Both gaskets? Well stock you have an o-ring. What some are doing is leaving the stock o-ring and putting the 90mm on and calling it a day. If you look into the 90mm, the stock o-ring basiclly is barely doing anything and the o-ring that comes on the arrington is not really grabbing onto anything because the openings are totally different. The stock o-ring is now inside the opening of the throttle body. When you mill/deck the intake manifold, you now have a perfectly flat surface that is the correct deminsions for the arringtion o-ring. No leaks since it is now setup in a manner that allows for a proper fit. You could make another gasket or use some silicone as an added source of sealing the area but from what I've seen, the arrington o-ring does its job when mated to a flat surface. My bet 8youM5, you have a vacuum leak and your car is fighting it.
I agree Dan about the mating surface being flush after machining. I actually removed the Arrington O-Ring and used silicone to ensure no vacuum leaks. I found when using the O-Rings they dont line up because the throttle body and manifold bore opening are not centered. Prior to any machining or making the opening bigger, I had a whistling sound and rough idle that went away when I stripped off both O-Rings and used silicone to seal it.
Yes they do!!!!! I looked at what you did......we followed similar paths. I machine bored mine down deeper but ended up with a bit more step at the roof. I also made a cardboard "tool" because of the misalignment between the throttle bore.
Ya, I was concerned about the o-ring at first but after double and triple checking, the 0-ring on my arrington is nicely centered and is holding up nicely. No doubt silicone would be a nice security blanket and if the needs arises, I'll be using it myself. Nice conversation here, hopefully others will learn from it.
