Well I finally got the time to take the carb apart today. With the help of my bud Greg we did some tear down and research for you guys. The first pics of the two carbs are for reference. One is the 81 and the other is for a 74. Other than the electronics on the 81 there's not a lot of difference between how they really operate. 4M and an E4ME for reference. The mistery of the boost referenced power valve is forever solved as well. There's very little difference between the NA cab and the boost reference one and you CAN make one if you have the right parts. I'll explain this as I go through the pics. Both Greg and I are suprised no one figured it out but since we have and now know how to do it you guys are gonna have a fit. And it's so simple even a newby could do it if you have a a drill press and basic metal working skills. I think this means you can do it as well Aj. LOL (you knew it was coming):biggrin: The first pic is of the base plate. This is the most important part and without it you can't have a boost reference to the power valve. As you can see I used straws so you can see where the port is. This port is what Makes the carb so special. It doesn't alow vac to influence the power valve. It isolates it so you can use the boost for a reference to keep fuel flowing when you let off the throttle.