[PontiacMatt72]

What method do you prefer for establishing valvetrain geometry?

*in a perfect world, one could have the narrowest wear pattern perfectly centered on the valve tip and a perfect 90* rocker angle in relation to the valve. This post is asking you to pick one option.*

1: Centered wear pattern on the valve tip (examining the sweep of the rocker tip on the valve stem tip) *regardless of angular geometry in relation to the rocker and the valve*
http://www.lunatipower.com/Tech/Valv...nGeometry.aspx

2: "Mid-Lift" method (line from center-of-trunnion to center-of-roller to be 90* to valve at half of the gross lift [at the valve]) *but not necessarily a centered wear pattern at valve tip [but at least .020" or more from edge of valve tip])
https://www.google.com/amp/www.hotro...-geometry/amp/
https://m.youtube.com/watch?v=o5is9BsH5OU


3: A compromise between the centered wear pattern method and the mid-lift method

4: Narrowest wear pattern at valve tip regardless of angular geometry and centered wear pattern

5: Method in which rocker tip starts on the "intake side" of the valve tip (valve closed), and travels furthest outboard toward the exhaust side of the valve tip at max lift. (Refer to Diagram A" on page 1 of the below link)
http://www.compcams.com/Technical/In...20Geometry.pdf

[tom s]

I call a guy that knows exactly how to do it,he makes a house call,tells me what to order and its done.Tom

[Jack Gifford]

I voted for #2.

#4 isn't really meaningful. If you could measure it accurately enough, you'd find that #2 gives the smallest travel across the valve tip, since the travel is half outward and half inward (during valve opening).

[steve25]

Not to place a bug in the ointment, but ware is very dependent on the spring load, not just the sweep, so as the valve opens and the pressure goes up there is more possible ware being applied along with the amount of sweep.

Another thing along these lines to concider is that if the geometry is off some while the valve is closed or near closed, at least there is a lot of valve guide lenght to support the valve .

[KEN CROCIE]

solving FOR # 4 will give you # 2. The illustration in the Comp Cams cat. is just WRONG ! (#5)

[Tom Vaught]

Agree with Jack and Ken, at the end of the day #2 is the place to be.

Comp has had a bunch of stuff wrong over the years that really screwed people up.

Many would love to have a Tom S. "I know a guy" to set up their valve trains for them, LOL! Nothing wrong with that if there is a guy somewhere close to you that really knows.

Tom V.

[tom s]

He cam over and degreed the cam also!Tom

[Tom Vaught]

You have Too Many "Really Good" Friends, Tom S.

Tom V.

[cgeise]

FYI Jesel and TD take different approaches to there rocker arm geometry don't use one checking tool on the others product or you have big problems -- one company build stuff for more of a centered sweep thru the complete lift cycle and the other is more centered on narrow sweep at half to max lift -- we had MAJOR ISSUES with my sons car until we got it figured out

[grnmnstr]

Narrowest band as close to the middle as possible. Keep shimming (or remove) until you get as close as you possibly can. Don't just settle for what it is with what you have. Proper machining of all contact points in the head is critical, especially valve spring pockets. Make sure they are all uniform, end to end.

THEN order correct length pushrods.