Mostly just a rant but also a warning/education for those thinking of adjusting valve lash.

I got some 1.6 rocker arms to put on my L03 in hopes of raising the run-out-of-power point above the stock 3000 RPM. If you're curious, it did NOT make a SOTP difference. <sigh> probably will help once I've done intake exhaust etc.

At any rate, Chilton's has directions for setting the valve lash with the engine stopped and with it running. My friend and I knew how to set it running, adjust until it ticks, then just til it doesn't, then tighten 1/4 turn. Chilton's said tighten 1 full turn... I think that's too much. But we figured we'd give the engine stopped adjustment a try, see how accurate it was.

The directions said turn the motor to TDC compression stroke, then we could tighten half the valves, then turn it to TDC exhaust stroke and tighten the other half. That part is fine. However it says tighten to 0 lash (cant spin the pushrod with your fingers any more is the test we used) then tighten 1.5 turns from there. WOW. We figured that was too tight, we'd only tighten 1 full turn from 0 lash.

CHILTONS IS WRONG.

Thank *** I've got a roller cam. Had that been a flat tappet we probably would have wiped some cam lobes. It was THAT overtight. Luckily we decided to run it before putting the valve covers on just to make sure of the adjustment.

The first time I went to start it, the starter made a horrible screaming noise, and the engine wouldn't turn over. Not a good sign. We decided to loosen the rockers 1/4 turn.

The second time I tried to start it, the starter made a slightly less horrible scream, the engine turned over once or twice then backfired. As near as we could tell the rockers were so tight that the valves were hanging open. We loosened another 1/4 turn.

The third time I started it, no more horrible screams from the starter, but the engine ran like crap. We're guessing most of the lifters were probably collapsed. Loosen another 1/4 turn.

The FOURTH time I started it, the engine ran more normally. However about half the rocker arms weren't oiling well and some weren't oiling at all.

Now I adjusted them the correct way, turn until they tick, then don't tick (making sure to allow time for lifter pump-up), then 1/4 turn more. The majority of them had STILL been too tight. Once they were adjusted correctly, all rockers oiled well, and the same amount. And the engine ran much better.

So the lesson here is, if you want to approximately set valve lash with the engine not running, turn JUST to 0 lash and NO TIGHTER!!!

The scary part is that we just a month ago or so finished a flat tappet cam swap on another friend's car... we left the rockers very loose and adjusted once the engine was running. Had we tried this method on his car we could have ruined his cam and possibly killed his engine (cam lobe bits on the crank bearings = bad).

 

Could that also be because Chilton's instructions are for the stock stamped 1.5 rockers? Maybe by changing the ratio you have to set lash differently or something? When I got my new cam I just followed the instructions w/ the cam and they said to do it with the engine running, and I think 1 1/2 turns after 0 lash. My setups been fine for a few months already.

 

Hmm, interesting point.

I would be suprised if that completely caused this. The difference in lift at the rocker tip is only 7% or so (1.6/1.5, 6.666% actually) and they were a lot more than 7% too tight. The problem was that at 0 lift the valves were still open. 0 lift times 1.5 is the same as 0 lift times 1.6. So the arms were tightened to the point where with the cam at 0 lift, the rocker was pressing the valve open. The 1.6 rockers would be opening the valve 7% more than the 1.5 rockers, but the point is NEITHER should be opening the valve when the cam is at 0 lift.

I'm suprised that your cam said 1.5 turns after 0 lash, by 0 lash do you mean no lifter ticking? Almost everyone on here recommends between 1/4 and 1/2 turn after the lifters stop ticking.

 

When I said the instructions said to turn the rocker nut 1.5 turns after 0 lash was with the engine off (the way you mentioned in your first post... only they said 0 lash is when there is 0 clearance between the rocker and the valve I believe.) They said in big bold letters not to pump the lifters, which I believe is what you are doing when you set the lash with the engine running. I don't understand this whole topic 100% but maybe somebody can clarify it? Just tryin' to learn

 

None of the above?

