The Stovebolt Site Forums The Shop Area General Truck Talk 292 valve train woes... Help!

Hi Bolters!

Haven't posted much because school and kids keep me busy as can be.

However, you guys are the ones to ask when issues arise with my daily driver '66 Suburban. So, here goes: My valve train is making a hell of a racket. Not being familiar with hyrdaulic lifters, I'm stymied.

I zero-lashed the rockers yetserday, and it's no better. With the motor running, I backed off each rocker-nut 'til it clattered, then gave each a full turn in quarter turn increments. My head appears to be a later model (It's orange--my motor is green) and I'm wondering if it's been milled, and if this might change rocker-adjustment? Compression is an even 130 across the board. Again, I'm clueless when it comes to hydraulic lifters...

I've listened to the valve train with a stethoscope, and the noise is certainly coming from the cam/lifter area, somewhere around number #5.

Ideas? Suggestions? Jokes at my expense?

Thanks in advance!

This is probably something you don't want to hear, but I'd suggest pulling the side cover and looking at the position of the lifters where they enter the block above the cam. If the lifters at the noisy cylinder(s) are dropping lower in the block with the valve closed, you might be dealing with a worn cam lobe. You can also get an eyeball guess at whether all the lifter plungers are compressed the same distance below the snap ring that keeps the plunger from escaping in case the lifter tops out for some reason. Normally, the plunger should be compressed about 1/16" below the snap ring with the valve seated.

I prefer to adjust hydraulic lifters with the engine stopped. It's MUCH easier to get an accurate adjustment that way. PM me if you want, and I'll send detailed instructions on a non-running adjustment. I'm tired of the experts on the open forum telling me I don't know what I'm talking about.
Jerry

Jerry,

I agree that there are a few 'pretenders to the throne' so I too will take a copy of your instructions to compare with what I have been doing over the years.

Please don't be discouraged, your advice is sound and will stand the test of time.

Regards,

Cosmo

I'll take you up on that offer Jerry. I too thought a static adjustment might be in order. I have a Chilton's Manual here with detailed directions, but I'd welcome the advice of somebody who's actually done it. Thanks!

OK, Cosmo, here goes- - - -

I learned this method from my father, who ran a very successful auto shop in the 40's, 50's, and early 60's, and then spent the next 25 years teaching auto mechanics. He's 84 now, and still doing state-of-the-art work!

Since all 4-stroke engines with an even number of cylinders have two pistons that come to the top of the stroke at the same time ("companion cylinders") it's possible to watch the action of the valves and tell exactly when a cylinder reaches top dead center. For instance, on your 292, the #1 and #6 cylinders reach the top together, but while #1 is on the compression stroke with both valves closed, ready to fire the spark plug, #6 is between exhaust and intake, one full turn out of phase with #1. Here's the trick:

When a cylinder is between exhaust and intake, the exhaust valve will be closing, and the intake will be opening. That's called "overlap", or "rocking". By watching the valves in the overlap position, we can be sure the companion cylinder is exactly on TDC compression- - - -exactly where it needs to be for an accurate valve adjustment! Here's the drill- - - -turn the engine in the normal direction of rotation (clockwise from the front) until the #6 valves are rocking (exhaust closing, intake opening), then loosen both #1 valve adjustments until there's a little slack. This allows the hydraulic lifter to top out fully, something it can never do if the engine is running. Then carefully tighten the adjustment to barely take out the slack. Then turn the nut another 3/4 turn, and the valve is adjusted! Do the same thing for the opther valve on that cylinder- - -back off, take out the clearance, and adjust.

If you turn the engine exactly one turn, now #1 is on overlap, and you can adjust #6. There are three sets of companion cylinders, 1&6, 2&5, and 3&4. Here's an easy way to identify them. The firing order is 1-5-3-6-2-4, so just cut it in half and put the last half under the first:

1-5-3
6-2-4

The companion cylinders are above each other. If you get a cylinder rocking, the next one in the firing order will rock exactly 1/3 of a turn later. You can adjust all 6 cylinders in 2 turns of the engine, no oil splash, no noise, and completely accurate! Try it!

BTW, this method also works for solid lifters, just set the lash instead of preloading the hydraulic lifter.

Oregoon, you've got an IM with the same information!

Thanks for the kind words!
Jerry

Sounds just like the procedure for my old school british motorcycles, without so many confusing cylinders.

Jerry, don't leave us.

Weeds

Is it better to do this hot, or cold?

It works either way. The hydraulic lifter has enough range to compensate for the slight expansion of the valve stem and pushrod that happens at normal operating temperature.
Jerry

GOOD READ Jerry!
I am writin this procedure down on the inside cover of one of my chiltons manuals so I have it forever.
Thanks!
Tim

Thanks again, Jerry. Hopefully get a chance to mess with it Saturday. Pirating the wife's Mercedes Diesel at the present. I miss my truck...

New problem: Truck won't run without half to 3/4 choke. It backfires real bad (both through the pipe, and the carb) misses, and generally sounds horrid.

Engine is in time, has new points, new vacuum advance, plugs, wires, etc.

Any more wisdom?