OK. I just spent 3 days doing the valve cover gaskets and supercharger coupler. While the SC was off I replaced the intake manifold gasket because the old one fell apart. Put everything back together, 2 or 3 turnovers and it starts up. SUCCESS!!!!!!!

Or is it...here'* what'* happening now. (FYI The engine seems to be running great, not missing, and accelerates/revs up smoothly)

First issue: at idle when RPMs are under 1000 I get this sort of whining sound, maybe grinding sound it'* hard to tell. But right as I hear it the car starts to vibrate. Sound and vibration go away when I give a little gas. NOTE: I'm told main bearings are worn, but I've known that for a while now and it'* never made that sound. Any ideas?

Second AND MOST IMPORTANT issue: Now while driving, when the car upshifts or I take my foot off the gas the car jolts violently. Any ideas?? I'm thinking a sensor.

Observations: Takes a long time for rpms to settle below 1000 when I rev it, it seems to hover at 1200 for a while, then suddenly drops to 800 or so, then that sounds starts happening.

First, check for vacuum leaks. Then check over your motor and trans mounts.

Check your hose that connects to your transmission shift control module towards the front of the transmission. When I took off my SC the hose was cracked and needed to be replaced. Good luck and let us know.

Did you put a new gasket under your SC air vac block on your SC mine was bad and alot of vaccum pressure was leaking here at this part. I used GM gasket maker to make a new gasket to seal up the leaks. Well I hope this helps out.

Hmmmm. Is that the black box thing on top of the SC near the throttle body that has the big tube and all the other little ones going into it and has that one long screw with a washer? That needs a gasket, huh?

I'm in the process right now of replacing a lot of the rubber connections.

Here'* something I found. On that circular thing in the front of the SC near the throttle body, on the right side there seems to be a vacuum hose with nothing attached to it. Here'* a pic. Should it be like that?

Yes that is to be like that it needs to have a sponge attached to it like an air filter. Yes the big black block with the bolt running through it yes it needs to have a gasket under it or just GM gasket maker under it to make your own like I did.

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ACDELCO Part # 21913 More Info {#00801528, 801528}
FILTER,SPCHG BYPASS

Your right I can see the remains of a sponge there on that clip. It'* not too bad if I leave it without a sponge for a little bit is it?

The black box gasket seems like it could be my problem, because I think I have a vacuum problem.

Is there a torque setting for that black box? Also is there a torque setting for the bolt that holds in the bar with the 3 vacuum hoses going off of it (front of SC)

Just replaced all rubber connections and put a gasket on the black box. Car shifts nicely and idles steady! It worked!!! Thanks so much for your help.

Glad to help enjoy!