This is kind of a which came first, the chicken or the egg question:
Trick Flow heads, Roller Tip Rockers (1:1.6), ARP Rocker Studs, Hyd lifters

1. When all is said and done (assuming the correct pushrod is fitted with the correct contact patch on the valve stem), will the rocker base always be snug against the flair of the stud? Im not sure how to make that make sense, but basically, will the rockers pivot point, which the stud goes thru, be down against the bottom of the stud where it flairs outward, or will it be somewhere above it on the stem of the stud?

2. If the answer to 1 is yes: then how is lash set, because it can't go any 'lower' on the stud. If the answer is no, then how do you determine the correct pushrod length? Simply by determining the correct contact pattern?

My issue is, I dont know which comes first, pushrod length or the rockers fitment on the stud (as far as how high/low or close to the flair).

My guess is that the length of the pushrod (assuming again it is the correct length) keeps the rocker off of the flair, thereby allowing adjustment up and down of the rocker to reach the appropriate lash.

Thanks guys

which should have come 1st is - valve length, a longer valve will fix your problem, but a long (longer) enough push rod will work, as long as the pattern is correct or close on the valve tip.

Thanks 67RS - So does that mean the rocker shouldnt necessarily be resting on the flair of the stud in order to get the contact pattern correct?

The rocker will not be resting on the stud base when you have the correct length pushrod. Once I got the right centering over the valve stem tip, my rocker was raised! I was wondering too at the time.

On the Twisted Wedge heads I have sittin in the garage, the valves are too short,
and you cant put a short enough pushrod in it because the rocker bottoms out on
the stud, meaning I have to buy pushrods that are longer then what they should be,
according to the pattern.
you will have to set your pushrod length so the rocker isnt bottomed out on the
stud, and see if that makes a acceptable pattern on the valve.

Thats good news wrapped in an ugly package lol. At least I know what Im facing now, and wont spend another week scratching my head. Now I just need to get my adjustable pushrod set to get a good contact pattern.
Thanks again for all of yalls help.

Just an update for those that might be interested: (plus two questions)
I talked to a pretty smart guy at O'Reilly's today (the kind you used to find at NAPA). Here's part of my problem, the TF heads came with pushrod guides, washers and the studs. By removing the washer and fastening the studs directly on top of the guide plate, it effectively lowered the stud, while allowing the rocker to make good contact with the valve stem. The interesting thing is, after doing that, my stock pushrod makes a perfectly centered pattern while the adjustable rod set at .050 longer is a little off center, closer to the headers (TF recommends .050 longer by the way). I havent yet shimmed up my hyd lifter to run the contact pattern test, but in my mind (scary), regardless of the amount of depression of the cup in the lifter while turning the motor over, the stock length pushrod made the perfectly centered contact pattern. My thought is, if there was no depression of the cup (as if used with a solid lifter), the contact pattern may become wider, but still be centered. Is there any flaw in my thinking as far as lifter compression? I set the lash, without depressing the lifter cup, then 1/2 turn which slightly depressed the cup. Is that wrong?

FWIW: I found that a china marker leaves and even easier to read (crisper lines) contact pattern than a perminant marker did.

Jhunter most people will shoot for getting the valve stem/rock tip contact point to be centered on the valve stem. The most optimum setting though is to have the pattern just off center towards the centerline of the engine. this helps reduce the loading on the valve guides. When the valve begins to open the contact point is starting to move outboard away from the engine centerline, at half lift you want the movement to be stopping and when approaching maximum lift it should be starting to move back inboard towards the engine centerline. The bare bones minimum between the contact point and the valve stem edge is .020". Yunick explained it this way: "When the geometry is optimum, the rocker ratio will actualy increase during the initial opening phase of the valve cycle. As the point-of-contact moves outboard, the effective length of the valve-end clearance of the lever is increased. This helps accelerate the valve off the sear quickly. During the final phases of the cycle, as the valve is being returned to the seat, the point-of-contact is moving inboard and the effective length of the lever arm is decresing. This helps to slow the valve down just as it is about to contact the seat. Though not expecially critical on the intake valve, the latter effect is very important on the exhaust side."

You can make your own adjustable push rod tool from an old push rod, cutting and tapping it and inserting a fine threaded stud into the two halves, grind some flats on it to turn it with a wrench. I did this and it works great.

