matchek

Where.does the vacuum hose go from the heat riser valve (on the edge of the air cleaner)? Carberetor? Manifold? Right now the valve is always open due to no vacuum hose on it.

Octania

Manifold vacuum via the temp sensor in the base of the air cleaner.

matchek

Thank you. Where do I connect the vacuum hose to get the vacuum needed to close the valve when the engine is cold?

QUOTE=Octania;442325]Manifold vacuum via the temp sensor in the base of the air cleaner.[/QUOTE]

brown7373

You didn't say what year, model or engine you have, but my 1972 Cutlass 350 has a nipple on the back of the 4 bbl intake that connects to the air cleaner. The nipple is a screw-in plug, 3/8 maybe that screws into the intake, that narroes to a small diameter nipple sticking straight up that the hose attaches to.

MDchanic

Just about anywhere, as long as it's manifold vacuum.

For the perfect restoration, sometimes it was a barb on the manifold, sometimes on the carb.

It might help if you told us something about what kind of car you have.

If you live in NC, then the whole question os moot anyway, because it will never get cold enough for you to notice an difference in operation with the valve connected or disconnected.

- Eric

rocketraider

If you're asking about the ThermAC flap in the aircleaner snorkel: vacuum hose runs from its vacuum motor to a thermostat located under the bottom of the aircleaner near the carb opening. There are two vacuum nipples on this thermostat. Hose runs from one nipple to the ThermAC flap motor, the other nipple's hose runs to a fitting on intake manifold behind the carb. This intake fitting has a very tiny hole in it, not much bigger than a pinhole.

ThermAC is an emissions control device designed to lower cold start emissions by preheating intake air for quicker warmup and less time on choke. On a cold engine start, the thermostat senses cold air coming into the aircleaner and closes off the ThermAC's flap to switch intake air to preheated air. You'll see a tube running from aircleaner snorkel to a heat stove on the exhaust manifold. As the engine warms up, the thermostat will bleed vacuum and move the ThermAC's flap to open the snorkel to cooler outside air. On moderately cooler days, the thing will modulate to maintain a warmer intake temperature.

When your car was built, a lot of them got "de-smogged" soon after purchase. That generally meant disconnecting or plugging every vacuum hose on the engine and a lot of times was done by a service station mechanic who was not familiar enough with the car to know what all the vacuum lines were for. Predictably, a lot of early smog-controlled cars ran poorly.

A 1968 Chassis Manual will show how everything is supposed to connect. Though in all honesty, a stuck-open ThermAC is not going to hurt anything. One that is stuck closed is worse.

matchek

68 Delmont 88. 455, 2bbl.

Probably is moot but I would like to connect

Still seeing where to run vac hose from snorkel. Dont see any obvious nipples on the carb. On nipple on the manifold near the distributor was capped.

Appreciate the responses.

MDchanic

RocketRaider seems to have discovered that you have a 1968 Delta.

In that case, consult page 6N-1 in your Chassis Service manual for operational details of the Controlled Combustion System.

As far as I can tell, there is no vacuum hose routing illustration in the '68 CSM, but this is what the 1970 manual shows:



The hose should be connected to one of these barbs, probably the one on the passenger side, if it is present.



- Eric

matchek

Thanks Eric.Nice pic.

The passenger side barb has a hose that goea to a tee.

Somebody put a rubber tee on the drivers side barb you circled. It must be that one! Thanks.

MDchanic

If my memory is correct, there are five potential things connected to vacuum on the '68 full size:

1. Power Brake Booster (steel tube that screws into manifold and goes over to booster)
2. Automatic Transmission Modulator
3. Air Cleaner PreHeat Valve
4. Air Conditioning Controls
5. Distributor Vacuum Advance

The first four supplies are functionally identical (except that the brake booster lines are larger), and it makes no practical difference where you connect them.

The distributor may have been connected to manifold vacuum, but I believe it was connected to ported vacuum, on the carburetor.
I don't believe there was any temperature controlled advance on these, except maybe for California.

That leaves three hose barbs on the manifold (excluding the big brake booster tube): A/C, Transmission, and Air Cleaner.

As I said, they are functionally identical, and you can connect any hose to any barb.

If there are plugs and Tees, that means that someone probably rerouted the vacuum advance from ported to manifold vacuum, or disconnected something that shouldn't have been disconnected. In '68, it was one hose to one barb - if a barb wasn't needed, a plug was installed at the factory instead of the barb.

- Eric

matchek

Hooked up. Snorkel valve working great.

Everything working great. Lights go on bright and power windows move faster like it should.

For some reason the generator light comes on now. Not sure if a coincidence or not.

matchek

Is there something I could have bumped to cause the generator light to go on?

Put a/c , lights and power windows and it seems fine.

MDchanic

Alternator terminals?

Regulator terminals on firewall?

Check your charging voltage - if it's too high, you'l start blowing bulbs.

- Eric

matchek

Funny thing is gen light went out now
Maybe it fixed itself. Lol

Battery measures 13.2 V
W engine on 15.4 v
With light and engine. 14.2
With engine, lights, and AC 12.8 v

matchek

Correction: someone put a rubber cap on the drivers side barb.

MDchanic

15½ volts is a bit high.
Enough to cook the water out of your battery on a hot day.

Seems to me you need a regulator.

- Eric

matchek

Thanks
What is ideal? It isb12.8 w the ac and lights. That seems alright.

MDchanic

Somewhere between 13.5V and 14.5V is generally okay.

I have a reference somewhere giving precise numbers for every type of battery out there, but essentially, old-style lead-acid batteries, which are only used in 100-point restorations these days, are near the lower end, lead-antimony "maintenance-free" batteries, which are the type we all use, are about 14.5, and adsorbed-matrix batteries, like the Optima, are a wee bit higher.

Your alternator is pushing 15.4 volts. You need to correct that.

Afterward, you need to figure out why it's only 12.8 volts with the lights and A/C on.
(Was that 12.8 volts at idle, or a bit above? - it's normal behavior for an period alternator at idle).

- Eric

matchek

Thanks Eric. It was at idle.

MDchanic

I wouldn't worry about it, then. Recheck it at about 1200 RPM to be sure you can still charge while running all the accessories.

- Eric

BILL DEMMER

it also matters what temp the regulator is at when you check it. when it's cold, it will be at a higher voltage, say 14.6, as it gets to N.O.T. it should go down to ~13.8-14.2. there is a chart in the CSM for this.


bill