I now hate pedestal mount rockers. I have them on my 5.0 mustang, Crane rollers to be exact and they work great and are quiet. But those heads have never been milled and my block had never been decked. Not the story with my 400 that I just rebuilt. When I put the engine together on the stand I did what lots of guys do and how I had always done on my 5.0. Spin the push rod while tightening the rocker until it just starts to tighten, then go 1/4 to 1/2 turn. What I'm unable to check because the 5.0 is stored for the winter, is if the pushrod still spins when the rocker is torqued down, does the pedestal actually sit flush on the mount (I assume so or why else would one use shims) and when set properly does a stock rocker arm move at all or is it rock solid tight? I don't know if it is some lifters bleed down slower that is messing with my head or if I've collapsed some lifters from running too long a pushrod.

So where I'm at: Using the .060 pushrods, and sometimes shims, I have them torqued down and there is no slack in the pushrod. I can lift up on the rocker and feel it collapse the lifter a bit. To me this is set, but the rocker does move around a little bit, but it's not sloppy. My thinking is when there is oil pressure, the lifter pumps up and the rocker will be tight. Is this wrong? I've been trying to watch when the pushrod starts to collapse the lifter, call that zero lash and toque to 22 lbs making sure it happens in about a 1/4 turn and doesn't open the valve.

Will the lifter always bleed out before opening the valves? What I mean is sometimes I go to torque down a rocker and notice the valve is being opened so I try some shims and have too much slack and end up where I started and then the rocker isn't as tight as it was when I started and I haven't rotated the engine to create oil pressure.

Thanks for any advice you can give me.

 

If you get down to the basics, it is quite simple.
Shim the rocker arm for the correct valve geometry.
Adjust push rod length for proper lifter preload.

If the machine shop did their job correct, they should have the assembled stem height set so that there is minor shimming of the rocker arms.

 

You will need an adjustable pushrod to check push rod length. I think you are missing the big picture here. Pushrod length is determined by how centered the rockers tip sweeps the valves tip at zero lash. Starting on the base circle of the cam, being careful not to depress the lifters plunger, adjust the push rod untill you get it centered on the valves tip while turning the crank over. It should start in a little high of center and finish a little low of center. Then measure the adjustable push rod and add to that figure for a hydro cam .020 -.060 for the preload and that is the length you will need with no shims. It is important that the machinest keeps all the stem heights the same when doing valve and seat work.

 

The pedestal rocker arm is solid and is not going anywhere, The stud mounted rockers will move up and down the stud according to the push rod length AND dependent on how far you adjust the poly locks.
This movement of the rocker arm up and down on the stud affects the geometry. In the case of a hyd. cam, the lifters have about .175" of movement from very top to being bottomed out. The same push rod length can have different geometry locations depending on if you adjust them 1/4 turn to 2 turns.
So the pedestal rocker can not move up any, and the oil pressure in the lifter will not allow the rocker arm to move down very much at all. The lifter has to bleed down some, otherwise it will hold the valve open and you will then burn a valve.
So since the rocker arm is as you asked "rock solid" the geometry can not change without changing the rockers location.
And the push rod length cannot change the location since it is bolted down solid.

 

First you need a pushrod lenght adjuster(TFS-9002 from summit it's where a get mine 8.5" to 9.8"). With the pushrods lenght adjuster and a black marker you color the tip of the valve you want to set. install pushrod, rocker... on the base circle of the cam (valve fully close). Then turn the engine untill valve open and close. Remove rocker and look at the wear patern at the tip of the valve. It should be center with the tip of the valve. If not add/remove lenght on the pushrod adjuster until it's center.

When it's not center with the tip of the valve it will wear your valve guide quiker. Hope this help. Btw i use the same rocker on my 400 with deck block and shave head. Add to order custom pushrod from manley at the local engine rebuilt shop. 1 lenght for intake and 1 lenght for exhaust. Visit tech and tips from the manufacturer and they have pics

 

Adjusting push rod length will NOT affect geometry.
You have to shim the rocker to obtain the "sweep" you want on the valve tip.
Push rod length only affects the lifter pre-load on a pedestal rocker arm.
In fact with a hyd. lifter, you may not get a proper sweep pattern anyway if you are just turning the engine by hand. As you turn the engine over by hand, the spring pressure bleeds down the lifter and you will loose your actual valve lift and hence you will not get a %100 proper sweep pattern.
If you are familiar with shaft rocker arm systems like Crower, Jesel, T&D, their instructions say to shim the shaft system for proper sweep/or geometry and then you purchase your push rods to "fill in the space".
Our pedestal rockers are a fixed system just like the shaft system.
When we "fill in the space" on a hyd. lifter we add a little extra for the pre-load.