A lot of things effect the geometry. The twisted flow heads mentioned by some one could be as simple as the stud bosses were not milled enough for guideplates. When machining and converting to screw in studs it makes a difference how much material is removed if you plan on using guideplates or not. The first set of -461 heads that I milled when I cut them I set the machine up to remove the amount of material that my book told me. I didn't know this was for hex base screw in studs without guideplate. I ended up just like the twisted flow head problem, the rocker set down almost against the hex base of the stud. Longer pushrods solved my problem. But I also learned that no two manufacturers studs are the same dimensions. Dorman's would make this problem even worse due to the fact their hex base is .296" thick. GM's is .231, Summit is .219, ARP is .211. The other problem you run into when the stud sits too high is you run out of threads on the stud and the nut hits the shank. For this Summit's are worst with the threads starting .960" from the bottom of the hex base. ARP's are next worst for this situation at .952, Dorman is .949 and Gm is .806. While it looks like GM would be the best for this solution it is also the weakest and lowest quality stud of the four and by far the worst choice if your problem is the opposite and you stud sits too low because the GM is only 1.59" in lenght from the bottom of the hex to the top of the stud. All the others are 1.75".

I guess what I'm trying to say is try some different hardware, make sure your heads were machined properly for guideplates and try a push rod length tool to get your geometry nailed down just right.

SY1 - Wow, that was very good info, thank you very much for the time. I had to read part of it twice, but it actually makes sense. I just came back in after locking out my hyd lifter (as was the advise of another member, to effectively make it a solid lifter). After doint that I actually had the opposite of what you described as optimal. The contact pattern's distance from the edge of the inboard side of the valve was .145 and from the outboard side to the edge of the contact line was .112 . That gives a difference of .033 and a total contact roller pattern of .098. (didn't have my glasses on so might be off a .00x lol) That was with the stock length p/rod.
I'll have to see what .050 longer does to it, might get it a bit closer to where it should be. I do have an adjustable p/rod, so that will make it easier, just gotta get this thing figured out, then back to bodywork!
Thanks again for your help and explanation.

Edit - OK, I did it again, after posting, I realized that adding .050 to the p/rod will only push it farther from center, towards the headers. Grrrrrr. Maybe I should leave it at stock length, it simply doesnt make sense to go shorter than stock, now Im scratching my head again lol.
http://i21.photobucket.com/albums/b295/jaf31a/DSC01966.jpg

First off the rocker almost floats and shouldn't bottom out. The pushrod is pushing up and the valve spring is pushing up to keep it suspended.

I'm running protopline heads and they called for +.100 longer pr's. After assembly I borrowed an adjustable pr from a friend and got confused too. My stock length pr's were fine and gave a centered mark about .060 wide (looks as wide as yours). I can only assume it had something to do with the roller rockers I used or their info was for stamp steel rockers ?

DougG - I was able to get the rocker to float, I've got ample room above the stud flair/hex and plenty of space between the rocker and the spring, no contact anywhere. Just for the 'fun' of it, I may adjust my adjustable p/rod .050 shorter than stock just to see where it sits. The contact pattern looked great after removing the washer [lowering the rocker] but it was a hair on the outboard side as opposed to the inboard side. The roller rockers Im using are 1:1.6, so that might make things even more confusing w/ regard to the recommended .050 longer p/rods.
Thanks again guys

With my protoplines, which have valve stems +.100" , I had to go +.200 on the puhrods. This is using Comp Cam stainless 1.5' rollerrockers.

Found this over at TeamChevelle.(big sister site)


http://www.chevelles.com/forums/showthread.php?t=98752

We include a set of washers with the heads, Did you install the washer between the rocker stud & the guideplate? If you did, This is the reason for the lack of adjustment, Remove the washer & reinstall the guideplates/rocker studs.

We include those washers because if you are using a set of self aligning rockers you will not use the guideplates. The washers keep the rocker stud height correct & also protect the head from getting gouged.

DougG - Thats good to know, I had gone ahead and pulled the washers out cause it made sense to me, but at least I know someone from TFS confirmed that they weren't supposed to be there to begin with. I still end up with a contact pattern thats off center a hair, towards the headers, using the stock pr's. This weekend I'll mess around and see if .050 shorter than stock helps get it either closer to center or off center a bit, but towards the cam.
Thanks again