Rocker Geometry

[1961bluebug]

unfortunately most of pics from the past in this thread disappeared. Does anybody have a pic of their correctly set valvetrain geometry?

Thanks.

[mark tucker]

all most all of the ways to check & ajust geomatry will work to some extent.but are far from best. think about it why do you want your push rod in line with the rocker at 1/2 lift? there is only less than 1/2 of the spring pressure on it there.and that is it's strongest position.the push rod should be in line with rocker at or neer full lift, that is where all the spring pressure is.I know this will be neer impossiable with most of the rockers out ther.but there is another bennifit to this type of setup. the raito at the beginning and end of the lift cycle is much greater(the valve opens/closes quicker, not sooner but quicker, a lot of hp is lost on the flanks of the lobe,thus the hp advantage of a roller cam) on the foot type of rocker it needs to contact the lash cap as far inside as possiable,the raidus of the"foot"should almost roll across the lash cap as lift increases.(flat foot dont work,if you have flat foot it will need to be raidused or it WILL pull the valve over & cause extra wear on the valve&guide. and allways check your true rocker raito.the foot type are theoretacul raitos that add lift the more you lift them from rolingto the out side of the lash cap most 1.4's on a .400 lift are around 1.5-1.55 that will get you into truble.my 1.25 foot type are actuly 1.34 on a .415 lift cam witch is .038.& that could get you in to truble also. get the foot type rocker as low as possiable,I cut .05 off of mine to get what I could.there needs to be a new desgine rocker for these type 1 moters that realy works correctly.I am in the prosess of making some prototypes that will address these problems& more. and valve ajustment with crmolly pr.about any where from 0 to -.003 that will be defrent for each app. and dont for get the cam deflection of about .005 , when you ajust the valve the other valve is pushing on the cam the cam bends, mine bends .005. so it's kinda a juggling act.wach the valves on the other side pushing back & the same cyl valve pushing it away. stock type springs dont need to wory about this.but strong springs do.ever herd a louder taping from one cyl?but you just ajuster them. well think about it .004-.006 lash+a possiable .005 deflection or not. I run my valves at -.001 to -.003 cold lash.about .009 hot.(but I have a lot of thermol barrier coatings in my engine,so it dont swell every where or the same a normal one does)they spin over great for about 6 seconds when cold ,that builds enough heat in the cylinders to close the valves & vroom. runs great no problems almost 2 year old 2332 that gets the dog crap run out of it every day.(it's the only car I own) I am a retired performance machinest & engine builder(big moters572,632ci supercharged, NA,nitrous,etc) and racer. I dont like buying parts twice.do it right the first time.this is not rocket scince and I cant beleave that there still seting geometry the way they did it 35 years ago!!! I have a new well new to me mill on the way so I hope to have these rockers done by the end of the year for testing.

[vaughn bros.]

Using a +/- style dial indicater to measure lift and repeatability at valve. Just enough room for indicator tip to ride up and down beside the large valve adjusting stud. For me, I can get a pretty good visual on the alignment of valve stem and rocker stud at half lift when viewing it with indicator stem. Its just me but I like to stack up more than I need rocker shims and then whittle it down instead of starting at nothing and building up. I know the hate will start.

Also same indicator is large, and has a strong enough spring to push lifter back down against cam lobe during rotation. If indicator is weak, then your lift measurement may not be repeatable. Its just me and I know the hatin will start.

[cptcliffhanger]

I posted this sketch a while back, and nobody answered my question..

Is tis sketch the correct geometry at 1/2 lift?? basically 90 degrees all around

http://picasaweb.google.com/lh/photo/6tWspE7GEKDEHs43p1FBog?feat=directlink

[cptcliffhanger]

imbeding no worky.,.

[rsorak]

Yes the sketch is correct. You also want the arm wipe pattern to be in the center of the valve.
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Rick '71 Westfalia & '73 Thing

[cptcliffhanger]

thanks! think I get it.

[1961bluebug]

what do I do to move my wipe pattern down to the middle of the lash cap? This is a wipe pattern of CB 1.4 rockers on 043 heads, FK-8 cam, lash caps, approx 0.04 worth of shims under rocker pedestals. Or does it look OK to you? I believe my pushrods are too short, I´m at three turns out at this time.

Thank you.

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[nsracing]

Remove the shims. This will move the wipes down. Shorten pushrods accordingly.

[1961bluebug]

So, I got to this after a longer time.

How does this look? I thinned the rocker spacers a little bit and came up with:

And my second stupid question, I probably know the answer, but does the wipe pattern change with the length of the pushrod?

Thanks.
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[ach60]

[nsracing]

[thewreckingsoul]

is there a maximum amount of rocker shims that can be used? or is there a maximum allowable measurement when using rocker shims?
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[Desertbusman]

I just put my swivel ball adjusters back in after running stock adjusters again for a couple years. And it ended up taking .030" worth of stand shims. What NSracing says about geometry is true. The greatest bad forces working on the valve tips is at the highest lift and spring pressure. towards that highest lift is when you want the adjusters to be pushing straight down on the valve with less side pressure. Since my engines are just stockers I havn't wanted to play with different pushrod lengths but still attempt to get the perpendicular geometry set at about 3/4 lift.
Something I ran into this time was issues with the 8 x 1.25 rocker arm nuts. I torqued a couple nuts to about 17 ft/lbs and the nut threads stripped. The ones needed are stamped 8 (per the manual).
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71 Superbug
71 Westy

[turboblue]

[RockCrusher]

(mharney referencing Scat 1.4 rockers)

[RockCrusher]

[raygreenwood]

[RockCrusher]

I agree with you Ray and that's why I wouldn't compromise pattern for adjuster alignment. Given the choice...screw adjuster alignment and go for stem pattern. But getting both would be great. Calls for a new design I guess. What about Berg rockers....I've never even cast my eyes on a set?

RC
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[mharney]

Berg and CB are about the same.

I prefer the half lift method for the adjustable tips on either kind, because with each, there is a distinct benefit to doing it that way. If you start getting the cup too far rotated, you can pop out a pushrod or in higher mileage situations, wear out a cup. The oiling hole should be aligned on average too, so the engines I have put a lot of hard miles on have done very well this way. I prefer this, and haven't had a problem with it at all.

Really to get the net guide wear down perfectly, you'd have to integrate over the spring tension rate, taking a lot of readings at different lifts, or assume the K is somewhat linear, and find the point where you are in the midpoint of the side loading net. Too much bullshit for me, considering what little difference it would make.