[pontiacmark]

Finishing up my first real build with my budget 461 stroker and wanted to check pushrod length. I have a HFT cam with stamped rockers. Using the Trick Flow pushrod length checker I tightened the polylock nut nearly all the way down and then adjusted the pushrod until I got the pattern in the attached picture with complete rotation of the cam. I came up with 9.250" with zero lash. Do I still need to add the 0.050" lash and order a 9.300" length pushrod? Having brain fade at this point....

[Gach]

That’s perfect yes I’d go with the 9.250.

[Cliff R]

If you are checking it with hydraulic lifters the plungers are bottomed out when you tighten down the lock-nuts unless you shimmed them up internally. This means the pushrods are too long, not too short. I'd subtract .050" from the measurement and order them at 9.200". This will allow you do adjust the rocker arms down so the plungers are .around .050" from bottoming out in the lifters which isn't a bad place to be........

[pontiacmark]

OK, I may need to redo my measurement. So, when setting this up, I had the cam rotated so the lifter was on the cam's base circle. I then took up the play in the pushrod length with the polylock nut but did not compress the lifter plunger. After that, I rotated the camshaft completely around. As I rotated, the pushrod depressed the plunger in the lifter. The plunger came back up after the lifter came back around to the base circle. So based on what Cliff is saying, I may or may not be too long. Too long could potentially bottom out the plunger in the lifter. So a better method would be a solid lifter with the same height and then add 0.050" to length of pushrod OR shim a hydraulic lifter and not let the plunger depress and then add 0.050", correct? That way you set the length of the pushrod for about 0.050" preload on the plunger. Does this sound right?

[Gach]

The way you originally did it is fine and go with the 9.250 push rod length. If you ran the cam around then came up on base circle. And had same push rod adjustment. Then your good. Heres a thought once you get the play out on hydraulic lifters you go a quarter turn to set the per load. So your all ready going down that .50. Even if you went with a 9.200 push rod you’ll be fine. It’s kind of hard to understand it unless you understand how it all works. Some adjustments require a quarter of turn once the play is out or a have turn. I’m not really sure. On setting hydraulic lifters. Been a while since I’ve done them.

[Gach]

So what Cliff was saying, is if you used a solid lifter, or made the one your using solid. Then its acting like your hydraulic lifter thats pump up, and not one that bleeds down. Which would throw your push rod length off. So with that 1/4 turn that’s basically your .50. So 9.250 might throw it off so the 9.200 would be fine. Sorry hope I didn’t confuse you.

I was just thinking if you went around and back onto to base circle. And adjustment didn’t change then that lifter was pump up like a solid lifter.

[Cliff R]

"So, when setting this up, I had the cam rotated so the lifter was on the cam's base circle. I then took up the play in the pushrod length with the polylock nut but did not compress the lifter plunger. After that, I rotated the camshaft completely around. As I rotated, the pushrod depressed the plunger in the lifter"

It takes about 120 seconds to fully compress the plunger to the bottom of the lifter bore and that's if they have oil in them.

What you want to do is to get the lifter on the base circle of the cam, slowly tighten down the lock nuts. Go to "zero" lash then keep going till they just bottom out the plungers.

Now rotate the engine tur a few times and look at your pattern on the valve.

Keep adjusting the pushrod for the NARRWEST pattern and closest to center of the valve.

Measure the pushrod length at this point.

That is the TOTAL distance with the plungers bottomed out.

Order the pushrods at the next shortest size and you'll be as close as possible allowing some running room for the plungers to be deep in the lifters but not bottomed out. Most lifters these days are petty short travel anyhow, at least the good ones.

This isn't a fussy thing, but for sure you want to transfer the MAXIMUM amount of movement from the cam lobe to the valve AND minimum side-loading at the same time. It''s pretty much the LAST thing done in a professional engine build and requires close attention to detail. I'd add here that there is no "standard" with these things, and hasn't been for decades. There are simply too many variables involved, which include valve length, cam base circle diameter, lifter height, decking/squaring blocks, milling heads, rocker arms being used, (yes they are NOT made to the same standards/specifications as factory stamped steel parts), and now often aftermarket cylinder heads.

For these reasons it's worth the time/effort in this area to make sure you get the most power and longest life from your new engine build.......FWIW......

[pontiacmark]

Cliff, that method makes perfect sense. Since these are new, out of the box Hylift Johnson lifters with no oil, I will do this.
1. Put lifter on base circle
2. Tighten nut down on rocker until plunger is full compressed.
3. Rotate assembly
4. Check pattern
5. Adjust length as necessary to get middle of valve tip
6. Subtract 0.050" from measured length to order correct pushrod.

[Cliff R]

That will work fine and it's a LOT easier than making a "special" lifter by taking one apart and shimming the plunger up where you wanted it........

[glenn911]

Same steps for a Hydraulic roller?