mattz06

I am thinking about buying a pushrod length checker from summit to be sure everything is just right.

decked shortblock (unsure of deck thickness removed/ surely not much)
afr 205 heads (hopefully someone gets them in soon) unmilled in stock form
crane or comp (NON COMP R'S) lifters

I figure a stock length 7.40 will be right but want to know how to check with the tool?

I am guessing it installs like a pushrod, install rocker arm, tighten rocker to 22ftlbs then remove and see the length?


thanks

BOWTIE

Never seen one for an LS1... Do they offer one now?

felton316

I don't think they will work on an LS1.

rangersix

Mark the top of your valve with a black, non permanent marker. stay within the 7.3"
to 7.4" range as a start point. roll the motor over until that valve fully opens and fully cycles closed then observe the mark. It should be dead center of the valve, if not remark the valve, retorque and adjust the adjustable pushrod length until you find the middle "Rub" mark.
Thats the length you'll need.

BOWTIE

I do not think this will work. It would work if he had an adjustable valvetrain with a solid test lifter and was just looking to maintain the correct rocker geometry, but it will not work with a non-adjustable, hydraulic valvetrain. What he should do, if he has an adjustable pushrod, is make the pushrod too short, then torque the rocker down. Then adjust the adjustable pushrod until you just start to feel the slightest resistance when you rotate it. This would be zero lash. Keep in mind, you will still be able to twist the pushrod, you will just feel a slight resistance because there will be no clearance between the lifter cup and rocker. With out the motor running, the lifter will have a spring that pushes the cup/plunger to the top of the inside of the lifter, this will fairly easily compress unless the motor has run and the cavity underneath has filled up with oil, so it is critical that you stop when you feel the resistance because you can start to compress that spring and you will no longer be at zero lash. Then pull out the adjustable pushrod, measure it, then add whatever our stock lifter preload should be to that. I am not sure what that amount would be. On the old school motors it would be the equivelant of one turn on the adjusting not for a stock lifter and about 1/2 turn on a high performance lifter, and next to nothing extra on a type R lifter. The idea is when the motor is running you want the lifter plunger running about 1/2 way in between the top of the lifter and the bottom of the lifter so it acts somewhat like a shock absorber for the valvetrain. As far as correcting the valvetrain geometry on a non-adjustable valvetrain (centering the rocker arm contact patch on the tip of the valve) the only way I could see doing that would require adjusting the valve stem height, which could only be done properly by figuring out what you needed and then removing the heads, pulling the valves, and butt grinding them to the desired heighth. Hope this helps. By the way, all of this would be done on the base of the cam lobe. Now, can someone tell me again why GM decided to go back to a non-adjustable valvetrain. Anyway, good luck.

BOWTIE

One other thing, this is the reason so many LS1's have lifter noises when the go to a bigger cam, they can not get the preload correct. Even with different pushrod lengths, the best you can hope for is to get it close, because every valve willl be slightly different and the pushrods only come in selected lengths (unless you get a set custom made). That said though, a stock hydraulic lifter can compensate for quite a lot of variance. A type R lifter can not and that is why it is reccomended that you switch to an adjustable valvetrain when using that type of lifter.

strokedls1

iTrader: (1)

You can buy a package of .015 and .030 shims from comp or crane. Put them under the rockers that have too much preload (installed under the rail). I bought an adjustable one from thunder racing over a year ago. I used that to figure out the ballpark length that I was after. Then I used shims to adjust the individual rockers to get proper lifter preload.