Adjusting Valves!

THere are 2 TDC's for each rotation of the cam - you have to be at TDC on the compression stroke for both valves to be closed/lifters on the base circle of the cam. If you're at TDC during overlap, then both valves are open - so it's not just "put each valve cylinder on TDC". If it's stud mount, you tighten to zero lash, then turn the nut another 1/2 turn and lock it with the set screw. IF it's pedestals, you tighten to zero lash, then tighten to 18-20 ft-lbs while counting turns. It should hit the torque in 1/2 to 3/4 turns - if it's more turns than that, use shims to reduce the number of turns required to hit the torque. If it takes less than a 1/4 turn to hit the torque, you need longer pushrods, or you need to remove material from the bottom of the trunion of that rocker.

there not self adjusters? in the 89 u shoudl just tighten to 12-15 ft lbs when both valves are closed, or lifters are down, then put it back to gether and go driving, it should all adjust them selfs, thats how mine worked.

blkstangman - there is a procedure for installing the rockers - it helps you know if the geometry is correct. If all is correct, you're right - you can bolt them on with the valves closed torque them (your torque spec is incorrect) to 18-20 ft-lbs. and drive on. The problem is, you don't know if the geometry is correct unless you follow the procedure. You simply got lucky. It won't always work out that way.

From comps website. All manufactuers are the same procedure. The image did not paste, but it is not important.



Adjusting Hydraulic Lifters for Proper Preload
In order to adjust the preload, the lifter must be properly located on the base circle or "Heel" of the lobe. See figure below.

At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.
1. Remove the valve covers, and pick a cylinder that you are going to set the preload on.
2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)
3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)
4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at "Zero Lash". Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.
5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.
6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.

Oh and I forgot to mention, if you follow the firing order, it can be a little quicker than picking cylinders at random or going 1-8. For solid cams, just set to your proper cold lash.

While you are there, get number 1 up to TDC with the valve covers off and drop in your dist correctly so the motor will be ready to fire up (new or dissasembled engines).

hllon4- the procedures you listed are for stud mounts; the pedestal mounts have a different procedure. Also, for the newbies, you can't just pick any TDC and stab the dizzy/install the valves. Has to be TDC on the compression stroke; TDC during overlap will have both valves open (not when you want to install the rockers) and will put the dizzy 180 degrees off.

Michael Yount,
how did i get lucky when i followed the book, everyone i talked to said 14ftlbs, the book says 12-15ftlbs, i didnt get lucky at all considering ive removed and replaced the rockers at least a half-a-dozen times on my familys mustangs.

blkstang - settle down there, no offense intended. My manual and my instructions from Crane for the FMS rollers all say 17-20 ft-lbs. My apologies - I should have simply said that my info on torque specs is different from yours. By lucky what I meant was simply that the cars you've worked on have the geometry/component dimensions that allow those rockers to come off and go back on as they were. Not everyone is so "lucky". The procedure for the pedestal mount installation is intended to highlight whether there may be problems when you crank the car up. Now that mine are set up (11 of mine required no shims, 4 required a .030" shim, and 1 required a .060" shim -- without those, mine make a helluva racket), I too can simply take them off, and retorque them -- provided I keep track of all the pieces and put them back as they were. When I start moving rockers/pushrods/shims around, the procedure is the only way to get things back to their proper low-noise operation.

Your post implied that anyone should be able to just bolt them on -- just because that's worked in your case doesn't mean it will work that way for everyone else. That's what I meant by 'it won't always work out that way'.

Michael Yount said:

hllon4- the procedures you listed are for stud mounts; the pedestal mounts have a different procedure. Also, for the newbies, you can't just pick any TDC and stab the dizzy/install the valves. Has to be TDC on the compression stroke; TDC during overlap will have both valves open (not when you want to install the rockers) and will put the dizzy 180 degrees off.

Click to expand...

Thanks. I overlooked that. I forget that everone does not have what I have. What is easy for some is a nightmare for others.
Gotta love a group effort!