Its been my experience that people cant find 0 lash correctly by the spin the pushrod method, especially with new lifters. To get the plunger off the upper seat in the lifter doesnt take a whole lot when theres little to no oil or the new from factory super thin machine oil in them. I'd guess you had them well past 0 lash before you even went to tighten them down.

 

Are you using aftermarket nuts with locking screws or the stock type locknuts? It has been my experience that it is REALLY hard to tell when you are at zero lash with the stock nuts, and very easy to tell even without spinning the push rods when you get to zero lash with the aftermarket type. Have done a LOT of adjustments with aftermarket rockers and nut/lock screws and never had any trouble with zero lash and then 1 to 1.5 turns down.

 

I just got done with a cam swap on my van and that's EXACTLY what I thought.

I've never installed a set of roller rockers before, only stamped rockers. With the roller rockers you can set the rocker down on the pushrod/valve tip, then put the rocker nut on just so it barely touches the rocker fulcrum. That is ZERO lash. Since I don't have a high revving engine I did a 1/2 turn past zero.

With stock rockers the nut is meant to jamb so to turn it you need a wrench, and that takes away from the "feel" of finding zero lash.

 

You should only tighten the rocker until you feel resistance turning the pushrod. Not until you cant turn it, thats way too tight. Also with aftermarket cams you really should adjust the valves for each cylinder when that cylinder is at top dead center. Adjusting half at a time with an aftermarket longer duration cam, can mean that some of the lifters arent sitting on the base circle. There is approximately 2 turns of travel in a lifter. If you get anywhere within those 2 turns the car will run allright. The old standard was to center the plunger in the lifter, which meant 1 turn past 0. Everybodys learned since then that if you only set it 1/4 to 1/2 turn you'll save gas and gain power. If you look at old books they start at 1 turn and the newer you get the less the spec becomes. I've got some books that say 3/4, then they say 1/2 and now 1/4.

 

The best thing that works for me is to adjust the valves with the motor not running. I go half turn past zero lash just to get in the ballpark. Then I start it up and redo the final lash adjustment as Eggplant described (back off till it ticks, tighten til it stops, the a quarter turn more). IMO adjusting valves with the motor running is THE best way.

 

Thank you all for the info.

I was indeed using stock type nuts, and you are correct, I did not notice when the rocker contacted the valve since I was using a wrench and it was hard to turn the whole time anyway.

Yeah if I should have just tightened until there was resistance to spinning, I was way past 0 lash :-). I tightened until no matter how hard I tried I could not spin that pushrod using my fingers. If I could spin it even a little, I tightened it more... Yeah they were way too tight.

 

I use the half and half method with the engine not running and have had very good luck with it on even longer duration cams (like 230 and 240ish degrees @ .050). But I agree... The trick is to properly find 0 lash and not overtighten them. 1/2 turn is all you really need - maybe just a touch more to be safe, but definately not 1 full turn! I usually use the pushrod turning method to find 0 lash and go until they won't spin freely and then take them to 1/2 turn past. If I can't get an accurate 'reading' from turning the pushrod, I just tighten the polylock with my fingers until I feel a tiny bit of resistence (ya gotta kind of go up and down with it a few times to really 'feel' where 0 lash is) and go 1/2 turn past and lock it down. That works very well for me. Stock style jamb nuts make it a bit harder since they have resistence built into them, but you should still be able to use the pushrod turning method.

I have found that going back and doing them again (even with hydraulics) with the engine at operating temp works even better as you can really feel when you get to 0 lash that way and all of the clearances are where they are going to be with the engine running.

 

I use the not running method. I adjust the lifters when doing the assembly, with the intake OFF. I use a .002 feeler gauge and go 5/8 turn past, 1 cyc. at a time. Maybe slower this way, but it works. After break in I do it the feeler gauge method again. But I was broke in adjusting mechanical lifters back in the late 60s. I don't go do it with the engine running because of the mess, even with the little plugs you can buy.

 

I ruined a brand new cam, lifters and starter following the Chilton's instructions!

Now I've got a slight ticking in one of the roller tip rockers, but am a little nervous about overtightening it again!

