As the title says using a adjustable pushrod. I have some AFR heads comming so like to learn this before they get here, thanks.

 

For starters, you'll have to get a solid lifter that is the same height as one of your hyds. And a set of light pressure checking springs is a good thing too. And you can make your own adjustable pushrod from an old pushrod that's still in nice shape. By cutting it in half and brazing or epoxying a piece of all thread (5mm worked for me) in the hole.
You can get the checking springs at the hardware store.

Then you do a mock assy of your block w the heads assembled using the checking springs, solid lifter, and adj pushrod.

Comp Cams has a tech article explaining rocker geometry, but most guys who know will tell you that's wrong. (unless they've changed it since the last time I looked)

Basically @ slightly over 50% lift, An imaginary line that goes through the CL of the rocker pivot and the CL of the roller tip should be perpendicular to the valve stem.
That's the way that you get the most lift and the greatest efficiency out of your valvetrain geometry.
There's a measurable increase in lift, using that method opposed to the method of simply centering thr roller tip on the valve stem.

It's called the Mid-Lift Plus method, and it's THE way to get it correct.
If you center the roller tip on the stem and measure your lift, then measure the lift using the mid lift plus method, you will see that by using the centering method, you're cheating yourself out of a significant amount of lift.

Visual aids are helpful here, and I have none. But maybe someone else will.

 

I heard of people taking the guts out of the hydraulic roller lifter and using washers or a cut bolt to give the same effect as using a solid lifter. I'am wondering though since the solid lifter don't account for preload wouldn't that give you a false reading? I'am thinking of gutting one of my lifters and using washers but adding in a preload of say .030 or what ever 1/2 turn will give me but not totally sure it that's the right way.

I'll have to look up this Mid-Lift Plus method, I wouldn't mind more lift.

 

The whole purpose for "checking springs" is that they are light enough in tension not to compress the plunger on a hyd. lifter. Just got done doing this when I installed a retro roller cam in mine, and I didn't need any solid lifters.

Do a search under my name and I think I have a post w/pics of the checking springs and adjustable pushrod checker.

BTW- The adjustable pushrod checker will have instructions on how to use it...

 

I Agree the the "Mid-Lift plus" Method is the most efficient use of the rockers geometry. I disagree that you can get more lift by shifting the tip of the rocker on the tip of the valve.

The Mid lift method centers the tip of the rocker on the center of the valve at the middle or center of the lift arc created by the rocker. If you simply centered the rocker when the valve is closed you might come off the valve stem at full lift, especially in a high lift cam / high ratio rocker scenario.

Please correct me if im wrong, but lift is determined by the cam lobe and rocker ratio. If the lobe moves the lifter .300 and you have 1.5 rockers the valve will move .450 inches. In theory the pushrod could be as long as a baseball bat, and the valve will only move as far as the cam pushes it.....

 

As I mentioned earlier, it's difficult to explain without a visual aid.
But the further away the valve stem tip gets from being perpendicular to the rocker arm fulcrum, the less travel there will be along that tangent to the arc.
I think that's the correct terminology for explaining it geometrically.

I had a hard time believing it til I actually measured it using a mock assembly on an actual engine.
Try it yourself and you'll see, then there will be no more debate.
When the valve stem is perpendicular to a line that goes through the axis of the roller tip and the rocker arm fulcrum, at 50% lift, then the valve will have the greatest amount of lift.
Mid lift + became the accepted way to do it because the rocker is most efficient at the point where it's perpendicular. And the valve spring is compressed more tightly as the lift is increased, therefore engineers determined that to have the point where it's perp being slightly past mid lift to be advantageous.
Try it yourself, measuring the max lift with a dial indicator, and find out.
Pushrods are usually available in .050" increments. To err on the plus side of mid lift is the way that has been accepted as being best. Unless you happen to be a fan of less lift.

With the mid lift method, the alignment of the roller tip in relation to the center of the valve stem tip is irrelevant. It's all the angle of the fulcrum and rollertip centerlines in relation to the valve stem angle.

 

Thanks for the clarification. I will have to take a look next time im setting up a set of heads. Im glad i was doing it the right way, If even for the wrong reason....