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[GMCnet] Vacuum after FiTech installation [message #303894] Wed, 20 July 2016 20:05 Go to previous message
Advanced Concept Ener is currently offline  Advanced Concept Ener   United States
Messages: 112
Registered: December 2014
Karma:
Senior Member
After installing FiTech FI system on my 455 the intake manifold vacuum has dropped from 22" at idle to 17.7". I have looked all over for leaks but found none. Idles smooth, runs great, mileage seems better than with carb but haven't driven far enough to verify. Vacuum at all loads seems lower by at least 3". Have stock intake manifold. What vacuum are others getting with stock manifold? This is new engine and trans, 3:46 gears, all new vacuum hoses, new brake booster, new electric vacuum pump on brake booster. Tried squeezing off vacuum lines one at a time to see if it affects manifold vacuum but nothing. Torqued down on TB again ( with all those spacer gaskets) but no difference. I did find a bad booster check valve but replaced it and picked up 1" to get to 17.7".

Jon Darcy ACES
North Jersey 76 stretch, flares, 4 bag, Alcoa's, bunkhouse,MAC Dash,Manny Trans, FiTech FI,Honda 6010

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