How do i properly check for pushrod length ?

[1984 t-type]

So i bought the adjustable pushrod length checker from full throttle speed but need to know the exact process for checking for pushrod length so i can order new ones. i have the stock non roller style cam, lifters, and rockers. is there a write up listed somewher on here or can some please explain to me what needs to be done ? thanks

 

[earlbrown]

bolt down the rockers and put a cylinder on the compression stroke (base circle of the cam). Unscrew the pushrod until all the slack is taken away and note the length. Take that number and add your desired preload to it.

 

[Jerryl]

COMP Cams® Quick Tech: Achieving Proper Rocker Ar…:

 

[1984 t-type]

how do i determine what my preload should be and how many pounds do i torque the shaft to ?

 

[psycho6cyl]

Great video thx

 

[turbo nasty]

That will video procedure will NOT repeat NOT work with a stock rocker setup up. Our height is set (rocker shafts are where they are) and we don't have poly locks to add or take away preload. The stock setup and lengthening and shortening the push rod wont change a thing on the sweep across the valve tip. You must raise or lower each individual rocker to do that (SBC for example has this if using polylock style setup) to do that. What you are measuring with the stock push rod is simply the preload on the lifter with the rocker shafts bolted down and the cam lobe is on its base circle.

Get the comp push rod length checker and see for your self you can add and take away and all your doing is altering preload the sweep on the face of the valve wont change.

With that said ,I have used shim stock in the past to alter the rocker shaft height to get better valve geometry by raising them. Typically tho its pretty close to center.

 

[1984 t-type]

Ok so now I'm confused again, I have the adjustable checker so how do I use it and how do I determine my preload.

 

[jim0207]

My preload is set at .025. I took one rod to the work bench, closed the rod. Using a .025 gauge I opened the rod until I had .025 between the adjusting nut and the main body of the shaft. Now knowing that this gap was 3/4 to 1 full turn I began to install the rods. All rods were closed. Bring a piston up on compression stroke, open the rod until it hits the rocker. To double check my preload I measured the gap between the adjustment nut and the rod. Now open the rod 3/4 and check the gap. add this gap to the first gap. You should have .025 more to the first number. Adjust accordingly.

 

[earlbrown]

Now I'm confused....



put the pushrod measuring tool in place. Turn it until all the slack is gone. Read the tool. Add .025" to the reading (if you want 25thou), then end, that's it.

 

[1984 t-type]

Ok got that part and appreciate the help but how do I determine how much preload I need, is 25 thousands enough ? Thanks again

 

[S10xGN]

You can check the stroke of your lifters (dry!) using a drill press and dial indicator to find out exactly how much travel they have. Once you know this, set the preload to about 25% of the stoke. For example, if your lifter has 0.100 stroke, 0.025" is what you'd want. This isn't an exact science, but you do want to stay on the low end. If you get the preload too tight, the lifters can "pump up" and hang the valves open.