whitehooptie

I've got a 94Z that I've had for about 17 years. It's always been the play car. I haven't driven the car very much the past few years as I've moved on to the Corvette world.

But saying that, I've been driving the hell out of this car again. I forgot how forgiving it can be and how much fun I had in it.

Driving it though has brought back some problems that I have ignored and swept under the rug. The biggest one I have is lack of vacuum. The power brakes are horrible and I cannot drive the car in 6th gear with the front vents on. After about 30 seconds to a minute, it moves to the defrost vent and the floor.

I was wondering if I bought a small 12v adapter to apply vacuum to the brake booster and the AC, if it would work. Any thoughts or is there something else that people do to make everything work.

And yes, it has a really big cam in it.

shoebox

Probably a leak in the system.

Injuneer

If it turns out to be the low vacuum pulled by the cam, the first approach would be a larger vacuum reservoir tank. If that doesn't solve it, there are electric vacuum pumps specifically for braking systems, use in some late model GM trucks. The Corvette LT5 engine had a vacuum pump, but not sure what the capacity is.

ZZ

You ever consider a hydro boost system from a 3/4 ton Silverado? Eliminates the vacuum booster and uses the steering pump. A lot more assist too. I don't even know if it will fit, but it could be worth investigating.

whitehooptie

WHere is the existing reservoir tank? Is it the one on the passenger side bottom rail at the front?

whitehooptie

It isn't a leak. I've had that car apart so many times it's sad. Fuel pressure on the stock regulator never drops below 40psi. The cam is somewhere around a 244@.050 on a 111 lsa. When I put the motor in, I just wanted a cam in it again. It's one I pulled off the shelf at a regrind shop. Who knows if those are the actual specs. Cam and headers, it lays down about 375 to the ground. Not too shabby.

Injuneer

Yes. Shoebox's link has info, and links to photos of the components.

A common problem is a broken check valve for the HVAC, and he describes that as well. But I suspect your main problem is the cam. I remember people trying to use the LT1 AIR pump for a vacuum pump, but I have no idea if it could generate the level of vacuum and volume of air handling required.

shoebox

Are you just saying that or did you actually test and prove it? Yeah, your cam might not be helping matters, but a leak in the HVAC vacuum system won't help, either.

whitehooptie

I currently have the entire dash out and will be pulling all of the HVAC equipment out to find any problems. The car is 21 years old and has been through a lot. I've had it since 98 and it was my learner car so I am sure there are some other issues that need to be addressed.

On a side note, it's good to see that you two are still on this site. I've been here for about 15 years and you guys have ALWAYS been hopeful. Hopefully everyone here still appreciates it as much as I do.

Fatdog2

whitehooptie

What are the chances of the vacuum reservoir going bad? All vacuum lines appear to be fine.

shoebox

Anything is possible. Doing tests will tell you. Lines cannot be judged good by appearance.

Injuneer

What was the result of this? Did you check the HVAC vacuum check valve?

whitehooptie

The entire dash is still pulled out. From the vacuum connector with the different colored lines, all is well. I'll be digging into the engine side of it in the next day or so.

whitehooptie

And the Check valve seems to be fine. Using the suck method and a finger or two (heh heh), there aren't any leaks.