Still confused about adjusting hydraulic lifters..

[Terry F.]

Clarification is welcome! So, if working with a standard hydraulic lifter, if you tighten it just untill the play is taken out of the push rod/rocker arm, is that ZERO lash?

If you crank it down 1/2 turn beyond the about point, is that consider a preload?

Sorry to make anyone cringe about this.

I am wondering about the technique of using a standard lifter and adjusting it to just when the play comes out of the rocker (I could totally be misunderstanding this method). My understanding is that it assumes the lifter will completely pump up at high RPM and act essentially as a solid?? I have talked to some people and they seemed to have never heard of such a technique? I also seem to recall reading something about this in my overhaul manual?

Thanks, Terry

[Joe L.]

Re: Still confused about adjusting hydraulic lifte

Terry-----

1) It is as long as the lifter is on the base circle of the cam;

2) Anything beyond "0" lash constitutes depressing the lifter plunger by a certain amount into the lifter body. I have heard it referred to a "pre-load". 1 full turn of the adjusting nut beyond "0" lash will center the lifter plunger in the body;

3) For street applications, I would adjust the lifter plunger by turning the adjusting nut 1/2 to 1 turn beyond "0" lash. I would not try to "get fancy" and do anything else. Factory specification is 1 turn but you may be able to get a little more out of the engine by going with as little as 1/2 turn.

[dave savage]

Re: Still confused about adjusting hydraulic lifte

Here's the way I do it and it seems to work for me(383 stroker)Make sure your cam position is correct-I set the inlet with the exhaust fully open and visa versa.I also fire the thing up just before hand to pump up the lifters.Screw down the adjuster screw by hand 'till the push rod becomes hard to turn with your fingers-this is zero lash.I go 3/4 turn down on the screw and lock it.That's standard proceedure for a small block roller cam motor.If you don't have a roller it may be different.

[Terry F.]

Thanks, Terry *NM*

[Duke W.]

Re: Still confused about adjusting hydraulic lifte

As you turn the rocker nut down the pushrod should have up/down play and the rocker should be loose. Once all the clearance is removed you are at "zero clearance" or "zero lash", all the play will be gone, and you add the preload from this point - say 7/8 turn. Since the OE spec for normal preload is 3/4 to 1 turn, you only have to be within about 1/8 turn of the precise zero lash point to get the final adjustment in the correct range.

With a little practice, you should be able to easily recognize the zero lash point to less than 1/8 turn. Practice on one until you get comfortable with the procedure.

Less "preload" like 1/8 turn should allow a slightly higher valvetrain limiting speed, if that's important to your application, but this little preload may require readjustments over the life of the engine. One turn means that normal wear in the valvetrain and normal valve recession should be compensated over the engine's life, and it's unlikely the valves will have to be adjusted again.

It's important to be on the base circle when this adjustment is performed, which depends on the cam, so what camshaft are you talking about?

Remember that this procedure had to be performed to each and every one of the tens of millions of Chevrolet V-8 engines built from the 50s to 70s, so it ain't rocket science.

It's actually easier to do this adjustment with the lifters empty of oil as they will compress much easier than if they are full of oil. Then if you "prelube" the engine by rotating the oil pump with the proper tool and rotate the engine through at least a couple of revolutions while the pump is spinning, the lifters fill with oil, and the valves will open properly with the first crank, which will get the engine started faster, especially if you have prefilled the carb bowl, set the choke via the normal cold start procedure, and properly static timed the distributor.

Duke

[Terry F.]

Re: Still confused about adjusting hydraulic lifte

What I have come to understand is this. Standard lifters have a tendency to pump up beyond a certain RPM. I don't know what RPM that is, I haven't come across it yet. They can be essentially Zero lashed but with some risks of the lifter flying apart because if not done correctly or not adjusted more frequently, it strains the keeper and the lifter can pop apart. Some standard lifters can be purchased with heavy duty keepers/C-clip vs wire spring thingy. Those with the heavy retainer clip can be zero lashed with less risk.

