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Discussion Starter #1
i recently had a pushrod snap, luckily i found both pieces and not much damage was done to the engine, other than the gear on the distributor. but im testing the hydraulic lifters to make sure they will push down. i put the hydraulic lifter on the ground and put force down onto it with the pushrod. but to no avail.. i can't get any of them to move. am i suppose to be able to move them myself? something tells me it requires the force of an engine to move them.. but i need expert advice here. thanks.
 

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Lifters

Hi, once a lifter is "pumped up", I doubt that you could move it as you tried. I'm no expert, but I believe the oil in the lifter is just a cushion, as opposed to a solid lifter that is just what it says, "solid". If the oil in a hydraulic lifter did compress, that would relate in a valve that would not open as much as designed by the cam and rocker arm. I probably did not explain as a real mechanic might have, but I hope this helped.

I'm curious to know what the minor damage was, how the gear on the dist. broke, and what caused it all.

Thanks,
Dennis
 

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The only time a hydraulic lifter plunger will move with that test is if it is just out of a new box with no oil in it or the lifter is bad!!
The purpose of the oil in the lifter is to form a hydraulic column that can't be pushed down. Your lifters are fine. They passed the test.
 

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Re: Lifters

1-bassman said:
Hi, once a lifter is "pumped up", I doubt that you could move it as you tried. I'm no expert, but I believe the oil in the lifter is just a cushion, as opposed to a solid lifter that is just what it says, "solid". If the oil in a hydraulic lifter did compress, that would relate in a valve that would not open as much as designed by the cam and rocker arm. I probably did not explain as a real mechanic might have, but I hope this helped.

I'm curious to know what the minor damage was, how the gear on the dist. broke, and what caused it all.

Thanks,
Dennis
I would like to know how the distributor gear was damaged by a broke pushrod also.

I would also like to know the conditions the engine was under when the pushrod broke.

Something sounds funny here, I have seen bent pushrods, I have even seen pushrods go through the valve covers...but I have yet to see a snapped one in a street engine.

If it snapped (which I don't disbelieve you), you would have to have some bind somewhere in the valve train. A collapsed lifter would give more cushion to a pushrod, not stress.

Oh, and if you are looking for a collapsed lifter, typically it is wear through the bottom...look for a concave condition on the bottom...and see if you can spot a teeny tiny hole.
 

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Discussion Starter #5
pushrod and damage explained

alright well from what can gather, the innermost spring on the valve spring started falling apart. (cylinder #6) faulty spring i suppose. i never overrevved the engine and those heads had roller rockers, screw in studs and guide plates. according to the shop we ordered them from they should had easily been fine up to 5800rpm.. which they were never taken that high anyway. both springs on the exhaust/intake failed. the intake pushrod bent and snapped. the roller rocker on the exhaust snapped at the fulcrum. all this caused a crack in my valve cover, and a loud ticking noise so i turned it off. i went to inspect it and took the engine nearly all the way down. the distributor was hard as hell to pull out.. i had to have someone turn the motor at the crank while i wedged it out slowly. the snapped off piece of the pushrod had been gouged by one tooth of the dist. the other longer piece had stayed on the pushrod hole. hardly any metal is missing.. the two pieces nearly fit together with some exception. i pulled the cam, it is completely fine including the gear. however i can see a few metal shavings had made their way to the first cam bearing and made a few marks... although you cant see any of the bronze so its "OK" in that aspect. as for the other cam bearings ill need a flash light. if it did equal amount of damage to the other cam bearings im going to request the guy that built my heads pay for me a new engine. it barely reached 2000 miles..
 

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Pushrod damage

It sounds like either the wrong springs, junk springs, or someone else ran the rpms too high and floated the valves. I believe that the piston slamed into the valve which in turn snapped the rocker arm and at the same time bent and broke the rod. Make sense to anyone?

Dennis
 

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It's possible 1-bassman

Sagacious, What are the complete specs on the engine (cam, pistons, heads, springs, etc...)?
 

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Discussion Starter #8
specs.

i use comp cams XE268 .477 intake .480 exhaust, speed pro hypereutectic pistons with 4 valve reliefs, moly rings. unsure of the head casting but their cast iron 2.02/1.60, 72cc, bronze guides, 5 angle valve job, screw in studs and guide plates. the springs are "rated" at .500 lift max. proform 1.5 ratio roller rockers. im unsure of the deck height but i know it was milled as it is bored .040 over 357ci. compression ratio has been calculated to approx 9.5:1 - 9.8:1. estimated 375+hp.
 
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