Thread: Simplifying CIS
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silverlock silverlock is online now
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Join Date: Aug 2023
Location: New York City
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Quote:
Originally Posted by fanaudical View Post
The AAV is almost never the cause of a vac leak. Bad boots, hoses, injector seals and sleeves, and air boxes are almost always the cause of the vac leak. Intake runner boots are a maintenance item - you just replace them every so often (or you replace them when they fail and hunt for the reason why nothing runs right).
Agree here with the AAV (and the AAR). Both are simple devices — the AAV especially so — and most of the leaks just come from the hoses. That big 3-way hard line part that goes into the AAV and the back of the intake can be a source of small leaks over the year. The hoses fatigue. All of that is easily repairable.

If you're in California or Florida where it's rarely that cold you might be able to do without both, but anywhere else it'll be a bit of a pain (esp. w/o a hand throttle/choke to make up for it).

IMO: the decel valve can go. I'm OK with some overrun and never liked the way it held revs.
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1978 911 SC (3.2SS, EFI, 993SS cams + the trimmings)
Dynamic Comp Ratio calc: https://dcr.questionable.services/ • Gearset & Ratio calc: https://ratio.questionable.services/
Old 09-24-2025, 07:59 AM
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