 

all i gotta say is get a haynes. i changed the valve stem seals in my LO3with my dad and he read me the instrustions while i adjusted them and they cam out complety perfect and i am only 16 so chilton must really suck. i am to afraid to do the car running method. with my luck i would drop a socket on a rocker and them oil would squirt me in the eye and i would get shot in the head with the socket. lol thats just my luck. well i am builden a 350 right now with a 230 duration cam and i planed on useing the engine off method. do u still think its safe with that cam? thanks

 

The engine off method always worked for me but for gods sake only adjust the valves when the oposing valve on the same cylinder is at full lift. If you use the half and half methode on anything other than a stock cam or if your timing mark is a degree off you won't be on the base cirlcle of the cam. Ate a cam and wiped out every bearing in the motor because of this. damn manuals

 

Always did the engine running trick. Mom made me push the car out of the garage after a smoked up the house though. I was hustling because i didnt have any thing catching the oil. That will keep you hopping.

 

Well.... actually, with a 'bigger' cam, it wouldn't make sense to do all of the valves when the other valve for that cylinder as at full lift. That method should work well for doing the exhaust rocker when the intake is at full lift, but when you do the intake rocker with the exhaust rocker at full lift, you may run the chance of not being anywhere near the base circle of the intake lobe as the intake valve may begin to open when the exhaust valve is still open (pretty much garunteed with a 'big' cam). If you do it at full lift you should be still be OK, but I wouldn't chance it. If you feel the need to do them one at a time like that, you can do the exhaust rocker with the intake at full lift like mentioned above, and do the intake when the exhaust rocker just starts to open. That way you will be much more likely to be on the base circle for that intake lobe (or at least not running the chance of being as near to the ramp of the intake lobe that way).

Laterzzzzz,
Matt

 

I have used the TDC, 360 from TDC method several times and it has always worked. In fact, this is the same procedure that is in the Helms shop manual. Maybe you misunderstood the directions? You adjust specific valves at TDC, rotate 360 and then adjust the rest. Piece of cake and has always worked great when not considering all out performance and high RPM power.

I agree that the best way is with the engine running - but the method above gives you a really good starting point.

Another way is to simply turn the engine by hand (with a breaker bar, etc) and watch the pushrods. If the pushrods are not moving then you are on the base circle of the cam and can adjust that cylinder. I would recommend about 1/2 turn for a daily driver and as little as possible for the most power.

Tim

 

using the TDC/360 method, which valves do you adjust when?

please list in terms of

TDC----
intake: #1,3,5
exhaust: #143

360----
intake: #6754
exhaust: #6386

thanks :hail:

 

I've tried the 'turn till you feel resistance' method, but it's very difficult when there's oil all over everything.

Instead of turnin them, I jiggle them like Matt87GTA said. Once they stop jiggling, 1/4 to 1/2 turn. That's all.

And the easy method is IC/EO. When the intake is closing, adjust the exhaust. When the ehxaust is just starting to open, adjust the intake. It's much easier (no offense) than trying to find peek lift without a dial indicator.

 

I don't dare adjust without the engine running. Get some of those little metal clips summit and jegs sells to keep the oil from splashing and start the motor. Loosen until an audible clicking/ticking noise. Tighten 1/4, 1/2, full turn, whatever floats your boat. I always just turn 1/2 out of habit. The only time I'd adjust lash with the motor off is when other parts are missing from assembly and preventing me from running the motor.

 

For my rocker change it was a simple job(a little messy though), just went to 0 lash (get some resistance with the pushrod while spinning it). After I started the engine, heard ticking, tightened till it went away then gave an extra half turn. Even those that weren't ticking I backed them off till they ticked and then repeated. 20000 miles later and still running strong. i gained 2 tenths in the 1/4 mile too after putting them in and 3 mph.

 

To bring back an old post, I just want to confirm that for the engine off method, 1/4 to 1/2 turn past zero lash is the way to go, correct? And 1 to 1.5 turns is just downright bad news? My rockers have been making noise sinec I built the motor, and have heard so many conflicting methods it's scary, I'm now nervous after hearing people talk about grenading cams and up to engines with the 1.5 turns after zero lash - mine are set at about 1 or 1.25 and am PRETTY nervous that I have to drive home before I can adjust them (what's worse is that they've been set there for a little while - not long, but too long for comfort). I look forward to giving the 1/2 turn a whirl - assuming that's the general reccomendation of the trusty board

Thanks guys

 

That's funny, my chiltons doesn't say that. When did you get yours?

