Reply With QuoteShaun for some reason I cannot upload. Gallery won't take it. Email me and I will send you something.
You're making good sense, and looks like you're doing it right. It's very difficult to see the valve stem...but if you use your critical eye, you can be very accurate in determining 90*. You're using the centers of the trunion and roller tip correctly.ok, stealcomp you wrote me up something a while back that i printed out and I'm pretty sure i understand what your saying but i wanted to get your input as well as others like fiat, gofast, infomatic, and anybody else who knows what they are talking about.
From my understanding to get the perfect length i want to make sure the rocker is 90 degree to the valve stem while at mid lift. To find squareness to the rocker you talked about the trunions (sp) and i'm guessing, because i don't know for sure, that those are the axle type shafts that go through the middle of the rocker and the roller tip. You talked about machining marks and if i understand you correctly i should use the center of these two as a way to align my straight edge and then compare the square end to the the valve stem?
Here's a pic i took, kinda shows what I'm doing..
http://reitanfamily.com/gallery/d/21026-1/DSCF6315.JPG
Another pic, but hard to see valve stem...
http://reitanfamily.com/gallery/d/21038-1/DSCF6319.JPG
Also stealcomp, you talked about pushrod length not having anything to do with where the trip of the rocker is.... The more i extend the adjustable push rod tool the more forward the tip seams to be moving on the rocker.. Also i noticed a few time that the rocker was alittl off to the side of the valve tip, if i release the pressure on the rocker twist it a bit so that the push rod is centered on the guide and not touching one side or the other this is corrected... but whats going to keep things from not moving all over the place, do i have too much play in my guides or maybe this tool is just a bit skinnier than it should be? Now that i think of it there were two sized push rods that could be used 3/8 and 7/16 if i recall correctly, maybe i bought the guides for the beefyer pushrods? Just throwing that out there... i could be making no sense right now
Because the pushrod comes off the lifter at an angle, it will push the rocker to one side when it's under spring pressure. When it's at the lash point (on the base circle of the cam lobe), everything's floating around a little. This is what gives a mechanical valve train it's cool sound.Just look at the direction the pushrod is leaning, and that'll be the direction it's going to push the rocker. Use that to help determin what's centered side to side, and what's not, AFA roller tips.
The more i extend the adjustable push rod tool the more forward the tip seams to be moving on the rocker..
This is correct...at mid lift, the roller will be at it's furthest distance from the center of the valve tip. (Again, see the diagram)
Last edited by shaun; 11-17-2010 at 08:30 AM.
Shaun for some reason I cannot upload. Gallery won't take it. Email me and I will send you something.
steal thanks for the great info, although it was obvious and i just didnt see it i now understand why the closer i get the rocker to 90* at mid lift why the tip looks to be moving more forward. I think i got down what i need to do, it's really not all that easy to see the valve shaft with the springs on and the square held up to it but i with some paitence i will get it... I'm not sure where i'm at now but last i measured which was close i was 15 turns out on my push rod checking tool... each turn says it's .050.. according to that so far my length is about 9.550, course i need to go back out there and make sure i'm square. Also that was the exhaust...
Shaun for some reason I cannot upload. Gallery won't take it. Email me and I will send you something.
Dont have your email, you can upload using my dilio... http://unix-scripts.com/hb/ too if you want to try it.
LOL. I got 1/2 of it uploaded to your site. But other half won't go.
Update. Many time outs later....it is there. Pay no attention to the pencil notes of many camshafts ago.
Meanwhile you can go here and read till your eyes bleed.
http://www.mid-lift.com/MASTER-INDEX.htm
first your head explodes, then blindness set in
Steel I am impressed, 99.9% of the people out there have this completely jacked up. There is some effect from running longer or shorter rods to effect lift events (sooner or later) but it ends up changing your max lift also and I don't seen any real benefit from it, if you find the need to that just get a differant cam. Also Dart makes an adjustable guide plate because they got fed up when the stuff out being so inconsisdent.
Installed height will also effect roller location...the taller the installed ht, the closer the tip of the valve is to the rocker stud, making the rocker seem long. This usually only haappens with 2.100 or more installed ht, so I wouldn't worry about it.
when useing the term "installed height", what is it being refered to? installed height of the valve stem tip? how can this be changed without useing either longer or shorter valves, and/or grinding the valve stem itself? im sure i am a little confused since i normally refer to installed height with the valve springs, not the actaul valve. obviously valve spring installed height would have no corilation with rocker geometry. so is it common practice to grind valve stem tips?
when useing the term "installed height", what is it being refered to?
in trying not to step on Steel's words here, as the push rod gets longer and the rocker sets higher the tip gets closer to the stud, and visa versa. But his is not the way to set up your push rods contrary to what Comp Cams and a lot of others say. Where the tip falls on the valve is the job of the rockers length from the fulcrum to the tip, not the pushrods length. So when you have your pushrod length determined using the method he discribed, the tip falls where the tip is going to fall using that brand(type) rocker.
Installed height is the reference to the height of the valve spring in the closed position, so you are right there. There can be variations based on longer or shorter valves. There can also be variations due to the condition of the valve seats. If the seats have been cut a number of times and the valves are "sunk" into the seats further than normal this also affects the installed height, and thus where the tip of the valve is. Now with the tip of the valve being higher due to any number of these reasons, the rocker has to be positioned higher on the stud to get better geometry, thus pushing the roller tip further toward the outside of the valve tip. That happens because the valve angles toward the rocker stud decreasing the distance between the two. Did that make any sense?
Paul
I think Steel was stating that not to get to concerned with the tip location on the valve and don't try to change it's location by changing the push rod length, it's ludicrous and wrong, there is one correct rod length and has nothing to do with where the tip is located on the valve. That's the job of the rocker/manuf.
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