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Old 04-21-2006, 12:08 PM   #1 (permalink)
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Weird / Strange / HUGE PROBLEM!!! (4.2/4.0L)

not sure if this would qualify as newbie tech, but i'll put it here anyways...

ok i'm stumped...
just got the head back onto my engine, put the push rods and rockers in.. everything is torqued to spec.. now heres the problem...
it seems that ALL the rockers are pushing down the valves a little bit.. (enough that the valves are open a bit) they are all loaded, i can barely move the rockers with my fingers (shouldnt you be able to wiggle them when the valve is closed?)
heres my engine set up... 4.2L block... 4.0L head with 4.2L rockers and push rods.. the block has been rebuilt in 2000 with only about 20,000km and the head was rebuilt in 2003ish with probably 10,000km on it..
now before you say my push rods are too long.. this set up has been working perfectly for about 2 years up until last week when i pulled the head off...
i've taken heads off of this engine before and it has never done anything like this!!! the only thing i can think of is the lifters, but what would be wrong with them to cause this sort of problem? oh and yes, the pushrods are seated properly in the lifters...
any ideas? HELP!!! i want to get this running!!! i wish i didnt take the dam head off in the first place..
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Old 04-21-2006, 02:45 PM   #2 (permalink)
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Well the obvious first step is to reset valve lash. Did you have the block decked or the head shaved? Are you using a different thickness head gasket? how about camshaft? All these things are going to effect your valvetrain geometry. Search my posts of instructions on setting valve lash on your engine. If there's not enough adjustment in the valvetrain to allow the valved to be lashed properly, then yes, you need shorter pushrods.

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Old 04-21-2006, 03:43 PM   #3 (permalink)
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its a 4.2L.. they dont have adjustable valve lash...
block and head were not decked
head gasket is the same thickness
engine ran perfect last week, took kead off to change head gasket and now this..
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Old 04-21-2006, 05:33 PM   #4 (permalink)
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Mine did the same thing. Your hydraulic lifters should compensate - at least mine did. (4.0HO head, 4.2 Block).
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Old 04-21-2006, 07:39 PM   #5 (permalink)
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how long did it take for them to compinsate???
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Old 04-21-2006, 08:28 PM   #6 (permalink)
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As long as it took to fire, 10-15 seconds after engaging the starter? (Also, the mech fuel pump had to fill my float bowl...).

I guaranty that it would not have fired, as far as both the exhaust and intake valves were compressed on assembly, if they remained that way. Made me nervous too.

The only thing I did was mill the head, and place a new head gasket. All other components were previously ran on this engine (head, push rods, etc).
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