idiot-stick

I got this neighbor with an 81 Corvette. It runs like *** and I gave it a look and the vacuum advance wasnt hooked up. I hooked up a vac pump and pulled some vacuum and it ran a lot better.

He brought it back to his mechanic and he said its not supposed to be hooked up? It's an upgraded dizzy looks like, Accel I think but there's no brain box or anything to go with it.

Is the mechanic full of ---- or do I have no idea what I'm talking about?

fork

A vacuum advance does just that it advances the timing when it gets vacuum. There is no reason not to hook it up. usually there is a setscrew inside the tube that the vacuum lines goes onto to limit the amount of advance it can make from vacuum. if you hooked a vacuum pump up to it and it ran better then that means the car ran better with more timing. So number 1 advance the base timing. number 2 hook up the vacuum advance to the correct vacuum I always confuse the names but its the one with little vacuum at idle and a lot of vacuum under accel.

Tom-Guy

Common sense FTW!

Running locked timing generally sucks to drive, only ghetto turbo/carb guys do that.

idiot-stick

Thanks. That's what I've been thinking. I could be wrong about the distributor being upgraded. At least the cap is upgraded and I guess it's got a coil built into the cap or some ----. Next time we're fudging with the car I'm gonna try hooking it up and resetting the timing.

Tom-Guy

If the car runs like ***, the mechanic doesn't know what he's doing. Corvette owners like to spend money almost as much as Supra guys, even on an old affordable C3.

Smith-02

set base timing (4º) btdc. connect vac advance.

either that or time it 4 btdc with vac i dont remember. make sure to plug the line if its not connected.

fork

you need more than 4 degrees initial timing