[toddiyaayas]

I have an 81 camaro, 350, stock HEI without vacume advance, all emissions are removed with the exception of the PCV. Question: I have a 4" round cylinder ball by the firewall on the passengers side and it has a vacume line running to it from the carb, but has the outlet plugged. Can anyone tell me what this is? And what it is used for? Right now the outlet is plugged...should it be?

[StevenC]

vacuum canister probably.

[farna]

The ball is nothing but a vacuum storage container. Pull and plug the line at the carb (buy a vacuum cap) and remove the ball. Someone obvoiously didn't know what it was so just plugged the outlet and left it in place to be safe. These are used to store a bit of vacuum for the vac operated devices such as heater and AC controls or a crusie control. Vacuum goes down when you accelerate or are pulling a load. The stored vacuum maintains enough to operate the controls a few times or hold a cruise servo open when the engine isn't producing much vacuum. There are one way check valves either built into the ball or in-line in the tubes -- or there was originally.

If you know someone with an old rod or restored car with vacuum wipers give them the ball. It will help the wipers keep running for a short up hill pull or through a short acceleration period -- or at least runing faster than without it.

[toddiyaayas]

Thanks, I didn't think it was needed.

[MI2600]

Don't be too hasty. This may be part of the heater system. If removed, you may not be able to change heater functions.