 

i say forget hydraulic and go solid cam

as for hydraulics adjustment method , i agree with slade1 and jprevost .

 

WOO HOO!!! 1/2 turn past 0 lash is the SHIZZZZZZ!!! No more clatter, and it runs quite nice!

 

I have a question for you guys... I adjusted my roller rockers on my 350 with the engine out of the car and no intake. I used the method that came with the roller rockers. No that the engine is in the car and all installed. I get a tick out of them. The engine runs fine, a little stumble on idle, but as soon a i put it into gear, i get a loud backfire and if i accelerate, it is a pig. and it backfire a hell of a lot under load. Could this be because my rockers aren't adjusted correctly? Just a little background, i swap a 305 for 350 into my 86 Iroc, Still using stock 305 chip, and i plan on rebuilding the stock HEI (new module, cap, rotor etc.) So could the cause of the backfire under load be due to incorrect valve lash? I appreciate your help

Thanks Jon:hail:

 

I adjusted mine how Comp recommended in the instructions for the rocker arms. 1:5 or 1:6 ratio shouldn't matter at all. This is with Comps magnum 1:6 rollertips and an XE274 cam.

Turn the engine over by hand in the direction it runs until the exhaust pushrod begins to move upward and opens the exhaust valve. You can now adjust the intake valve of that same cylinder and be assured that you are on the 'base circle' of the intake lobe.

Tighten the adjusting nut until all the slack is taken out of the rocker arm and pushrod. By lightly turning the pushrod with your fingers as you tighten the adjusting nut, you will discover of feel a point at which there will be slight resistance. At this point you have taken all of the excess slack out of the pushrod and are at 'zero lash'. Turn the adjusting nut one half turn more.

To adjust the exhaust valves , turn the engine over until the intake pushrod moves all of the way up. Rotate past maximun lift, approximately one-half to two-thirds of the wayback down. You are now on the base circle of the exhaust lobe and can adjust the exhaust valve.

I followed this and have had no problems. I had planned on readjusting them with it running but these Comp rockers are a little more narrow inside and the socket likes to get stuck. This is with a thin walled 5/8 12 point socket. I need to ask the Snap On guy about a really thin walled socket before I try to adjust them with the engine running

 

I am bulilding a LT1 to put into a 89 camaro. I have the 1.6 roller rockers (self adjusting) i just read all about adjusting them, My question may sound dumb but im gonna ask it. What does the "self adjusting" mean and do I have to adjust them initialy? thanks

 

i thought the reason you tighten em down is to give them .020" preload, and since a full turn represents .080" of thread (12.5tpi) and 1/4 of a turn represents 1/4 of a thread. and mayb other threads have different pitches and thats why ppl have different settings.

even if im wrong(which i prob am), when you guys adjust your lash running, with the valve covers off, do you guys have oil ever spray up from the heads, do you block off certian things? what do you do, id really like to know how to adjust them with the engine running.

 

That's the method I've been using for some time, works very well. Slip the feeler guauge in, set it, lock it and move onto the next one. When I had hydraulic lifters, I'd do the engine running method. Back off till clacking, tighten back up slow till no clacking and then 1/4 turn more.

 

Best way I've found to prevent oil from going everywhere is to find an old set of crappy valve covers and cut a window across it to access the adjustment. Might need to bend a piece out of the way here or there. Test fit first.

I'm not a 100% sure but I think you may only need one for the passenger side. I remember hearing that's the side that drips more.

Last part might not be true but I did cut an old pair of valve covers and it does stop the oil.

 

*Cough* *Cough*

This threads kinda dusty

FWIW, IMO the best way to set the lash with performance cams is to do each valve independantly with the lifter on the base circle of the cam. Takes a little longer, but the engine is off, and theres no mess. Its more precise as well, which is important with some of these aftermarket hydrolic lifters with an anti pump-up design. Mis-set those, and they tick like hell and act like rhoades lifters.