big block chevy valve adjustment trouble,no compression - Hot Rod Forum : Hotrodders Bulletin Board
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Old 09-27-2003, 06:20 PM
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big block chevy valve adjustment trouble,no compression

i just put new headgaskets and vakve job on a 366 big block truck motor.i adjusted the valves with engine off.i made sure they were on the base circle then sping the pushrod until it drags then tighten 1\2 turn.when i set them this way it holds the valves open and i have no compression.if i loosen them up it starts right up but the rockers are clicking .when i shut the motor off the rockers are way too loose.i dont know what else to do.anybody have any ideas.
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Old 09-27-2003, 06:51 PM
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Is there any chance you have solid lifters in that motor?? I'm not familiar with the 366.
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Old 09-27-2003, 06:56 PM
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Here is a site,
How to Set Valves the Easy Way
http://www.chevyhiperformance.com/te...lve/index.html

Its good to put down what type of cam and lifters.
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Old 09-27-2003, 07:03 PM
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its just a stock cam and hydraulic lifters .the 366 is just a truck version of a big block chevy.i adjusted the valves exactly like they said to do it on that link and i have no compression.if i loosen them up to where they tic alot it will run.
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Old 09-27-2003, 07:07 PM
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You really have to crank the lifter pre-load to have no compression at all. If you put your weight on the end of the pushrod, does it compress at all??
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Old 09-27-2003, 07:10 PM
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did you let it run long enough to pump the lifter's up? they should quiet down after running for awhile, I think your going to tight on the adjustment..What exactly do you mean no compression? are you using a compression tester?
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Old 09-27-2003, 07:21 PM
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well i just did the turn the nut until i can barely spin the pushrod then turn 1\2 turn more.this is with a warm engine.it will start with them looser than this .do you think i should let it run longer.i can tell i have no compression and its holding the valves open because the engine spins freely no drag at all from compression.

when i loosen them up enough for it to start and run when i shut it off i can remove the valve cover and wobble the rocker arm back and forth on most of them
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Old 09-27-2003, 07:58 PM
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Ok.... when you set the pre-load, you will spin the pushrod with your finger tips, and at the point where you can just barely feel the slightest drag, this is zero lash. Turn the lock nut 1/4 to 1/2 of a turn after this. Make sure that you're on the base circle of each lobe by watching the paired lifter. For example, when setting the intake of cyl #1, turn the engine until the exhaust lifter is just starting to move, then set the intake, etc... Make sure also that your socket is not binding in the rocker body when you're doing this.

And yes, you will be able to rock the rockers from side to side with the correct lifter pre-load.
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Old 09-27-2003, 08:53 PM
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I've seen it before, exact same senero, new cam, new lifters, but won't run. Last one ended up having solid lifters in it, parts store made a mistake and handed the guy solids instead of hydraulics. If you can look down the pushrod hole in the head and see the top of the lifter and DON"T see a snap ring inside the top of the lifter, you got problems.
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Old 09-27-2003, 09:42 PM
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yeah maybe i am getting them too tight i didnt think the rockers would move at all when the lash was right.i did the spin the pushrod until drag and then add 1\2 turn on nut on the exhaust valves but the intakes are so short and high on the big block i couldnt get my fingers in there too good and the were hot so i was rocking them.this isnt a new cam its the one that was in there but this motor hasnt been ran in about 2 years.i just removed the heads for a valve job.the lifters are hydraulic for sure.is there anyway i can get them close while the engine is cold.thanx so much for your help guys.

heres is the procedure i used to adjust

http://www.centuryperformance.com/valveadjustment.asp

i think the rocker arm wobble was throwing me off i think ill try adjusting the valves in the link you guys posted here in the morning.do you think it will be far off if i do it cold.

Last edited by dufrain; 09-27-2003 at 09:42 PM.
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Old 09-27-2003, 09:45 PM
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You can do it this way cold too. Did you prime the lifters?? You would have submerged them in oil in a suitable container on your bench, and used a push rod to pump them until they are hard. They will pump up when the engine starts, but they make a heck of a racket for a good 10 secs or so.
Not to bum you out.... but I have seen lifters permanently damaged after doing what you've just done. sorry.
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Old 09-28-2003, 08:07 AM
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Adjust them cold to zero, start it and try a 1/4 turn or where it will run.

After setting for that long the lifters could be collapsed. I`ve had this happen before.

Good Luck
Troy
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