't be a serious concern.

The newest ACDelco pumps seem to have a similar if not identical impeller. I'm going to call the Flow Kool folks tomorrow and try to get some info out of them.

[chrisntam]

The block was bored .030 over.  Put a 500 crank in it.  I live in Dallas and bought the pump directly from Flow Kooler.  When I pull the oil pump, I'll re-situate the lower hose on the pump outlet a little better.  It's still a dang tight fit, when it doesn't have to be.

As a side note (I like side notes!), while driving my '75 Olds 88 yesterday (with a 195 stat in it), the mechanical water temp gauge reads about 200. while driving and no a/c on.  Outside temps are in the 90s.  When I shut the engine off and watch the gauge, it creeps up to 230 degrees.  To me, this means the water by the temp sender is absorbing the heat from the block, which indicates the block temp by the sender is 230 degrees. However, as soon as I start the engine, it goes back to about 200 pretty quickly.

With that said, my engine temp sender on the Cadillac (measures block temp, not water temp) may be correct and therefore, nothing to worry about.

Is my thinking flawed?

chris.

[Scot Minesinger]

Chris,

Same thing happens to me when the car has been running for a while during hot weather, may be 205'F when I shut off the car and go into the post office.  When I return after 15 minutes and switch ignition key to run, but do not start it, the temp gauge is powered and gives a reading of 230'F or so.  As soon as I start it within 15 seconds it is back to a reasonable temp.  I think you have nothing to worry about here.  Mine too was bored 0.030 over (makes it a 478 engine instead of 472), and I have heard as well that this makes it run a little hotter. 

This has ben happening for years (that I can verify with addition of gauge) and no issues.

[TJ Hopland]

I was out messing with my 73 this afternoon.  I have a fuel pressure issue causing some quirks that I am working through.  I went out for a quick test drive then came back to the drive way and did some tweaking on the computer so it was idling for a couple minutes.  Noticed the temp gauge reading around 220 (metal temp sensor on the inside water outlet bolt).   Pulled up the coolant sensor on the computer (mounted where the thermal vac switch was) and it was reading 203.   Popped the hood and grabbed the IR gun,  top rad hose reading 200.  Front of block 200.   Outside bolt of water outlet 202.  Inside bolt where sensor is located kinda hidden by the AC compressor 205.  I start scratching my head and go back and look at the gauge and the computer now they both say 200.    It must have been an under hood airflow issue making the area with the gauge sensor read high.   I have the OE 'water' light sensor still in place and that never came on so I know it never got hot.  I could also confirm that by looking at the logs in my EFI system but I forgot to download em. 

[cadillacmike68]

On the temp gets hotter while the engine is shut off phenomenon:

The owners manuals actually state this and I see it with my temp gauge. Get it hot, shut it off, come back in 15 min and look at the gauge and it will be at least 1/8 of the way hotter, sometimes 1/4 more. Get moving and its fine.

So you have a 506 CID now, eh Chris? You had to get different connecting rods as well, correct? That must put out some power.

I think we are both reading a little too much into all this, but I have an actual gauge that creeps up way too much for my liking. I'll have to "calibrate" it like someone mentioned using a temp gun

TJ; what, do you have some sort of computer hooked up to your 1973? what software are you using?

Different era, but my 96 Fleetwood lines it from 95-100C, it will shut off the fans at idle to keep the temp there.   out older cars, maybe 5-10deg F cooler, so 200-205 should be a good running range.

[TJ Hopland]

I have a kit built EFI system called Megasquirt.  Until this season its worked very well.  I think the problems started out with the fuel return line apparently partially plugging over the winter (or maybe slightly every winter and this year it was bad enough to notice).

[cadillacmike68]

TJ, I'm guessing you also put a temp gauge in your car. How did you hook it up and where is the gauge hiding?

[TJ Hopland]

I don't seem to have a picture handy of it in the car but here is where I got it. 


http://www.digi-panel.com/index.html

I got the 3 gauge version and its on the lower slanted part of the dash between the steering column and ash try.   I really like lit.  The metal temp sensor lets you keep the stock stuff in place.  I used a T for the oil pressure so I have both there too.   The led bars are a really good choice because in most cases as something changes it kinda blinks the next bar or bounces back and fourth so it tends to get your attention.   They are also colored so green is the happy range so that is another way at a quick glance you know if you have to look closer.   It appears to be a one man operation and he is kinda old school.   I called him to verify stock or lead time then mailed a check.   I would think he could build one with a connector on the back if you wanted to be able to easily remove it.

[cadillacmike68]

That's an interesting setup. I like how you can keep all your original indicators (I have a real temp gauge in the 68 that I want to keep).