Adjusting Valves??

Discussion in 'Fox 5.0 Mustang Tech' started by Shad, Mar 28, 2014.

  1. Hello to you all, this is my first post. I was going to do a search on this subject but couldn't find a way to do hear it goes. I have a '90 GT with a mildly modified 306 with Edelbrock Performer RPM alum. heads (#6025 with 2.02/1.60 valves)) with a Performer RPM 2 manifold, B303 cam & 1.72 roller rockers (stud mounted). I recently removed the intake manifold to replace the lower intake's gasket because there was a slight leak at the front/center of the manifold. While the intake was off I pulled the valve covers to clean & replace gaskets too. This is when I found a valve spring shim that had broken in two!! Luckily I was able to find both pieces & they matched up perfectly so I know there isn't any other pieces floating around in my motor...whew!! I'm still going to change the oil & possibly pull the pan just to make 100% sure though. I'm going to have to pull the rocker arms to find which valve spring has the missing shim & replace it, so I figured this was a good time to readjust my valves. I did this once before myself, but that was about 12 years ago & I've lost the documentation that explained exactly how to properly adjust valves (w/ hydraulic lifters) with the heads still on the engine. I watched a couple how to videos online but didn't see any that went about it the way I was told to adjust them all those years ago...which did work by the way. I remember starting with the engine at TDC adjusting intake & exhaust valves on certain cylinders (sorry can't remember which), turning the engine over 180 degrees & adjusting intake/exhaust on a couple other specific cylinders & lastly, turning the motor over another 90 degrees and adjusting the valves remaining. Does that sound familiar to anyone? The how to videos I pulled up recently started at TDC adjusted #1 cylinder, then turned motor 90 degrees & adjusted the next cylinder in the firing order, then another 90 degrees & onto the next cylinder in the firing order sequence, etc. However, I don't remember turning the motor over that many times. What exactly is the proper way? Any help would be greatly appreciated!

    Sorry for the lengthy post!
  2. Michael Yount’s valve adjustment procedure

    Here's an easy way to determine this. Start with the #1 cylinder. Rotate the engine with a ratchet on the crank bolt clockwise. Watch the #1 pushrods. First the exhaust pushrod will rise and fall signaling what would be the exhaust valve opening and closing if the rocker were on. As it closes the intake pushrod will rise -- keep rotating clockwise until the intake pushrod falls and is level with the exhaust pushrod - both at the same height. Both lifters are now on the base circle of the cam - both valves would be closed if the rockers were on.

    Now, install both rockers. Tighten the bolts with one hand while rocking the rocker with the other hand - continue until you reach the point where you can't 'rock' the rocker any more because there's no gap on the valve stem end or the pushrod end. You are at zero lash - i.e. - no gaps. Stop tightening just as you reach this point.

    Now, put your torque wrench on the bolt and tighten it to 18-20 ft-lbs while counting the number of turns it takes to reach the torque. You should hit the torque within 1/4 to 1 turn of the bolt. If it takes more than 1 turn, use a shim to raise the rocker -- each .030" shim will reduce the number of turns to torque by about 1/4 turn. If you reach the torque in less than a 1/4 turn, or you have trouble reaching zero lash even at full torque, then you'll either need longer pushrods, or to CAREFULLY remove some material from the bottom of the rocker fulcrum. Using the procedure described above, you will work through the remaining 7 pairs of rockers. If you follow the firing order, it will minimize the manual cranking you have to do to get the lifters on the base circle of the cam prior to installation of the next pair.

    When I first went through mine, 13 of them took no shims; 3 of them took 1 .030" shim. Upon cranking it up, one or two of them sounded a bit noisier than I thought was right, so with the engine hot, I pulled the upper off, and the valve covers, and went through the installation procedure again. That time, 11 of them took no shims; 4 of them took one .030", and one of them took one .060" shim. And they were very quiet running.

    Good luck with it.
    Michael Yount - K'ville,TN 82 Volvo 242w/5.0L; 2000 Suzuki Bandit 1200
  3. I thought the RPM AL heads had stud mounted rockers. In that case you just turn the nut to adjust valves. There's no shimming involved.
  4. I simply look at which lifters or rockers for a given cylinder are all the way up (on lobe). When I see this on a given cylinder, it means that the other lifter for that same cylinder must be somewhere on its base circle and in position for adjustment. Its the quickest, easiest and most fail safe method in my opinion.
  5. I forgot to add, if you can't remember which ones you've adjusted using the method I describe, just put a small piece of masking tape on each rocker when you adjust. When they're all marked, you're done.
  6. Thanks to you all for the replies! Yes, the Performer RPM 6025 heads are stud mounted. I haven't opened the edelbrock link yet (on my lunch hour & pressed for time) but I guess what I was referring to is if I have to go about it the way that I originally described, find TDC adjust #1 cylinder, then turn motor over (clockwise) 90 degrees & adjust the next cylinder in the firing order, then turn motor another 90 degrees & onto the next cylinder in the firing order sequence, etc. The way I remember doing it all those years ago...was that I was able to adjust more than just 1 cylinder at a timewhen the motor was at certain degrees, ie. TDC, 90 degrees & at 180 degrees. Is that even possible?