Then there are anti-pump up lifters desinged to bleed off more oil when operating at higher RPM's when standard lifters start to pump up a bit. These lifters should be adjusted according to the manufacture or like a normal lifters. You should not Zero lash them as far as I understand and if you did they propably wouldn't work right.

Thanks, Terry

[Terry F.]

Re: Still confused about adjusting hydraulic lifte

Thanks Duke! Terry

[Mike McKown]

Re: Still confused about adjusting hydraulic lifte

"My understanding is that it assumes the lifter will completely pump up at high RPM and act essentially as a solid".

You have it almost right. When the lifter is adjusted with zero preload, the plunger in the lifter is already extended as far as it will go and essentially becomes a solid lifter at that point. It won't pump up or extend at high rpm past this point.

When you run the engine at an rpm past the point that the valve spring will keep the lifter pushed down on the base circle of the cam and keep the slack out of the valve train, the lifter plunger (pushed by oil pressure) will try to extend and take up the slack. It can only do this if you have preloaded the lifter during valve adjustment.

When the plunger extends to close the slack caused by valve float, it now will hold the valve partially open when the engine rpm slows and the lifter again follows the cam contour. This can bend valves against the piston and will also cause a loss of engine power until the lifter bleeds off and returns the plunger to normal position within the lifter.

Therefore, the less preload of the lifter you put in your adjustment, the less the lifter can pump up during valve float, the less damage it can cause and also lessen the duration of power loss. Less preload also increases your chances of valve train noise, sooner if not later.

[Terry F.]

Re: Still confused about adjusting hydraulic lifte

Makes a lot of sense... I did not look at it that way. I did not think in terms of the lifter flying off the cam lobe at higher RPM. So, is ZERO lash at all desirable or close to it?? Terry

[Loren L.]

Before this thread explodes into large $$$$$

find a Chevrolet mechanic in your area (through friends, etc.), put the car on a trailer/tow truck and take it to him to have the valve lash set. Pay the bill, say "Thank You" and ask him to explain what HE just did and why.

[Clem Z.]

even so called anti pump up lifters must be

set at "zero" lash and even some anti pump up lifter manufactures recommend setting the lash at .002

[Terry F.]

Re: Before this thread explodes into large $$$$$

No, I have no problem adjusting the valve lash. Maybe one of the easiest things to do and fun if you can keep the mess down. I just am wondering about a few details. Terry

[Terry F.]

Re: even so called anti pump up lifters must be

Interesting. Do you know if chevrolet ever made any special hydraulic lifters, anti-pump up or other wise? Are you saying that some recommended adjusting the lifter like a solid lifter? Sounds as though the lifter was designed to pump up solid?? Can I gain anything by going to any other type of hydraulic lifter other than a standard lifter?? I will use a factory 390 hp camshaft and the heads will be like new. Try not to cringe but I will be using full roler rocker arms (light weight stainless). I just want a solid ride up to 5500 RPM or so. Terry

[Chuck S.]

Re: Before this thread explodes into large $$$$$

Like Duke says, it ain't rocket science...every Helms manual for those years had procedures for making the hydralic lifter adjustment idling (just as messy as adjusting solid lifters), or as Duke described, by rotating the crank to get the intake and exhaust valves in the correct position (can't be done at one crank position).

I read the manual and adjusted my new Chevy myself after it developed a hollow knock that scared heck out of me...I was barely twenty something at the time, so it's not like you have to be a gearhead genius.

[Terry F.]

Re: Before this thread explodes into large $$$$$

Standard adjustment is no problem with standard lifters. I have done it before, couple dozen times. But, I am trying to learn something else. There are other ways to set the lifters so to get the most out of the valve train at higher RPM's. I am trying to get a feel for how un-orthodox this is or isn't. It all might be useless to me anyway since I sort of dought my engine will see 6000 RPM's but I would like to build it to handle it. If there is newer or better technology out there that will help the valve train achieve this safely and without stressing something beyond designed tolerances, I might be interested. Terry