This is a tool that is indispensable for adjusting the Q-jet. It comes with several different sockets for the various types of mixture screws you will come across. This baby gets right in there around the hoses and stuff that will be in your way. Blue Point, Snap-On, and others make it. I also discovered this neat item. On the 301 engines they used a ported vacuum advance valve that used a combination of manifold and ported vacuum. First there is a thermal vacuum valve on the head that denies any vacuum advance until the engine warms up. Once it is warm, the valve opens and the vacuum advance valve operates. First it gives around 10° of timing advance using manifold vacuum. Then as rpm rises, ported vacuum is added and even more advance is added. This results in a smoother idle, and more power across the rpm curve. I tried using this valve on my 1977 TA 400 and I was pleasantly surprised at what a difference it made. But remember, these were low compression engines that had EGR in place. You can get away with a lot more timing on engines like that. I never tried it on a high compression engine.