slt200mph

iTrader: (42)

I guess I better ask who are "the big boys". After 45+ years of hot rodding I thought that I knew who the big boys were. Please share with us the identities of "the big boys".

vettenuts

iTrader: (4)

Not really an issue of proper design. If you design the rocker for a specific valve stem height and pedestal height and it fits perfect, next time you get a valve job and the valve stem height changes then the geometry will be off. The method for correction is the alter the height of the rocker pivot point. Stock rockers have the same requirement once you deviate from the stock cam and head setup. The geometry will change and only through altering the rocker height can it be corrected.

So if you consider all the tolerances involved and combination of parts, having to alter the pivot point height of the rocker to adjust it to a given combination is a requirement. With a stud mounted rocker, the height adjustment is made with either the poly-lock or the pushrod length with the end goal being the same. In my opinion it is all part of setting up the parts combination correctly no matter what rockers are used, including stock.

taman86

iTrader: (19)

wow, so in reality there is alot more then just getting a different set of rockers. if you change one then you have to change it all. but if you dont have the right tools to take the proper measurements then you wont really know if its off either. unless you take it to an engine builder who knows what they are doing to get the right setup, but 90% of the average diy backyard mechanic who likes to work on their cars wont check things like this. they are all simplicity, slap it together, torque it down, and go.

vettenuts

iTrader: (4)

Actually, a lot of the tools are relatively inexpensive. Check springs are a few bucks. I used different washers for shims on the initial check then ordered the correct shims. An adjustable pushrod is under $20. A dial indicator is a little more but in a pinch an accurate rule could be used.

taman86

iTrader: (19)

never heard an adjustable pushrod before, alot of these things you're talking about ive never heard of before and sure as **** wouldnt know how to use them besides a dial indicator but at the same time the person using these will have to know the exact tolerances of the of where the springs heights are supposed to be, rocker heights, etc., otherwise they will be taking a shot in the dark. but i guess the manufacturers of the cam's, rockers, springs, pushrods will know the installed height tolerances and the mechanic can adjust them as needed.

vettenuts

iTrader: (4)

Adjustable pushrod is a simple tool. It comes out of the box at 6.800" in length and then you simply unscrew it to make it longer. Each turn that you unscrew it increases the pushrod length by 0.050". You use it to find out what length pushrod provides zero lash on the rocker with the valve closed, then simply add your lifter preload to get a final pushrod length.

Check springs are very light springs that allow you to open the valves by hand. They are used for making several different measurements and when done the valve springs are re-installed.

03supercobra

iTrader: (38)

Good info here!

I do agree with some of the other posts, the stock rockers are decently light and simple to install. With the trunion upgrade, they are good for the majority on this board, BUT some of you should look at the geometry of a stock rocker on a higher lift cam, tends to wear out valve guides quickly.

taman86

iTrader: (19)

ah, neat. so these tools can be had from any general auto parts store, or are they specialty tools that ca =n be found from dealers? im all for doing hands on learning, you can read and read on how to do it, but until you get your hands dirty and do it for yourself, you wont gain any knowledge. even if i do stay with the rockers i got, i still wanna tear into my engine just too see how these things work and get that little tidbit of 'know-how' under my belt. i mean any monkey and put together an engine, but to do it correctly is something entirely different and can learn something knew everyday.

but let me piece this all together here...with the rocker arms installed to proper torque, the valve should be fully seated afterwards and the pushrod at zero lash with no "pre-load" i guess is the word im looking for, on the lifter meaning that the lifter shouldnt be compressed right....so if it aint, say that the valve isnt fully seated, then the said mechanic would then have to install shims under the rocker arm bearing which consequently would raise the rocker arm up, but then the pushrod would not be long enough and would negate zero lash so thats when the adjustable pushrod would come to use to see exactly how long of a pushrod you would need to get the proper length of a pushrod to get the correct geometry for the valve to be seated and the pushrod and lifter at zero lash right....is there something im missing about the concept of valvetrain geometry?

vettenuts

iTrader: (4)

With the rocker in place and lifter on the base circle of the cam (valve is closed), the valve can't be partially open unless there is something else wrong. The spring should be holding it closed. Then you use the pushrod to basically measure the distance betweent he pushrod cup in the lifter and the pushrod cup in the rocker with the rocker touching (lightly) the top of the valve stem. This measurement is zero lash. Since the pushrod cup is up, you now would add the lifter preload such that the final pushrod that you buy would depress the lifter cup by a known amount.

However, the pushrod measurement is taken after you set the rocker wipe pattern on the valve stem as any shimming or change in height that you make to the rocker in order to properly set the wipe pattern will then effect the pushrod length because you have raised or lowered the rocker pushrod cup relative to the lifter cup.

So the steps would be:

1. Set rocker height to optimize the wipe pattern. See link: Link
2. Measure for the pushrod length required to obtain the proper lifter preload based on the rocker height that has been set in the first step. See link: Link

taman86

iTrader: (19)

holy crap, ok, got it. and thanx vettenuts for the all the info. you are one knowledgeable guy and dont have a problem helping retards like myself. keep it up and thanx again for everything and all the advise. there really ought to be a sticky up on how to properly do what you sent me for people wanting to know how to do it like myself.

02*C5

iTrader: (1)

Stock rockers here with trunnion upgrade .615 lift and to this date no issues at all. If it was a TF head or any after market head I would definitely say yes, but if its a 243/799/241/... or any GM casting the lightest rocker with the best geometry is going to be the stock rocker. Oh and she shift at 6800 w/ a 7K redline.

SweetS10V8

iTrader: (4)

Stock Rockers with Comp trunion upgrade (only $135) and I run .621 lift and 7000RPM

taman86

iTrader: (19)

hey 02*C5, what part of AZ you live in, im in Safford

Irish350

iTrader: (14)

is this just ls1 rockers? I was planning on running a cam up to 6700 or so with ls3 rockers..

When i did my heads/cam on my old lt1 i went crazy adjusting the rockers, when i got into lsxs i loved that they didnt need to be adjusted (in the traditional sense), but after all the research ive done for my current build Im more and more inclined to have a pro do it.

taman86

iTrader: (19)

ya this thread was for ls1 rockers, the difference between the stock rockers with the trunnion upgrade and roller rockers then it turned into how to properly install and get the proper valvetrain geometry. ive never heard of using ls3's on an ls1?

Irish350

iTrader: (14)

yeah, i guess since its in the gen 3 section that was a dumb way to phrase it.. i guess i meant are the limitations similar with the ls3 rockers (thatll be on ls3 heads), ive heard people do trunion upgrades on ls7 rockers if memory serves...

done threadjacking, just had me interested.

SweetS10V8

iTrader: (4)

I run LS3 heads and rockers, they all are the same as far as the trunion is concerned.

vettenuts

iTrader: (4)

GM upgraded the rockers back around 2003 (may not be exact on date) to eliminate the problem. So the need for the trunnion upgrade will depend on the year of the car. I think the f-body's ceased production prior to the upgrade but the new rocker was put into the later C5 Vettes.

taman86

iTrader: (19)

well aint that peachy. 03+ gets the standard gm upgrade while the 02 and earlier has to pay. kinda like getting an 01-02 f-body with the upgraded clutch system while the 00 and earlier clutch system is garbage.

lubelizard

iTrader: (5)

So an LS2 does not "need" the trunnion upgrade? My interpretation of all the trunnion threads here were that almost all LS based engines could benefit from them.