I just finished putting heads and cam on my 1990 GT. I went with the Performers with the thermactor plugs installed in the heads (smog pump lines plugged). The smog pump is still on the car but is only feeding the line that runs down to the H-pipe (currently has an off-road H). The other line from the smog pump (thermactor) is open and just blowing air into the engine bay. The cam is a comp cam with 212 intake 224 exhaust at 0.050 and .512 gross valve lift with a 114 centerline. Also installed were D.S.S. 1.6 ratio roller rockers and a Comp Cams double roller timing chain. On top of all this sits a Kenne Bell twin screw blower.
The problem (maybe it's not a problem 'cause the car runs like a raped ape on acceleration) exists when I let off the throttle on the highway at normal cruising speeds in any gear. When I let off of the throttle, the engine starts to drop in rpm, then 3-5 seconds after I had let off the throttle, the engine loads up like someone just turned the A/C on. This then lasts for about 3-5 seconds, then whatever is loading up "releases" and the car feels normal decelerating all the way down to a stop. I have a hunch, this has something to do with vacuum actuation of some device. The boost gauge pegs down to 22 inches of vacuum when letting out of the throttle and all this is going on.
This is more than an annoyance than anything else because I'm not used to it. The Kenne Bell was on the car before I did the heads and cam and it never did this. I'm wondering what the heck it could be. Sorry about the lengthy story but I felt in order to get a good answer I needed to provide a good description.
The problem (maybe it's not a problem 'cause the car runs like a raped ape on acceleration) exists when I let off the throttle on the highway at normal cruising speeds in any gear. When I let off of the throttle, the engine starts to drop in rpm, then 3-5 seconds after I had let off the throttle, the engine loads up like someone just turned the A/C on. This then lasts for about 3-5 seconds, then whatever is loading up "releases" and the car feels normal decelerating all the way down to a stop. I have a hunch, this has something to do with vacuum actuation of some device. The boost gauge pegs down to 22 inches of vacuum when letting out of the throttle and all this is going on.
This is more than an annoyance than anything else because I'm not used to it. The Kenne Bell was on the car before I did the heads and cam and it never did this. I'm wondering what the heck it could be. Sorry about the lengthy story but I felt in order to get a good answer I needed to provide a good description.
