The Stovebolt Site Forums The Shop Area Engine Shop valve adjustment (baby steps)

Evening. I've never adjusted valves before, so I'm getting my feet wet tonight. I'm working with a COLD ENGINE, just as a dry run. I'm using Hotrod Lincoln's "companion cylinder" approach. Could someone please check my thinking here?

Following HRL's steps, I've got the #6 intake valve just beginning to open, which means the #1 valves are both completely closed and not on a cam lobe (terminology?). I then try to insert a feeler gauge (0.007" for intake, 0.014" for exhaust, per the shop manual), where the rocker arm meets the push rod. However, the feeler gauge doesn't even begin to enter the space, because no space exists.

My thinking is, if one is supposed to check clearance in a hot engine, and things expand when hot, then clearance would be tighter when hot and looser when cold. So if I have zero clearance with a cold engine, things would be excessively tight with a hot engine (i.e., the adjusting screws are much too tight).

Is my logic sound? I hate to back off the screws a bunch because the engine runs, and I don't want to make it not run (I have a history of breaking stuff that worked before I touched it. Like my poor old speedometer. But I digress.).

Any thoughts out there? Thanks!

Ol'Red You got to check where the rocker arm meets the valve stem. "Not where it meets the push rod". The valve stem is at the other end of the rocker arm .

What's the possibility the engine has been swapped for one with hydraulic lifters? Have you done any research on the numbers stamped on the machined pad behind the distributor? If the valves are actually that tight, the engine would be running really lousy (or not at all) if it has solid lifters. Hydraulics run at a "zero lash" situation because the lifters are pre-loaded during their initial adjustment.

Try this- - - -Using a pry bar or a long screwdriver, and apply a firm pressure to one of the #1 cylinder rocker arms like you were trying to force the pushrod down into the engine. If a gap appears between the tip of the rocker and the valve stem after holding the pressure for 2-3 minutes and eventually goes to 1/8" or so, you've got hydraulic lifters. If there's no change at the rocker tip after a couple of minutes of constant pressure, the engine has solid lifters.

Good catch, Shaker! The feeler gauge needs to go between the valve stem (with the spring around it) and the tip of the rocker arm, on the opposite end of the rocker from the pushrod!
Jerry

Well it's a little embarrassing that I was checking clearance on the wrong side of the rocker (on the push rod side, as Shaker points out). On the valve side, I can insert the feeler gauge.

I do need to confirm that I don't have hydraulic lifters, but as the title says, baby steps. Thanks guys.

I should add that the companion cylinder approach is pretty easy, because you don't have to look for any marks on the flywheel; you just watch the springs (I removed spark plugs for ease of rotation). Thanks HRL.

Don't be embarrassed, that's how ya learn.

I can't turn the rocker arm adjusting screws with a screwdriver or even with a bit in a socket on a wratchet (and chipped a tiny piece off the screw head doing it). Are these screws supposed to be that difficult to move? Is there something that locks these screws in place? I'll spritz 'em with a bit of penetrant and try again tomorrow. It makes sense that they shouldn't turn easily, but this seems extreme.

Ah,never mind. I see there's a lock nut on the adjusting screw. I'll try it tomorrow.

Do you have a Shop Manual? If not you should invest in one. It usually has step by step and very descriptive passages on anything you will every need to do on these engines. Good luck and keep on learning!

That method of finding TDC works on any engine with an even number of cylinders by splitting the firing order down the middle. On an odd-numbered engine like a 3 or 5 cylinder, find the "rocking" point and then turn the engine one full turn to find TDC on the compression stroke. It's also useful for setting hydraulic lifters with the engine stopped. Just gently find the "zero lash" point, and then turn the adjuster the specified number of turns to preload the lifter.
Jerry

IF you verify that your lifters are indeed solid, please note that the lash specs in your original post are for a hot engine.

Need to add something to that when doing a cold adjustment. I believe the shop manual says to add .005” to the hot lash spec.

