Additional air valve/do I need it?

[gumba]

I'm making a list of a few parts I'm short. Do I need this part, #52 additional air valve
930 110 275 01(pet '78-'83 turbo). This is going on a '79 3.3 cis motor.
thanks.

[gumba]

Here's a shot of the part.

[gumba]

On the '77 pet, it doesn't show it, so maybe not?. This is a 3.3 bottom end with 3.0 heads & cis.

[jwasbury]

Its yet another cold start/throttle bypass device and you don't need it.

[boosted79]

You can live without it but you'll need to give it some throttle for warm starting. It bypasses air around the closed throttle plate for startup but then closes with decreasing manifold vacuum when the throttle plate is opened. The early CIS cars didn't even have it, they had a hand throttle, aka shade tree cruise control. The AAR does the same thing but is temp controlled and aids in cold starting. It's closed on a warm engine. One side benefit of no AAV may be flames on decel with a zork

[gumba]

Thanks.
(One side benefit of no AAV may be flames on decel with a zork) Now your talking!

[RarlyL8]

#52 is an extra bypass valve found on some of the earlier 930 engines. The decel valve on all CIS 930 engines is not shown in your diagram. You won't notice it if missing as there are many other valves kicking up the idle during various conditions.

[gumba]

There won't be any other valves on this motor except the aux. air regulator. My '79 3.5 just has the aux air regulator and the #52 air valve.
The '79 fires right up but I need to give it some throttle to keet it going until it warms up.

[JFairman]

#52 is a "deceleration valve" and it bypasses metered air around the throttle body when it is opened by high intake manifold vacuum during closed throttle deceleration. It's exactly the same as not taking your foot all the way off the gas pedal while decelerating.

Deceleration with the throttle closed all the way increases nitrogen dioxide emissions out the tail pipe. The purpose of that valve is to reduce those emissions.
The engine will decelerate a little faster between gear shifts when you take your foot all the way off the gas if you remove it or if you remove the small vacuum line that operates it... even with the 10 ton stock clutch pressure plate on the flywheel.

If you drive and shift slowly like an old lady maybe you would prefer it in place because engine rpms will match up better when you slowly select the next gear. If you like to shift a little faster and at the upper limit of the old style steel Porsche synchro action and you don't need it to pass emission testing you will probably like driving the car more without it.
Or you can leave it in place and remove the skinny vacuum line on it and it will never open even though it's still there.

[gumba]

Thanks. I don't have one, and at $195.00 I'd prefer not to buy it if I don't need it.

[Speedy Squirrel]

Oh no! Fairman has gone wild again! It has nothing to do with NOx. It adds some air at closed throttle so that the fuel will burn in the cylinder, rather than making the farting sound in the exhaust. Some find this flatulence delightful, like that scene in Blazing Saddles, others not so much

[gumba]

Well, if the folks behind me don't like the farting sound I will give them the option of buying me the valve.