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| JeffK | Valve adjustment question | ||
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Elite Guru
 
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Before I fire this thing up tonight and mess up anything I have a question.
I found a post on CF by Joe C. regarding valve lash adjustment. Using a .015 feeler gage I adjusted the polylocks until it grabbed the feeler then I tightened another 1/2 turn plus the little 1/16th turn to set the polylock. I followed the FSM as far as what valve to adjust when and everything seemed good. The next night some of the rockers had some wiggle to them, nothing huge just very, very slight. Pushrods were still tight, I wasn't able to rotate any of them or anything. Is this normal? or am I going to ruin some stuff if I crank it up? |
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Posted on: 2011/3/9 16:07
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| flyboy | Re: Valve adjustment question | ||
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Gee, I thought I had heard all the valve adjusting methods that are different from what is in the FSM, but this is a new one on me. How much pre-load do you end up with using this method, 1/4 turn?
I had a little side to side (rotational) wiggle on a rocker with 1/2 turn of pre-load, but no up and down movement just like what you said. |
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Posted on: 2011/3/9 16:29
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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Man, there are so many different methods to do this. I went into information overload researching. I think it pretty much ended up at 1/2 turn preload.
Once I tightened it to where it grabbed the feeler the pushrods didn't spin and there was no up-down movement, then go another 1/2 turn. Joe C. post - several years ago, i adjusted the valves in my 85, and had major issues. now, i have adjusted valves for damn near 40 years, but for some reason, the #1 cylinder was giving me fits. three times i adjusted the #1 cylinder too tight, and the thing ran like crap - valves never fully closed. drove me nuts, because i never gave it a thought that the valve adjustment was an issue. seems like the "rotate the pushrod until resistance is felt" was the problem - at least on the #1 cylinder. after giving this a little thought, i readjusted the valves a little different. for the adjusting sequence i pretty much followed the FSM - so with the engine in the #1 firing position, or TDC, adjust the following: exhaust -- 1, 3, 4, 8 intake -- 1, 2, 5, 7 now here's what i did for valve adjustment: using a .0015" feeler gauge, between the rocker arm and valve stem, slowly tighten the adjusting nut until the feeler gauge "grabs". at that point, you should be within .001" of zero lash. then adjust the nut 1/2 turn. this method seems a little more exact, or precise than the "rotate the push rod while turning the adjusting nut" method, and should result in a more even adjustment across the board.. now, rotate the crank 1 revolution or 360 degrees, and adjust the following: exhaust -- 2, 5, 6, 7 intake -- 3, 4, 6, 8 the 85 ran like a champ. several other forum members have used this method with success. give it a try... Hopefully this won't cause any issues because it's posted over there. |
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Posted on: 2011/3/9 16:34
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| flyboy | Re: Valve adjustment question | ||
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Elite Guru
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Well, that would be 1/2 turn less .015", wouldn't it? I think 1 turn of the nut=.040". What that translates to at the pushrod I don't know. Probably = to about a 1/4 turn of preload.
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Posted on: 2011/3/9 16:38
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| flyboy | Re: Valve adjustment question | ||
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Crane says 1/2 to 1 turn, no mention of a feeler gauge. Mine are set at 1/2, everything is good.
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Posted on: 2011/3/9 16:49
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| flyboy | Re: Valve adjustment question | ||
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Elite Guru
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Just read Joe C.'s method. Sounds like a plan. If it was me though, I would probably screw up my feeler gauge reading LOL.
What threw me off, you wrote .015" not .0015". You did use a .0015" GAUGE right? |
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Posted on: 2011/3/9 16:55
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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Ha-ha. I just realized that I might have used a .015" gauge. Guess who's going to be removing valve covers again tonight..
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Posted on: 2011/3/9 17:18
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| flyboy | Re: Valve adjustment question | ||
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While the .0015" method may be more precise, eyeballing the 1/2 turn of preload is sure to vary more than .0015 IMO. Once you get a feel for it, if the nut is turning freely on the stud, you can just spin it down till it stops and call that 0 lash. My problem is mind wander and skipping something so I always do it step by step one at a time and mark it off on a piece of paper.
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Posted on: 2011/3/9 18:57
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| Matatk | Re: Valve adjustment question | ||
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Webmaster
 