I thought so too, but recently looked for valve adjusting instructions in the Chevy manual and they're not included.
Perhaps this was so simple back in the day that it wasn't necessary to write it out, did everyone know how to put the cam on the base circle for each cylinder and adjust the valves?
Was valve adjusting instinctual then and not now?

Here's the page, it says:
....5. Adjust the valve clearances as follows:" (and what follows is just the clearance, no instruction.)
....6. Install rocker arm cover...
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0607.htm

Yes, the Shop Manual and Owner's/Operators Manual are not very good with instructions for setting valve clearances. There is no statement about adjusting with a running engine or with the engine off. Running the engine for 30 minutes before adjusting is stated.

I was taught to adjust with the engine running - ugh.
I have seen photos of valve covers with the tops cut open to contain the splatter when adjusting a running engine.

The "static" methods on a warmed-up engine are cleaner, faster, easier, and most likely more accurate.

How the heck do you adjust them on a running engine? Checking the valve clearance is one of the first things we're doing come spring time.

Hi Apache. Yes, I do have a shop manual, but it's not very descriptive on this topic. It uses 1/4 page to describe why it's so important that the engine be hot, but the one step that addresses the actual adjustment simply says, "Adjust valve clearances as follows", and it gives the specifications. They probably figured, surely anybody reading this book knows how to do this process!

"How the heck do you adjust them on a running engine? "

You do not grit your teeth - that might loosen fillings.

It can also tear/bend/abuse the feeler gauge/gauges.

With the engine warmed/running, loosen the adjustment-screw's nut;
then, turn the adjustment-screw downwards until the feeler cannot be moved;
then, turn the adjustment-screw upwards until the feeler-gauge/blade can be barely moved;
then, tighten.
Repeat for each of the other 11 valves.

Then listen to the valve chatter and wonder if you should do it again (in hopes to get them quieter)?

Running engine procedure sounds awful to me. I’m barely coordinated enough and patient enough to do it on valves that are sitting still.

Perhaps it’s not so bad for someone who’s done it that way for a long time, but not something I will even consider attempting.

Snap-on used to make a GO/NOGO feeler gauge set that was useful for running adjustments. The first 1/2" of the feeler was the correct thickness, and the rest of the blade was .002" thicker. Of course, the tool was very expensive, and most mechanics didn't bother buying it. Feeler gauge blades were sold individually by the parts truck guys, so when the more common ones got battered too badly to use they got replaced instead of buying a whole new set. Stopped engine adjustment after warm-up was much more accurate.
Jerry

"Perhaps it’s not so bad for someone who’s done it that way for a long time, but not something I will even consider attempting."

JW,

If you have someone demonstrate the technique of adjusting the valves with the engine running you will be pleasantly surprised how simple it is and how little time it takes to "Run the rack". A box end wrench the size of the lock nut, screw driver, feeler gauges and a new valve cover gasket are all that is required.

If you end up with a cork valve cover gasket that has shrunk from drying out, cooking it in a cookie sheet full of water on the stove top for a few minutes will bring it right back to the correct size.

You can do it! have fun.

One thing I learned from the first (only) time I tried to adjust my 216 while running was that I can't do it.
I couldn't keep up with the truck even though Grampa never shifted out of first gear...
Actually what I learned was that it was a great way to find out that my rocker arm tips were badly grooved. They chewed up the feeler gauge right quick.
Carl

Carl,

Been there - done that (chewed up feeler gauges - on all my not-so-old 216/235/261 engines).

Chews up feeler-gauges and gives bad "readings".

The first step in my valve lash adjustment procedure on a "new" (to me) engine"

"1. Make sure that each rocker arm surface that mates with the top of the valve stem is smooth. Grind smooth and polish, if necessary."

