Witness mark WIDTH on valvestem tip

So I have been testing some pushrod lengths, p51 heads, Crower rockers and Crower roller lifters. So far been getting marks in the 1mm (.040), to 1.5mm (.060) WIDTH. This is with cam in the .790 I lift and .814 E lift. My question is, is this in acceptable range, or does it need to be even narrower. (Yes I know, backwards engineering method). Thanks!

I would say as long as it is centered on the valve tip it will be fine.

glenevans wrote:...I have been testing some pushrod lengths..been getting marks in the 1mm (.040), to 1.5mm (.060) WIDTH...is this in acceptable range, or does it need to be even narrower...

If you are confined to the "minimal sweep" theory of valve train setup, then you could go with the narrowest pattern on the valve stem tip. It is not ideal geometry, but it will (sigh) suffice in most cases.

Also, forget about where the roller tip rests atop the tip of the valve stem, for it has nothing--absolutely nothing--to do with valve train geometry. So let the roller wheel fall wherever it may and focus on the "geometry proper" instead.

(The roller wheel is not on the tip of the rocker arm to reduce friction as most people mistakenly believe, it's actually put there specifically for aiming the forces of the rocker tip against the valve stem to remain continually inline with the valve stem as the rocker arm traverses through its radial sweep, thereby all but eliminating side-loading relative to rocker arm articulation.)

Paul Kane wrote:

glenevans wrote:...I have been testing some pushrod lengths..been getting marks in the 1mm (.040), to 1.5mm (.060) WIDTH...is this in acceptable range, or does it need to be even narrower...

If you are confined to the "minimal sweep" theory of valve train setup, then you could go with the narrowest pattern on the valve stem tip. It is not ideal geometry, but it will (sigh) suffice in most cases.

Also, forget about where the roller tip rests atop the tip of the valve stem, for it has nothing--absolutely nothing--to do with valve train geometry. So let the roller wheel fall wherever it may and focus on the "geometry proper" instead.

(The roller wheel is not on the tip of the rocker arm to reduce friction as most people mistakenly believe, it's actually put there specifically for aiming the forces of the rocker tip against the valve stem to remain continually inline with the valve stem as the rocker arm traverses through its radial sweep, thereby all but eliminating side-loading relative to rocker arm articulation.)

Paul ... most people refuse to even try to grasp those correct facts. They want to be told some easy way to get it right.
The WIDTH of the pattern really has no meaning which can indicate correct geometry everywhere.
JESEL suggests a very wide pattern starting at the inside and progressing to the outside of the valve tip, (NOT edge riding though), when going through the lift cycle, (similar to a sled, non-roller rocker arm tip), because his rockers are designed that way to lessen all important pushrod cup deflection. Lots and lots and lots of very high end engine people recommend and use his stuff without any issues.

Dunning & Kruger effect is always in play here.

Just thought if it was a big problem that maybe each rocker arm could have its very own checking tool that sets in its place while testing. But suppose things like ultra high lift might not give ideal results. What are your guys thought on the cheap plastic push rods checkers? I like the ideal getting the stud to rocker at 90 degrees at half lift method, but I'm no expert.

Randy has it nailed down! I want to know the easiest way for the "home garage guy" to get an acceptable pushrod size. I have read dozens of geometry articles, half of which seem to emphasize something totally different than the others. So in the end, a narrow pattern seemed to be mentioned multiple times. There seems to be some simplistic methods all the way to very complicated. So what is best for the home garage method??? Thanks!

glenevans wrote:Randy has it nailed down! I want to know the easiest way for the "home garage guy" to get an acceptable pushrod size. I have read dozens of geometry articles, half of which seem to emphasize something totally different than the others. So in the end, a narrow pattern seemed to be mentioned multiple times. There seems to be some simplistic methods all the way to very complicated. So what is best for the home garage method???  Thanks!

I don't know how to explain it simply ... with a ROLLER TIP rocker arm, the valve side can be pretty variable; getting the angles nearer correct for load carrying ability on the pushrod side is the most important, especially with high valve spring pressures.
Usually, finding the best compromise of both sides is the best but, there is no simplistic, easy way to get there.
With the big block Ford ... even the intake and exhaust sides are different from one another.

Most articles and directions have the small block Chevrolet valve train in mind and of course, that is not the only pushrod engine out there.

Thanks for all the information!!!

"I" try to minimize the angularity ( and change) on the pushrod side. Maybe this is a carry over from doing FE engines but "I" found the valve train to be more stable when I so it that way. if the rocker pivot length is correct on the valve side , the pattern should be centered well enough. I agree with Randy that a wide sweep is not a bad thing.

glenevans wrote:So I have been testing some pushrod lengths, p51 heads, Crower rockers and Crower roller lifters.  So far been getting marks in the 1mm (.040), to 1.5mm (.060) WIDTH. This is with cam in the .790 I lift and .814 E lift. My question is, is this in acceptable range, or does it need to be even narrower. (Yes I know, backwards engineering method). Thanks!

What you have there will work just fine.