Really it is simple

 

I strongly disagree, push rod length is a major factor in determining valve train geometry. Shimming is nothing more than a last ditch effort to get out of buying the right length push rods. In most all cases the more you shim, the more you loose your valve train geometry. It should go without saying you would be using a light checking spring on the valve while finding your push rod length and always be watching to be sure the lifters plunger doesn't depress at all while turning the crank. You always want the sweep pattern as close to the center of the valve tip as possible for optimum valve and guide wear. I am more than familiar with shaft mounted rockers, but thats not the issue at hand here, from the original post.
"Our pedestal rockers are a fixed system just like the shaft system". The same principals apply when finding pushrod length.
After you find the length that gives you the best pattern, you measure it and then add to that figure for hydro cams .020-.060 for the preload.

 

Mark a, You are incorrect !! Pedastal rockers MUST be set up on rocker arm geometry with shims or milling of the pedastal to achieve the correct contact on the valve tip..... period. Pushrods are for lifter preload only. Example.... If my rocker arm geometry is on the money and I put in a pushrod that gives me 1 full turn of lifter preload from zero lash and I put in shims to achieve 1/2 turn of preload .....My preload may be correct, But now I just threw my rocker arm to far out bound for geometry. TMI is ABSOLUTLY CORRECT !!

 

Kind of strange that a newb just came in and out of all the threads he picks this one to comment on. but.
No, I am not incorrect. I have never milled a rockers pedastal, ever. Shims can be used if they don't throw the sweep pattern off to much.
"Pedastal rockers MUST be set up on rocker arm geometry with shims or milling of the pedastal to achieve the correct contact on the valve tip..... period." Why not just get the correct length push rods and avoid all of this nonsence ? You are taking a simple operation and going off in the wrong direction here.
"pushrods are for lifter preload only " I thought they were for activating the rocker arms ?
"Example.... If my rocker arm geometry is on the money and I put in a pushrod that gives me 1 full turn of lifter preload from zero lash and I put in shims to achieve 1/2 turn of preload .....My preload may be correct, But now I just threw my rocker arm to far out bound for geometry" .Anyone that goes by "one full turn, one half turn" isn't a pro builder. The correct way to check/set preload is to set up a magnetic base & a dial gauge on the rocker's tip so you will see exactly what measurements you are getting. Turns don't cut it in pro shops when we are setting up a new valve train. This is where you are getting confused in your statement, you should not consider preload when finding pushrod length, only add it on to the figure after you find the right length. You're line of thinking here is blured and you are backing yourself into a corner for no good reason here, So on once again, figure the right length out order them and just put them in and tighten the rocker down and go.
Oh I almost forgot, welcome to FTE

 

Well Mark,
I requested Tom to give his comment on this subject.
I am guessing you know who I am and the business we operate.
But that does not seem to mean anything to you, and that is entirely fine.
Being a professional engine builder does not mean that we don't make mistakes and we don't know everything.
But I wanted another Professional in the business give his opinion.
Tom is employed by Ford Racing. If you call the Ford Racing tech line, Tom is one of the guys you will get.
That's why this newb is here.

 

I am a pro as well, worked many years in the race engine business with a top builder who got his masters degree from Pit University in mechanical engineering way back when. Learned a lot from that man and he's done everything from NHRA to Nascar in all his years. And yes, that/you does mean something to me and everyone on here as well. I think it's great that someone keeps the 400 torch lit and offers so many good parts that you do.

 

mark a. i think your right. gonna try to find the complete article.

 

Mark a, Thank you for the welcome !! Nice to be here. If interested I would like to discuss with you further pedastal rocker problems in the future. Earlier I used the words milling of the pedstal for rocker arm geometry.... My bad, I meant to say milling of the fulcrum. ( I was in a hurry typing). Fourxfour, The side to side movement if you have some is normal operation. Tom

 

mark a. i thing your right. Your statement make more sense to me anyway.

Why, when i adjust the pushrod lenght to the maximum, the rocker almost fell off the tip of the valve ? That's goemetry to me.

 

Ok,
explain how the rocker arm being bolt down, sweeps differently by just changing push rod length.

Mark A... so what is your profession? who was the top engine builder?

Mustang81... what rocker arms are you using?