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The feeler gauge is an older racers trick I know of. The first time I ever worked on heads on a car that's how I did it, but then we readjusted them while running, too.
The lifters are hydraulic, and probably bled down a little overnight which is why you felt some more wiggle room. Just use the standard method (twisting pushrod in fingers) if you are concerned. Matthew http://www.circletrack.com/enginetech ... ing_valve_lash/index.html http://www.chevelles.com/techref/ftecref17.html |
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Posted on: 2011/3/9 19:06
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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Well, the first couple I did with the gauge I also checked the spin / twist on them too and it seemed to be about the same.
It would be nice not to have to take those valve covers off again since the A/C compressor and bracket have to come off too but I think rather than having something get messed up I will do it just to be safe. |
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Posted on: 2011/3/9 19:18
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| Matatk | Re: Valve adjustment question | ||
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.015 feeler gauge should be correct:
http://www.amazon.com/Lisle-68050-Valve-Feeler-Gauge/dp/B0009OR94M http://www.jegs.com/p/JEGS/JEGS-Feeler-Gauges/751016/10002/-1 |
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Posted on: 2011/3/9 19:23
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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I think I missed a 0 Matthew. I think I used the .015 where the post said to use a .0015
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Posted on: 2011/3/9 19:34
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| Matatk | Re: Valve adjustment question | ||
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Quote:
.0015 is like nothing at all it's so thin. .015 is the correct one. |
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Posted on: 2011/3/9 20:01
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Matatk | Re: Valve adjustment question | ||
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Posted on: 2011/3/9 20:08
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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DUH - Somehow I missed where you had already posted this article Matthew.
Summary - Once you've determined that the valve you are checking is fully closed, actually checking the lash is the easy part. Simply use a feeler gauge and slide the tab of the correct thickness between the tip of the valve stem and the end of the rocker. The camshaft manufacturer or your engine builder will give you the preferred lash range-it's usually between 0.010- and 0.024-inch for a race engine. So let's assume a hot lash spec of 0.017, so you will use the 0.017 tab on the feeler gauge. If the gauge won't fit between the rocker and valve stem tip, loosen up the adjuster nut until it will, then tighten down until the 0.017 tab just fits while a 0.018 tab would be too thick, then tighten down the lock nut. I think I'm good. Thank you Matthew. |
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Posted on: 2011/3/9 20:26
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| flyboy | Re: Valve adjustment question | ||
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Elite Guru
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The circletrack links are about mechanical lifters.
The Hotrodders link... well read a little farther. The reference to the .015 feeler gauge is meaningless. Joe C. used the .0015 feeler gauge to help him get to within .0015 of 0 lash. Just his way of reassuring himself he didn't go past 0 lash. Like I said in post 4, if you put a .015 feeler gauge between the valve stem and the rocker and then cranked 1/2 turn, you probably have the equivalent of 1/4 turn of pre-load. Some guys use a 1/4 turn so you should be O.K. Let me put it one more way and then I'm done. I bet you still had some end play in your pushrod after you removed the .015 gauge and before you gave the nut another 1/2 turn. |
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Posted on: 2011/3/9 21:12
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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In the interest of doing things properly, I am going to take the covers back off and do it the twist way.
Will turning the motor over by hand circulate enough oil to pump the lifters up or do I need to bump it with the starter a couple of times? Engine hasn't been cranked in almost 6 weeks. |
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Posted on: 2011/3/9 21:50
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| flyboy | Re: Valve adjustment question | ||
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Elite Guru
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The internal lifter spring pushes the plunger to the top of it's travel.
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Posted on: 2011/3/9 23:57
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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Yeah. I realized that after I posted it about the lifters.
I'm in the garage now. Got the driver side VC off and readjusted a few. It actually seems like they were at 1/2 already. I'm tempted not to mess with the other side. |
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Posted on: 2011/3/10 0:04
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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I ended up doing both sides. What a pain it is to get that passenger side VC off. I'm really glad that I don't have the EGR tube to contend with.
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Posted on: 2011/3/10 20:27
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| biggrizzly | Re: Valve adjustment question | ||
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2011 Memorial Day Car Show Winner!
 
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Just for the hell of it, I ripped, edited and uploaded a section from a DVD series I own that illustrates the process.
This is from a 3 disk set of the Power Building Videos, Heads, Porting and Valve Trains. This is a great video set to understand what the heck is going on with the heads, cams and timing and valve geometry. Lots of questions answered in that set. |
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Posted on: 2011/3/10 22:05
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| rayquayle | Re: Valve adjustment question | ||
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Senior Guru
 
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Quote:
Gotta love Aaron Johnson.  |
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Posted on: 2011/3/10 22:49
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Ray Quayle in England '86 Indy PaceCar, 4+3 NCM Founder #2896 NCM Lifetime #672 Graduate of Gordon's School |
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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That is awesome Don. I might have to see about getting a copy of those DVD's.
Thank you for posting that! |
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Posted on: 2011/3/10 23:16
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| Weavsvet | Re: Valve adjustment question | ||
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Senior Guru
 
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Quote:
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Posted on: 2011/3/10 23:19
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1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
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| flyboy | Re: Valve adjustment question | ||
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Elite Guru
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I wish he would have explained how much torque he put on the lock down screw. Didn't look like much. I have read so many posts about guys complaining that their rockers loosened up on them so I cranked mine down till they "chirped". I have had them off once or twice and never had an issue.
He demonstrates yet another method of determining when the valves are on the base circle of the cam. He is adjusting the intake and exhaust valve of the same cylinder at the same time using terms like "about a 1/4 turn." Nice vid. but I think I'll stick with the factory method where the crankshaft is turned to an exact position. |
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Posted on: 2011/3/10 23:49
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| JeffK | Re: Valve adjustment question | ||
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Elite Guru
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Fired it up last night. No scary noises from under the valve covers.
Thank you guys for all your help and advice. Can't wait to drive it. |
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Posted on: 2011/3/11 12:52
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