I've been working on my 92 Camaro RS with a 305 TBI. My problem is that when I adjust the valves I Tighten them down to zero lash (at least what I think is zero lash on hydraulic lifters) +1/2 turn. On all the valves after the adjust ment seemed loose. The valves where nosy and I could still spin the pushrods and wiggle the rocker arms. I then tightned the valves down some more where the rocker arms wouldn't wilggle and were quite. When i reved the car a little it would stutter and would shake up 1800 RPM's whith a deep exuast soud (Straight pipe to stock dual muffler) but deeper than before when the valves where making noise yet performance was much better? My real question is what exactly is ZERO LASH on hydraulic lifters? also I'm getting 12 mpg and heavy gas smell in the exaust with an occasional backfire at 45 to 55 MPH and it cuts off sometimes after the backfire or when I slow down. What Causes those things? Any help is greatly appreciated.

 

Zero lash on a hydraulic lifter is when all slack in the valve train is taken up, without depressing the plunger on the lifter at all.

 

So the rocker arms shouldn't wiggle at zero lash?

 

The rockers will always wiggle -- when the engine is not running, the lifters bleed down pretty fast and the valve train will be slack. You are probably way past zero lash --

 

so What exactly is no slack in the valvetrain? and should there be a light tap in the motor?

 

Don't worry about "slack", "wiggle", etc.; all terms that are WIDE OPEN to interpretation.

Do it the easy way.

Run the car enough to get the motor hot. Remove the valve covers. Start the engine. As quick as you can, loosen each rocker one at a time until it just begins to clatter, and tighten it back down until it just barely shuts up. Do all 16 this way as fast as you can. Turn the motor off, tighten each one ½ turn more. Put the valve covers back on.

Too simple.

 

Well I basically got it to that pooint adjusting the valves with the engine at around 180 on the temp guage. I sdlusted them with just a slight drag on the valve and pushrod then about 1/2 turn. Then I started the motor and had a litlle valve noise. I stopped the motor and tightened each one about another 1/8 turn to get them to stop moving but still no "Preload" on the valves. it started and ran wonderfully but both valves on cyliner 2, the exuaust valve on cylinder 4, and the exaust valve on cylder 8 all took an additional 1/2 turn to silence but then the car ran like crap. What's going on here?

 

If you adjusted the valves correctly with the motor off, there would be no valve noise on startup. I adjust my valves with the engine off, very carefully using my fingers to determine zero lash as the pushrod barely starts to drag turning it, and I have never had to re adjust once I started the engine. If you can't get the valves adjusted with the engine off that is a red flag -- don't just keep cranking on them with it running or you are going to hang a valve open.

The engine running method is the easiest to get right, but also makes a huge mess. Even with the oil restrictors you can buy, which I do use, it is going to get oil on your exhaust, etc. But it works.

 

Just do it like I said and see what you get. Forget about "drag" and "light" and all that. Too subjective, too open to interpretation, too easy to make a mistake.

Yeah some oil will get out. Good excuse to take a trip to the quarter car wash, and stop and pick up a can of engine degreaser on the way. If you're doing it someplace that will get mad if you get oil on the driveway, put some newspaper or something under it. Just make sure that it doesn't get up into the exhaust and catch fire.

 

I just finished doing the valves that way and before i tightened down the last 1/2 turn on all of them the motor ran great with a slight stutter. after the last 1/2 turn on the valves the car cranked well but stuttered and hesitated really bad.

 

What do you mean the "last half turn", there should be no "last half turn". You get to zero lash and then tighten around 1/2 more. You are NOT tightening the valve adjusters all the way down, that is not how they adjust. If you haven't gotten these right by now, I would see if you can find a friend who is familiar with adjusting valves. You can damage your engine if you keep running it with the lifters bottoming out.

 

Allow me to rephrase: At zero lash the car ran awsome but after the half turn to tighten them down as described the car ran like sh**. I did it exactly like sofakingdom said to do it. I just wanted to let you know how the engine did at each step. I pulled the number one spark plug and it was caked with carbon deposits so I'm going to investigate my spark and timing again. What are the ranges I should get when I OHM my ignition coil to test it? I followed what Chilton said to do to test it but there were no numbers, just high, infinite, or zero. Thanks again for all the help.