The Stovebolt Site Forums The Shop Area Engine Shop Checking valve clearance while running?

I met a retired GM mechanic-now 83 years old-who told me that they used to crank the idle down way low on 216/235's and check clearance while running and then set only the offending valve or valves instead of going thru the entire set. Sounds logical? Anyone else heard of that method?

If you can hold the feeler gauge steady while the engine is running, it would work. But the valve is going up and down so how you stay on the valve tip is going to be the trick. If its hydraulic lifters, then yes, its a very easy way to adjust them, but mechanical or solid lifters, not so much.

Joe

I could, and did it, several times back when I had the '50 and was a lot younger. Now I shake more than the rockers! First time I ever I saw it done like that was my daddy back when I was a little lad.

That is the way I was taught to do it when I was a boy.

If they are mechanical/sold lifters, I now do the "static method" as described in the Stovebolt.com Tech Tip and here.

I'm 71 and the only way I have ever adjusted them after the initial adjustment is with the motor running. I do my GMCs and my Y-Blocks that way. It's not that hard to develop a feel for when they are right. I figure thats why they call them a feeler gauge.

I'm with you guys, pop taught me to adjust them running and
that's the way I like to do it. Although I have done them
using the static adjustment at times, especially on the first
go round after re-installation.
I personally feel that unless you'r super fast, with the
engine off the valve train cools down enough to give you
inaccurate clearances by the time you hit the last rocker.
With the engine running they all are stabilized at the
operating temperature.
The challenge is to 'feel' when the .007" or .014" gauge just
slips when the lifter comes off the ramp. The clearance may
change after you lock down the screw so you might have to hit
the adjustment a couple of times before you nail it. Like
anything else, you get better at judging how much take up
there is in the lock nut if you adjust valves often.
One thing to note here, is the feelers can get hammered
thinner if they are well used giving you false reading.
Just think of the valve train as a mini drop forge which
over time will hammer out the feeler blades. It's usually
quite obvious when a feeler gets thinned out, but a
ball mic will tell the truth.
Denny Graham
Sandwich, IL

If you are fast enough with the static method, might the engine/head temperature increase while doing the adjustments (heat soak)?

Even though I prefer the safer/easier static method, I have/use a few of these valve-lash adjustment tools to assist if I ever go back to the engine-running method.

I like the static method now, seems safer. Back in the day I was taught to adjust the valves with the engine running, and the 'feel' of the blade between rocker and valve was like a knife through peanut butter.

Those adjuster tools work well on a static adjustment too- - - -sort of a "third hand". I can adjust all 12 valves in about 5 minutes by using the "companion cylinder" static adjustment procedure.
Jerry

Doing it on a running engine is super easy with the valve tool. Get the right feeler and try to insert it on the stem. If its to tight the feeler will not slip in, if its to loose it will.

With the feeler in on the stem you are at zero lash.. not a huge deal, so just use the handy valve tool to both adjust the lash so the feeler goes in freely and then tighten the bolt.

The tools come up on ebay for about $30. Some are double ended, others just single ended.

I bought one on ebay-double ended- and it really helps. Seems like I paid $30.00 for it.

When given a choice between a half-donkey running adjustment or a good one with a warmed-up, stopped engine, I'll choose the stopped procedure every time.
Jerry

I have done this many times. It is easier with the lower fenders on my 52 than it is on my friends 57. Turn the idle down, as low as it will run. If you get one too tight it will miss. You will know right away. Mechanical lifters are easy. Hydraulics can pump down with low oil pressure and make you nuts. Static works as well. There is always more than one way to skin the cat as it were. I tend to set them loose static on a clod newly disturbed engine. I don't worry if it clatters for a bit. When it is warm, and tuned. Then I like to adjust to make it quiet as I can and still have clearance. Nothing will burn an ex-valve faster than too tight. To get it "by the book" Hotrod has it about right.

I use an old Snap on tool that holds a 1/2" drive socket for the lock nut and has a screw driver bit to turn the adjustment. There must have been millions of them made because there are always a dozen or so on eBay. I don't think I ever had a blade to get beat to where it wasn't accurate any more. And all I ever used was the .012 and .020 for GMC and the .019 for Y-Blocks. Of course maybe I lost them before they got bad. I don't worry about clatter, but I do worry about too tight. I have found most of the clatter can be eliminated by touching up the rocker on my old Sioux valve machine. When the rockers are beat out in the middle, you get a false reading.

If somebody insists on doing a running clearance check for some reason, at least try to find one of the Snap-On GO/NOGO feeler gauges with a .002" step-up about 1/2" behind the tip of the feeler gauge blade, for instance .010"-.012" on the same blade. Those gauges were designed to simplify valve adjustments, as it's easy to tell when the adjustment is right.
Jerry

Since my TM specifically calls for the motor to be running and the use of the special tool I don't think that's its any more or less accurate than stopping the motor. Feel free to check my 235 when you see it and if its off, I'll buy you a warm diet soda.

What is funny is that people think that valve adjustment is some sort of microscopic adjustment done to the outer electron shell of the molecules making up the steel valve stem.

Adjusting the motor cold and counting nut flats is just as good as a feeler gauge. Or even better... if it taps to loud its to lose, if it backfires its to tight.

Its a lash setting.... think along the lines of horseshoes and hand grenades.