Running valve adjustments are for people who don't know any better, or don't care about doing quality work.
Jerry

On later model engines with individual rockers, I do the prelim adj;s with engine off and a feeler gauge. I then start it up, warm it up then work the tappers out by sound, feel and smoothness. Both solid and hydraulic.Crank them down until the engine misses then back off until it smooths and doesn't tap.

On common rail rockers I haven't mastered the running technique so it's engine off and feeler gauge. Both my 216 and 235 don't expand much from cold to hot so cold I add only 0.002" to the factory spec., and readjust when warmed up (if needed, i.e. noisey valves).
Ironically, this Magic Hands video at the 15:05 time mark shows the engines getting their valves adjusted via the "running" method.

My 216 was so noisey I couldn't tell if it had internal problems or not. I then pulled the rockers and ground them smooth, taking care to maintain the tip radius, reinstalled and re adjusted, talk about a world of difference, the engine actually "sang" LOL. There were some grooves worn in the tips that had to have been at the least 0.004" deep....

FIRST-TIME TUNEUP COMPLETE!

I adjusted the valve clearance on a COLD engine by adding 0.005 to the recommended clearances (Volfandt, interesting that you've found 0.002 might be better on a 216/235. Maybe for extra credit I'll look at the tips of the rockers). I'll readjust valve clearance after I can take it for a spin and warm it up.

I have now set the ignition timing, adjusted valve clearance, and installed new spark plugs (and adjusted idle speed and mixture, with the aid of the tachometer built into my new timing light). She sounds really good, although I maybe should refer to the truck as a "he", because the new glass-pack muffler has revealed some cajones in the old boy!

I wish I had made an observation of running smoothness after each tuneup operation, but for various reasons, mostly impatience, I did not. As a purely academic exercise, I'm going to assign the following percentages of "contribution to better running":

New spark plugs - 60% of the improvement. The old ones were highly fouled. And because the windshield wiper vacuum hose had been open to atmosphere for about 5 years, I gather that I had too much fuel to the plugs.
Set ignition timing - 30% of the improvement. Before the operation, the octane selector had been set to 8 degrees retarded, and the BB was about 1 inch to the left of the pointer. I set the octane selector to 0 and set the timing.
Valve clearance adjustment - 10% of the improvement. On this cold engine, most of the exhaust valves were fine without adjustment, though a couple had to be loosened. and about half of the intake valves were too tight. None was too loose (needed to be tightened).

The above is just a hunch. I'd be interested in ya'lls comments.

“Actually what I learned was that it was a great way to find out that my rocker arm tips were badly grooved. They chewed up the feeler gauge right quick.”

Carl,

This discussion reminds me of an amusing incident that occurred when I was putting together the engine for my ’36 pickup in the early 1970s. I was able to find everything NOS for a complete head and valve train except the exhaust valves. Being out of options I decided to inquire at the Chevy dealer.

So I went to the dealer parts department and asked the counter man about the availability of 1935-40 Chevy exhaust valves. Typical of the know-it-alls of this world he let out a big guffaw at me even asking about such an obsolete (in his vast knowledge) part. Then he rounded up some of the other parts guys so they could share in his glee. When they were all done enjoying my foolish inquiry I said “Now that you’ve had your fun would you please look up my part?”

It suddenly got real quiet as Mr. Know It All found the part I was looking for, PN 838717, in his then-current parts book. Apparently GM discovered that there was sufficient demand to put those valves back into production. I placed the order and a few days later the valves showed up in a freshly minted GM box. Another example of the value of ignoring the "experts" and doing a little independent inquiry.

Because all these parts were NOS when I started there was no problem with feeler gauges being marred at the valve stem-rocker arm interface.

My '36 engine idles down to such a low RPM that it's super easy to feel the gap with a feeler gauge and get it just right.

Easiest way is to buy the special tool.

The parts guy should have known what virtually everyone with 3 brain cells to rub together here at Stovebolt knows- - - - -the exhaust valves are identical to the ones in most small block V8's. Only anal-retentive purists care about OEM part numbers.
Jerry