valve job gone wrong


Junior Member
Corpus Christi
i just adjusted valve lash and changed the plugs on my chevy350. its a brand new engine and the compression was a little shakey so i did a valve lash adjustment... i swear i followed the book to a "t" and when i put everything back there is no compression anywhere. i can feel air while cranking the engine just out side the spark plug holes but no compression! i did it again hoping i could correct the first mistake but same results again! has anyone heard of this? any suggestions on what i did wrong?
thanks, sawbones.


Senior Member

How reliable is your compression testing methods? You might want to try a different guage. I think, unless you really messed up while adjusting the valves, that the total loss of compression couldn't be achievced through just adjusting the valves. Maybe the engine is a dud.


you have them to tight back them off and try it again you probaly need to make sure you had the order of adjustment right this is why you have no compression the valves are staying open

mike reeh

Senior Member
brand new as in its never been fired before? you were doing the initial valve adjustment?

actually, either way, if you had compression before, OR it was running before, you just adjusted the valves too tight..

were the lifters pumped up? make sure the valve you're adjusting is at the BOTTOM of its lobe on the cam and then adjust the rocker so that there is just a tiny bit of up and down play, then zero that out.. from there adjust it one half of a turn and you're set. goto the next one, and so on.. its quite easy, but it can be misleading if the lifters are not primed.. the plunger will go down too easy sometimes and its hard to find "zero lash" .. dont sweat it, the motor is fine


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