Fast 78 injector o rings
Thread Starter
Joined: Mar 2011
Posts: 1,194
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From: Southeast Missouri
Fast 78 injector o rings Hi everyone I recently put a fast 78 on and took off my ls1 intake. My car now sounds like it has a bad air leak. Do the fast 78 require the fast o rings for the ls1 style injectors like the other fast intakes do? I figure this may be my problem
I have always used stock GM orings on injectors even with the FAST 90mm.
Did you use new intake gaskets on the FAST? The 78mm hasn't been sold in a long time so they could be too old to seal. Also did you install the button head cap screws in the valley cover to replace the stock bolts?
If you replaced both of those things double check all your rubber hoses and look for unused open ports on the intake which might need to be capped.
If you are using an aftermarket throttle body it could be hiss from the IAC passage since they are typically smaller and sharper so they pull air faster and can make it whistle a little.
Did you use new intake gaskets on the FAST? The 78mm hasn't been sold in a long time so they could be too old to seal. Also did you install the button head cap screws in the valley cover to replace the stock bolts?
If you replaced both of those things double check all your rubber hoses and look for unused open ports on the intake which might need to be capped.
If you are using an aftermarket throttle body it could be hiss from the IAC passage since they are typically smaller and sharper so they pull air faster and can make it whistle a little.
