Paul94Z

I've done so much digging on proper techniques to adjust valves on SBCs.. and both the engine running method and adjusting them with the engine off is subjective to human error in looking for the zero lash point.. so that leaves us "the people that don't do it everyday" up for allot of error in judgment for the zero lash point. I see two common problems in the procedures and want to come up with a fool proof method. One, adjusting the valves with the engine running and listening to the "clack" can be hard.. especially when some of your other valves may be loose and making noise.. so that can be difficult to pinpoint. The other problem is rolling the pushrod in your fingers feeling for zero lash.. well this can be misleading because sometimes the pushrod will roll even after starting to compress the lifter plunger "usually what happens in my case" just because I don't have the right feel for it. Here is my idea for the fool proof method: first of all feelers don't lie and math doesn't lie "if done correctly". With a 3/8-24 stud simple math will tell you that one turn equals .041 inch... "1/24". Now if I wanted to get the OE lifter preload of .020 inches it should be as simple as adjusting until you can run a .020 feeler between the rocker and stem and then make one full turn and you will have exactly .021 preload on the lifter. Wouldn't this be the most exact way to adjust them and take any human judgment error out of the process? Any ideas or concerns?

ejfagala

Or use a dial indicator

Paul94Z

even with a dial indicator.. how do you go about establishing zero lash?

Evil Eric

wow, i cant wait to get into this when i put my roller rockers in with my cam next week.

Eff

You got a lot more to worry about than adjusting the valves.

As for zero lash. Someone correct me if I'm wrong, but If you're setting your valves to zero lash, you will hear a valve clatter in a camaro. Hydraulic lifters have to be preloaded. Shoebox has a tutorial on his website, it tells how much to preload it.

442olds

get poly locks, its so simple. Just trun till you feel resitanceon the poly lock, that's zero ( and yes you can continue to turn the poly lock after it starts to compress the lifter but when you get to that point you will definitely know you aren't just taking up the slack). then give it 1/4 to 1/2 turn. then tighten the little set screw in the poly lock. Adjusting valves isn't rocket sicence. Even Comp Cams gives a pretty large tolerance for the lifter preload condition.

97 6SPEED Z

Well, the method you describe may work (???), but since I've always adjusted my rockers with the engine idleing and had a pretty easy time of it, I'll offer you one hint on how to make the job easier: When you get the engine idleing and the oil up to temperature, just tighter all the rockers untill they stop "clacking", and then back off and re-adjust each rocker in turn until all 16 are done. This way you don't have any "competing" rockers "clacking away" while you're adjusting one at a time, and it makes finding "zero lash" really easy.

And yes, hint number two would be to never "rev" the motor with those valve covers off, unless you really want(???) that "hot oil" treatment.

Mikey97Z

You're right about calculating the threads, but you can't use the feeler like that. You have to start with zero slack, then add preload. You can't put the feeler on the valvestem ... the rocker has to be in contact with it. Once you have NO SLACK (the pushrod gets a little resistance to it when the slack is gone) then you add .020 preload to it by going an additional 1/2 turn to depress the plunger .020"

whatsup

I installed my cam last Spring and used the method on Shoebox's site. Turning crank 1/4 of a revolution and ajusting the valves at TDC. Yes it's a "feel" thing. This was my first time working on a LT1 and had no issues at all.....worked to perfection. In the years past ( many ) I always used the running method and did as stated above....tighten all of them down to get all noise eliminated and then start adjusting from there. That also always worked with no problem. When they built these cars in the factory do you think they had someone adjusting eack one...NO!!! Its a assembly line and there is a setting, ( saw it some where once but don't remember where ), X amount of turns and that's it.

ejfagala

You use a piece of a coat hanger to extend the dial indictor and set the tip on the lifter next to the push rod and set the preload on the indicator. Now that you have a zero point as soon as it starts to move you have zero lash and you can set your preload to waht ever spec you like with exact results. I use this method when I build a motor and set the lash cold.

MentalCaseOne

Guys I got a new one for you... I am holding a brand new Scorpion Roller Rocker in my hand right now and I am looking at the area where the Pushrod makes contact with it. Well Its not smooth... Its got lots of markings from the manufacturing process and its consistent with all the other brand new roller rockers in the box they look like tiny round grooves on it. I can count at least 12 of them. very small.

You guys know what that means? as soon as the pushrod makes contact with those markings on the metal it will begin to either compress them or wear them out till its nice and smooth as it did on the old stamped rockers I just removed from my car. It may not seem as much but I guarantee you it will remove some of the pre-load on the lifters.

Honestly I would not be surprised if I have to re-adjust my RR's a couple of times if not more, depending of how long I wait in between adjustments. Those little ridges will smooth out taking some of the preload out.


Marvin

MentalCaseOne

Update... Installed Scorpions with Beehive Springs.. Adjusted all the rollers to 1/4 turn preload.. double checked them.. Turned the car on and in only a few seconds they all were clacking.. the poly locks were solid but somehow the rollers loosened up. I readjusted 4 of the biggest offenders.. now there is a lot less clacking than before.. almost gone if you ask me. I will readjust all of them once again.

Point being is.. the poly locks did not get loose. something else gave way. The clacking its almost gone now but I wanna reset the zero lash and do a 1/2 to 3/4 turn on the new OEM lifters again. The book say "one full turn" and all the posts I have read people are doing 1/4 to 1/2 turn...

I know the compcams lifters use very little pre-load but I am using new OEM lifters.. should I go one full turn? I changed the Studs to 7/16 ones and they have a 20 thread count... I believe is not as fine as the 3/8's I removed... should I stay at 3/4 preload?

I please let me know what do you guys think.


Marvin

1racerdude

The thing is to tighten all down before you start real adjustment. You can tell witch ones with your thumb.
The rest is pretty basic,but some people can't get it.
When doing the spin method it is the difference in pressure to turn you are looking for.
1/8-1/4 turn ha been used for years with good results,so use it and don't try to make it a mystery.

Practice,Practice,Practice

shoebox

Everyone makes it out to be so complicated. It's not. Consistency is what you want, no matter what method you use. You can then use that as a baseline to make more adjustments if you are not pleased. The preload method of adjustment of hydraulic lifters has been around since they were invented. No, one preload setting is correct for all types of lifters (as evidenced by stock vs. Comp R's).

I have used method 1 on my site for most of my hydraulic lifter setting. It seems to work perfectly every time.

LameRandomName

I dunno about that, but it would for damn sure take out any chance for you to "feel" when it's "right".