Valve lash problem

[liquidrush]

My valve clearance opens up past .020 after the engine warms up. I just finished a cold, overnight sit adjustment to 006, started it up and within 6 or so minutes it sounded like I left the adjusters loose on both sides. I pulled the covers and grabbed a feeler gauge who's thickest gauge is a 25 and the 20 flops lose under intakes and exhausts on both sides and I can feel them. It's a 73 AH 1600 and I've been chasing this problem for a year. It's a buggy so it's not driven daily but this problem is getting old. It's got new cylinder heads and rocker shafts, I've used several different sets of adjusters including factory, elephant feet and the balls with flats, installed new aluminum pushrods and the only way I can get it to sort of quiet down is to hot adjust them which is difficult. It's not an exhaust leak or other noise, it's valve noise. The rocker shafts have about 006 all the way through, I've checked this several times including this morning prior to cold adjustment. Not sure what else I can tell you about it.

[Bugsy61]

What you are describing is exactly the way steel push rods react. Are you sure your push rods are aluminum? The engine is expanding at a rate faster than your push rods. If it does this consistently, I would adjust them to zero lash cold, and check them hot to see what you have. One summer, I even adjusted my steel push rods to negative lash just for an experiment. I set it zero lash, plus a fraction of a turn in. It started normally, and within a couple minutes run time, I had a couple thousandths free lash. It ran real quiet, and did not burn a valve. Not suggesting you do that, but just sayin', don't be afraid to try something different.

[mark tucker]

lifters dieing, cam dieing,something dyeing, not adjusted right, coil bind, pushrod to pushrod interfearance/binding, adjusters dyeing, pushrods eating cup,rocker shafts on rong,...som ting rong....take your pick. check it all dont just change parts.loose heads.... rocker studs loose, rockers shafts loose...figure it out, you are there we are hear, find it and we will try to help.

[Axitech]

Hot adjust? I’ve always done them cold.
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[jeffrey8164]

Post a picture of your pushrods.
Or at least one of them.
Then we can tell if they’re chromoly or aluminum.

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[nsracing]

If the engine is old -that will explain it. maybe the studs/ nuts have loosened and the heads are not seated anymore. If the heads have loosened, they will etch and dig into the heads and pound the case. No amount of adjustment on the rockers will fix this.

If the motor is fairly new, maybe do a re-torque on the head studs. Then check the valve lash again.

What is leaving the motor sit overnite have to do w/ anything? AFter running the engine, just let it cool some so you don't burn your hands and adjust the valve lash. What is this overnite crap?

And you let this run a whole year without figuring it out and fixing it? I just hope you did not chew the lifters and cam lobes.

[mark tucker]

I adjust mine hot~warm...20 min cool down tyme. but your aint mine and I didnt build your so....

[Bugsy61]

Aluminum pushrods are not magnetic, except on the ends where the tips are inserted, so you can check with a magnet just by removing the valve cover.

[liquidrush]

Problem solved. When I set up my rocker shafts I made clearances in three places, left, center which is between the shaft stanchions and right. Luckily, I happened to notice the center intake rockers and the spacer would move left to right while I was pushing and pulling on the arms. I incorrectly assumed that when tightened down I should have about .005 in each area. It seems that wound up being too much so I re shimmed the rocker arms to have .005 total clearance end to end and it cured the clatter. I asked about shaft clearance before but I guess I wasn't specific enough so lesson learned. My push rods are aluminum, I just bought them new not too long ago and I adjusted valve clearance not hot but not cold either. It's so nice to have the engine quiet like I remember all of the others I've had over the years. After this season it's coming out and will get a complete overhaul, nothing fancy, just a plain, solid stock rebuild.

[mark tucker]

lash and side clearance are different...I like my sides to be .002"