Chevy Tri Five Forum banner
1 - 6 of 6 Posts

·
Premium Member
1957 Chevy Bel Air Convertible; ZZ4 w HEI ign; 700r4; 9" rear w/3:50 gears; pwr disc fr w drum rear
Joined
·
1,971 Posts
Discussion Starter · #1 ·
Calling all Southern Air AC System owners.....I have a question.

I have an older Southern Air AC system with vacuum activated doors to direct air..........

The system has a vacuum canister, and I am unfamiliar with how these work, but I'm assuming it holds a reserve of vacuum for when the car isn't generating required vacuum level.....?

Does this mean I should be able to connect my vacuum canister to "ported" vacuum? (since it holds a reserve) I moved it from manifold vac to ported recently, but I'm hearing some ticking at evaporator case now when my ported vacuum closes at idle or even coasting. So, I'm wondering if the canister is just old and needs to be replaced...or if I need to move it back to manifold vac.

Thanks

Ace
 

·
Registered
Joined
·
37,246 Posts
It probably doesn't really matter much, since you want to pull the most vacuum in the can as possible. This is going to occur when you're cruising at a speed above idle, or when decelerating.

But, to be sure, connecting the can to "manifold vacuum", as opposed to "ported vacuum" will give you more vacuum to the can at idle. Since the can should have a check valve on the source, it's just going to keep the highest vacuum it sees anyway, per the above explanation.
 

·
Premium Member
Joined
·
14,044 Posts
you should connect to unported direct manifold vaccuum . also use a check valve between th canister and the manifold source.
 

·
Premium Member
1957 Chevy Bel Air Convertible; ZZ4 w HEI ign; 700r4; 9" rear w/3:50 gears; pwr disc fr w drum rear
Joined
·
1,971 Posts
Discussion Starter · #4 ·
hotrodg, if there is a check valve, why would it need to be manifold vac? Ported provides just as much vac once throttle is opened, and wouldn't even occasional throttle provide enough to restore vac in canister?



Ace
 

·
Premium Member
Joined
·
14,044 Posts
the check valve helps a lot when at wide open throttle or agressive acceleration. The vaccuum will bleed of rapidly in the canister in low vac situation the check valve eliminates this. As far as source to me it is a matter of preferance as to how effective the system is . With ported source you may not have vaccuum right away when starting the car after it has set a few days. with mainfold vac you have it immediatly and can get you system adjusted to comfort before you ever touch the throtle. Take a good look at most stock vac operated systems, the usually use manifold vac . If it is good for the general then it is good to me. Just my opinion.
 

·
Premium Member
1957 Chevy Bel Air Convertible; ZZ4 w HEI ign; 700r4; 9" rear w/3:50 gears; pwr disc fr w drum rear
Joined
·
1,971 Posts
Discussion Starter · #6 ·
Thanks hotrodg, great explanation.

I currently only have one manifold vac inlet on the front of my carb, so I'm wondering how many components is practical to run off of that one line. I already have my distributor advance and vacuum switch for lock-up running off that line....so I didn't want to add another.

Do you think having too many components running off of a single line could affect the performance of those compnents individually?

Ace
 
1 - 6 of 6 Posts
Top