What kind of vacuum is in a 1978 Corvette?

1978 Silver Anniversary L82 4spd (M21) Red Leather. Pace Car is in the hands of a new caretaker. Since I’m having similar problems with the heat and vent control lever in my ’80, I’m all ears on this one.

How to troubleshoot a vacuum in a Corvette Stingray?

Or you can do a step-by-step check by starting at the intake manifold and testing each component in the system beginning with the filter, then the check valve, then the headlight switch, etc. Notice that once you reach the check valve, there is another path for the vacuum where it goes to the reservoir for the operating subsystem.

Where is the vacuum reservoir on a vette 73-79?

NOTE: In 73-79 Vettes, the vacuum reservoir is incorporated into the front crossmember. The crossmember is a hollow tube which runs between the frame members with three vacuum fittings, one vacuum inlet on the driver’s side and two outlets near the center to provide vacuum to the headlight actuator relays.

Where do the vacuum lines connect to the check valve?

The problem with the vents could be a bad vacuum control valve that controls the air ducting, a bad actuator on a damper or something much more simple. Look under the hood and find where the vacuum lines connect to the CHECK VALVE . One of the two lines that connects to the check valve goes to a “T” .

Where does the heater line go in a corvette?

One side of that line goes through the firewall to the heater controls. Carefully check the “T” itself and the hose where it goes through the firewall, make sure it isnt broken or the ‘T’ isnt cracked. [QUOTE=mysticstriper]P.S.

Are there diagrams for the C3 vacuum system?

They should both have diagrams and info. on the C3 vacuum system. Glad to see you using this site. The more you use it, the better you’ll like it. At least that’s what I’ve found. Let us know how you do with the vacuum. 2nd. site should be correct now. Good lookin’ out, Dejablue! FirstCorvette!

Where are the vacuum lines on a corvette?

Sarge…just went through much of this in my 78 when I did a heater core replacement. I verified the operation of all systems, tested actuator doors, checked vacuum lines, tracing them all back to source. The previous contributor had it right…it’s the black line that plugs into the back of the A/C selector switch.

Why is the vacuum not working in my Corvette?

The end with the single port should not maintain vacuum pressure and you should not be able to blow air into this port. A leaking check valve may cause the headlamps to open when the engine is turned off; but this depends on the condition of the rest of the headlight vacuum system.

What does a vacuum test on a car mean?

Engine Vacuum Test. Steady low between 5-10 “hg vacuum: This indicates that the engine has a leak in the intake manifold or the intake gasket. This leak should be easy to find because it would be making a loud hissing noise. Steady low between 10-15 “hg vacuum: This reading indicates late valve timing.

What does steady low mean on engine vacuum test?

Steady low between 5-10 “hg vacuum: This indicates that the engine has a leak in the intake manifold or the intake gasket. This leak should be easy to find because it would be making a loud hissing noise. Steady low between 10-15 “hg vacuum: This reading indicates late valve timing.

Can a stock vacuum can work on a modified engine?

Manifold vacuum, so those cans don’t work very well on a modified engine; with less than 15” Hg. at a rough idle, the stock can will “dither” in and out in response to the rapidly-changing manifold vacuum, constantly varying the amount of vacuum advance, which creates an unstable idle.

Do you need a vacuum advance in a race car?

“Race cars” run at wide-open throttle, rich mixture, full load, and high rpm all the time, so they don’t need a system (vacuum advance) to deal with the full range of driving conditions encountered in street operation.

What kind of vacuum is in a 1978 Corvette?