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engine popping thru carburetor


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rebuilt motor but now when you try to rev up on it it wants to pop thru the carb has everything new in it cam lifters push rods timing chain and gears idles fine just cant rev it up any suggestions would be appreciated  I've moved timing every which way to see if it would help but doesn't seem to help any

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Were the cylinder heads redone.??..Were Valves ground and sealing good.??  Are all the valve stems the same height.?? With new matching valve springs locks and retainers and not coil binding??...Hydraulic or solid lifters.??..Also what method did you use to set the valve lash..?? 

Edited by TWO LANE BLACK TOP
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When you bottomed out the rockers....You more than likely have way too much preload on the lifters...Even though they are hydraulic you can't just lock them down..Can cause all kinds of problems..(Erratic idle..Won't rev like they should...Among lots of other issues some of them severe)..

  Best thing to do is pull the valve covers and readjust all the valves...Starting with #1 cylinder back both the rockers off..intake and exhaust..Just enough so they are slightly loose...Using a socket and a breaker bar on the crank bolt rotate the engine by hand clockwise (Remove all the plugs will rotate fairly easy). Watch the exhaust valve when it opens half way.. Stop right there..Using two fingers move the push rod on the intake side up and down while SLOWLY tightening the intake rocker down just as soon as the push rod stops moving up and down and there is no slack...Stop right there... That is zero lash...Should not be pressing down on the lifter at all... Once you get to that point tighten down the rocker nut one half turn ... Then rotate the engine while watching the intake valve when it opens all the way then closes halfway... Stop right there... Do the same thing with the pushrod on the exhaust side up and down when you have zero lash...tighten the rocker nut one half turn...Do the same thing on all the cylinders...Be sure to watch the valves is very important,..exhaust half way down set intake...Intake valve all the way open then close half way..set exhaust...Repeat on all the cylinders...Might have to go thru it a couple times to get exactly right.....

Please..Let me know what happens....also please post here on this thread so everyone can see

Edited by TWO LANE BLACK TOP
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4 hours ago, TWO LANE BLACK TOP said:

When you bottomed out the rockers....You more than likely have way too much preload on the lifters...Even though they are hydraulic you can't just lock them down..Can cause all kinds of problems..(Erratic idle..Won't rev like they should...Among lots of other issues some of them severe)..

  Best thing to do is pull the valve covers and readjust all the valves...Starting with #1 cylinder back both the rockers off..intake and exhaust..Just enough so they are slightly loose...Using a socket and a breaker bar on the crank bolt rotate the engine by hand clockwise (Remove all the plugs will rotate fairly easy). Watch the exhaust valve when it opens half way.. Stop right there..Using two fingers move the push rod on the intake side up and down while SLOWLY tightening the intake rocker down just as soon as the push rod stops moving up and down and there is no slack...Stop right there... That is zero lash...Should not be pressing down on the lifter at all... Once you get to that point tighten down the rocker nut one half turn ... Then rotate the engine while watching the intake valve when it opens all the way then closes halfway... Stop right there... Do the same thing with the pushrod on the exhaust side up and down when you have zero lash...tighten the rocker nut one half turn...Do the same thing on all the cylinders...Be sure to watch the valves is very important,..exhaust half way down set intake...Intake valve all the way open then close half way..set exhaust...Repeat on all the cylinders...Might have to go thru it a couple times to get exactly right.....

Please..Let me know what happens....also please post here on this thread so everyone can see

thanks so much for the info am anxious to try that. I was always told to just tighten them all the way down before hoping this does the trick  will let you know soon as I get it done would be nice to be able to get the old girl back on the road

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  • 4 months later...

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