Valvetrain geometry video

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Did I miss it? He changed the pushrod length .150 . Did he go longer or shorter?
Good info for a magnum head small Mopar, pushrod length doesn't do anything on a shaft rocker.
 
33IMP said:
Did I miss it? He changed the pushrod length .150 . Did he go longer or shorter?
Good info for a magnum head small Mopar, pushrod length doesn't do anything on a shaft rocker.
Click to expand...


Shorter. That only works with antiquated stud mounted rockers.
 
Dan the man said:
I thought that somebody here said that valve train geometry can be changed at home with basic hand tools, is this correct ?
Click to expand...

You asked if it could be done at home with basic hand tools.... and you were told no - it requires specially machined spacers to move the rocker shaft centreline on a shaft mount system.
If you have stud mounted rockers pushrod length will alter the geometry as demonstrated in the above video.
 
33IMP said:
Did I miss it? He changed the pushrod length .150 . Did he go longer or shorter?
Good info for a magnum head small Mopar, pushrod length doesn't do anything on a shaft rocker.
Click to expand...
Unless I'm missing something here that's not true. If push rod length is to short the valve's will not open the full amount. To long a
Ted265 said:
You asked if it could be done at home with basic hand tools.... and you were told no - it requires specially machined spacers to move the rocker shaft centreline on a shaft mount system.
If you have stud mounted rockers pushrod length will alter the geometry as demonstrated in the above video.
Click to expand...
Ted265 said:
You asked if it could be done at home with basic hand tools.... and you were told no - it requires specially machined spacers to move the rocker shaft centreline on a shaft mount system.
If you have stud mounted rockers pushrod length will alter the geometry as demonstrated in the above video.
Click to expand...
I think that I'll just run a small cam and if it runs decent that's fine, if it doesn't oh well.
 
33IMP said:
Did I miss it? He changed the pushrod length .150 . Did he go longer or shorter?
Good info for a magnum head small Mopar, pushrod length doesn't do anything on a shaft rocker.
Click to expand...
I've made that statement before and gotten argued to the FLOOR over it.
 
The valve stem height sets the stage...everything else revolves around it whether or not its correct. Rocker has to be at the right height for stud mount and shaft..with shaft also needing pulled back in most cases.

Shaft mount-You can negatively effect the geometry at the adjuster with too short a push rod.
 
Yes, you can negatively effect the adjuster (been there, done that) with too short a pushrod on a shaft rocker..... but that doesn't change the rocker geometry.
 
With shaft mounted adjustable rockers the pushrod length and how much or little the adjuster is threaded into the rocker body can affect actual valve lift. Give me cup adjusters and then a measuring pushrod to try and find maximum lift as long as there are no induced clearance problems. Adjusters as far up as possible (w/clearance) or with some arbitrary thread count exposed below the rocker doesn’t guarantee maximum valve lift. Many here know this obviously. Anyway, Sounds like geometry to me.
 
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What a resume he has! Old school Doctor of horsepower they are dying breed.
 
33IMP said:
Yes, you can negatively effect the adjuster (been there, done that) with too short a pushrod on a shaft rocker..... but that doesn't change the rocker geometry.
Click to expand...
Rocker geometry is designed in.
"Rocker geometry" is a generic term thrown around representing the entire cast n crew.
"Valve train geometry" takes longer to say.
 
MOPAROFFICIAL said:
Rocker geometry is designed in.
"Rocker geometry" is a generic term thrown around representing the entire cast n crew.
"Valve train geometry" takes longer to say.
Click to expand...
Agree! Shape, arm length, angle, is all built into the rocker when it's built. Hard part is getting valve height right for the rocker your using.
 
33IMP said:
Agree! Shape, arm length, angle, is all built into the rocker when it's built. Hard part is getting valve height right for the rocker your using.
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Between that and spring/lift.
It's getting easier nowadays. More choices.
 
If the push rod is to long wouldn't that cause the lifter to bottom out? As lifter preload is 0.045" right? Push rod to short and the valve will either not open all the way or not at all, so accurate push rod length is important. Valve stem length should be checked out by your machinist.
 
This one talks a little more about the differences between the stud mounted stuff versus the shaft applications. Good little video.
 
SSG_Karg said:
This one talks a little more about the differences between the stud mounted stuff versus the shaft applications. Good little video.
Click to expand...

One of these days, I'm going to have to do some YouTube videos about rocker geometry. There is some good basic info in these, but also much that is incorrect. I wonder if either of these gentleman can explain how the centered pattern improves reliability or performance, or any other benefits. Also, if the rocker ratio is changed by changing the pushrod length, why is there a need to sell multiple rocker ratios. Just buy any old rocker and set it to the ratio you want. If only it were that easy.
 
Rocker ratio is a nominal ratio & hopefully somewhere from valve-closed to valve-open, the ratio is achieved. A 1.5 rocker might have an opening rate of 1.4, reaches 1.6 at max lift & when max valve lift is divided by tappet lift, the magic 1.5 [ or close to it ] is achieved. Ratio is constantly changing.
D. Vizard did a detailed study in his BBC book on numerous rockers & ratios. Fourteen roller rockers, 1.7 nominal ratio [ the number on the box.....] were tested for ratio change. Initial ratio varied from 1.150 to 1.73. Overall ratio varied from 1.536 to 1.79.
 
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