Thanks for those links, Tim. It really helps in a thread when researching. Here's text info from the links:

Autozone Go-No-Go Feeler Gauge
Part Number: 25024 Alternate Part Number: 222
$7.99

Lisle Go-No-Go Feeler Gauge(on Amazon)
Item model number 68150
$10.96

Snap-on Gauge, Feeler, Step Blade
Part number FB322
$17.30 msrp (and their website is down/getting updates)

Brad

Its true the adjustment is not like building a rocket, yet you still don't want them all set to different. Valve lash effects the opening and closing timing just as much as the cam profile does. Set them all the same, and each cylinder will act the same. Doesn't matter if the lash is wide or tight as long as they are alike. Will it matter in the long run, probably not, by why not start with the correct settings.

joe

I'm an old geezer and get confused easily. Are you trying to tell us that an old GMC will run just as well with all of the exhaust valves set at .002 as it will if they are set at the recommended .020 just as long as they are all set at .002. If this is what you are trying to say, I agree with Jerry.

I prefer to adjust them with the engine hot and not running. Much easier to do, and safer. I am prone to dropping tools, and if i drop a screw driver or wrench at the fan end of the engine, it might come back up to meet me.

Once you get the hang of the order, it doesn't take but a few minutes to adjust the valves.

I have adjusted them while the engine is running, but after dropping a tool or two a time or two it's just safer for me to turn the engine off.

I've rebuilt or worked on many engines since the 1960's. Solid/hydraulic lifters, adjustable/non-adjustable. I set the lash to specs before I start the engine. I took a set of feeler gauges and v'd them, comes in helpful on worn rocker arms. Start the engine, let it warm up, shut it down and reset the lash. At times a rocker arm or two might still be making noise. I'll adjust those with the engine running, just to where they quit clacking. Shut the engine down, and recheck the lash on the offender. It is usually only .002 or less off. I've never burnt a valve. When your stovebolt engine came from the factory, it was a quiet engine. With proper care/maintenance, it will still be quiet. I use the proper adjusting tool as mentioned previously. Be thankful our stovebolts are adjustable, there are a lot of engines out there that aren't. So, click, clack away if that's your choice. Some folks believe that's music to their ears. To mine, it's telling me that something isn't right.

Rick

Setting the lash with the engine running was the only way we knew back in the 50's and early 60's. I have The valve adjusting tool and a go,no go feeler gauge. We set the valves on the newer engines with hydraulic lifters by backing the nut on the rocker arm off until it you could hear it click then tighten up until the clicking stopped and then maybe a quarter of a turn further. I believe that is the way the manuals said to do it.
Jim

A push rod engine never leaves the shop that has had a feeler gauge anywhere near the valve train. It takes longer but when the valves have been set with a P&G Valve Gapper then the clearance is correct no matter what the condition of the rockers, the rocker shafts, push rod ends, and even takes in the oil film strength. We make our own blocks, heads, crankshafts, camshafts, pistons, and clutch assembly so with mega bucks tied up everything has to be dead on---no excuses. Our machines are only for our own use; no outside work to cause out of tolerance wear. One mistake and the competition wins.

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Some of what Hotrod is telling you in his own way:
http://www.camcoindex.com/svcman/moonbook.pdf
For those who want, some of the stuff a cam does(not a complete list) are as follows: Lift(just one thing), Accelerate(just one more thing), Degree timing( another thing),Decelerate(another thing), and it matters if you have a flat follower(tappet) or a roller follower. The intake valve is cooled by the air-fuel mixture(smaller "lash") The exhaust valve is heated by the outgoing charge(larger "lash") With funky wear on valve stems, rocker arms, and pushrods, not to mention the lifter(tappet), and cam. You can see why there is a "recommended" clearance between the rocker arm and the valve stem. Add hydraulic lifters and let the fun begin. For most of us, set to the book seems like a good idea.

Yes - set valve lash to the recommended settings.

The Chevrolet book is unclear regarding technique - do it running or stopped - just make sure the engine has been warmed up.

Take the silliness to the Greasy Spoon.

The Truck Shop Manual complicates it further by providing larger gaps for "heavy duty operation."
BTW, I think it is plenty silly enough in the greasy spoon.
Carl

What I ment about adjusting them all the same was, each valve the same with-in the spec's of what the engine calls for. If you wish to adjust them on the tighter side of the spec, so be it, as long as the other 5 are the same setting.

Point is, use a feeler gauge, running or not, and up to temperature if possible. If setting them cold, add a .001" or .002" for expansion once warmed up. I tend to set lash on the tight side ( but still in spec ), due to parts wear. Lash always gets bigger, so in the long run the adjustment stays with in spec for a longer amount of time.

One would think the lash would always get bigger with wear, but as the valve seats wears the lash can actually decrease.
I have seen this on engines that had been run with the timing set on the retarded side.

I have never seen valve lash get bigger due to normal wear. Valves wear into the seats and the valves get tighter. Heavy duty operation means driving them like we used to drive trucks. Wide open throttle all the time except when we needed to stop. This is why heavy duty operation also calls for a colder spark plug. Our GMCs with solid lifters had to be regularly adjusted to keep the exhaust valves especially, from getting too tight and burning valves. Adjusting them a little on the tight side just to quiet them down is probably OK if you really baby the engine and don't demand much ofit.

The air cooled Volkswagen engines I ran back in the late 1960's were notorious for burning valves until I learned to run the exhaust valve clearance a couple of thousandths loose. Stovebolts don't have quite as much of a problem because they're liquid cooled, but too tight is always more likely to cause rough running and/or valve burning than adjusting the clearance a bit loose and putting up with a little tick noise.
Jerry