[newuser]

Hey guys, I recently adjusted my valves and found them to be waaay out of spec. Was wondering if this has any specific symptoms other than a noisy top end? Would this result in too little air flow into the cylinders/fouled plugs?

Thanks,

Jon

 

[fxray]

Valve clearance affects valve timing (but not ignition timing). In simple terms, the more clearance they have, the later they will open, and the sooner they will close relative to the movement of the piston. If they are far enough off, it will affect your engine performance.

Ray

 

[newuser]

Thanks fxray. Any certain symptoms in particular? Low power, bogging rpms, fouled plugs, etc.

 

[frogman79]

Well, if you can't breath well, you huff and puff when you try to drag around something heavy right?

Engines are the same way, they need to get as much air and fuel mixture in as they can so they can compress and burn it and then they need to get the exhaust gases out as fast as possible so they can start the process over again. Just think of them as an air pump, they are most efficient when they can breath correctly.

I think you would find you would have to be grossly loose though to cause the problems you describe however you might notice decreased compression since the the engine can't suck as much air in as it should to compress it.

How far over were the valves? How is the compression now? Does the engine burn oil? Many things can cause fouled plugs and loss of power, I have a little write up I keep saved that helps explain it. Check out some of the the other articles as well.

Reading Spark Plugs

 

[fxray]

newuser,

I agree with what Fran said. To be honest, I have never tried to run an engine with really loose valves so I have not experienced what the symptoms would be. I will say that valves which are misadjusted loose are not as serious a problem as valves that are too tight. A tight valve setting means that the valve cannot seat properly. Exhaust valves need to transfer heat while they are closed or they keep getting hotter and hotter. Combustion escaping past a valve that is off its seat can burn away part of the valve and the situation gets worse rapidly. As you said, loose valves will be noisier than those which are set correctly, and this could maybe lead to faster wear. It's best to set them to what the manufacturer spec'd, but there is an old saying, "A rappy tappet is a happy tappet".

 

[Yendor]

Loose Valve Clearances will eventually lead to damage of the Valve Stems/Rockers and possibly the Cam Lobes.

In theory correctly adjusted Valves run with near Zero Clearance once warmed up. The Rockers are riding on only a film of oil as the Cam Rotates and the Valve Stem is all but in constant contact with the opposite end of the Rocker.

Once that space opens up the Rockers will start to HAMMER on the ends of the Valve Stems and in the long run damage the Valve Stem ends and the rocker and the Cam lobes.

 

[newuser]

frogman and fxray,

I might have accidentally used inches instead of mm, cough cough, little mistake on my part. So that might qualify for grossly loose. And great write-up frogman.

Yendor,

That definitely makes sense, I've been hearing the loud tapping for a while now but hopefully not long enough to cause all the damage you mentioned.