I installed a y8 on a z6 and im getting a major vacume leak. I spayed carb clean along the top of the manifold where it hooks to the block and and the carb cleaner is going into the motor. It's has some major hissing coming the head/mani. I instaled a brand new honda y gasket, I just dont see how I'm getting such a bad leak, the bolts where tightend in the right order and are tight as hell. I am going to try and put a bobo gasket that I bought at a local autoparts store and see if that fixes it. Should I have bought the gasket the match the head instead of the manifold, could the mani need to be resurfaceD? It's off a 2000 so I dont think it warped or nothing. Any help would be apreciated. Thanks

 

did you mess with the throttle body or any of the injectors/sensors?

 

I just swap in my odb0 injectors, an a b series tb. I tried both gaskets now and both leak. Every thing work out fine when I put the a6 manifold with a new honda gasket on it, but now y8 is giving me problems that pretty much narrows it down the the new intake manifold. Should I have it milled?

 

they the nuts are supposed to be tightened to 16ft/lbs i believe. maybe you over tightened it and warpped it. just a suggestion

 

listen up because i have been here before and i know what i am talking about.
the Y8 manifold that you are having the problem with is most likely from a 99 or 2000 civic ex....these manifolds were different from 96-98 because honda changed them to add in an air assist feature for the injectorswhich worked on cold start up. the manifold and cylinder head were changed to provide an air passage which is routed to the injector....if you were using the cylinder head and intake gasket then you would not have a problem BUT there is a solution.
remove the manifold (yes you really have to) ...now look at the flange where the intake gasket goes...right above the main intake ports you will see a small hole just above each runner....this is your vacuum leak. i plugged mine using JB weld (greatest stuff ever invented) you need to make sure that whatever you plug the little holes with doesn't stick out from the hole...if it isn't flush then the intake maniflod gasket won't seal. hope that this helps

 

very good advice from the guru or canabalizing also labled as Hybriding

listen to this guy sounds like he knows his junk

 

i just did this, so i will add one thing..
the little air assist holes that you will be plugging are smooth on the inside.. so i ran a sheet metal screw into them just to rough up the surface so the jb-weld would have something to "grab" onto.

that massive vacuum leak sucked too, i had massvie pinging and my engine was loud as ****.. now my timing is set to 18° and it is quiet like a happy new honda

 

Thanks for the help, that would be the problem then because I do have the 4 little holes. I'm just fill them in then lightley block it flat. Thanks for the help.

 

I had the same problem before when i got my Y8 mani and yes it has the tube thingy and 4 holes. I talked to the guy where i got my mani and he really help me out and send me the one i need wohoo. Here is the 2 pics of the mani.. Left is the one and the right is the right one lol..