Do pushrods cause lower compression?
Thread Starter
Intermediate
Joined: Feb 2025
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Do pushrods cause lower compression?
I just finished a head gasket replacement and I am testing the compression. I set cyl 1 to tdc and set the pushrods so there isnt any lash. I cranked the I havent put new oil in it yet) and the intake pushrod had a lot of lash. my compression test was around 140. whats going on
Melting Slicks
Joined: Feb 2003
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From: Saskatoon Sask.
I just finished a head gasket replacement and I am testing the compression. I set cyl 1 to tdc and set the pushrods so there isnt any lash. I cranked the I havent put new oil in it yet) and the intake pushrod had a lot of lash. my compression test was around 140. whats going on
Thread Starter
Intermediate
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I stuck a pencil into the cyl and felt the piston come up, this is my first time doing my valve train. how much would a pushrod with lash reduce compression? I know I probably set my valves on the exhaust stroke. Also, would a cold compression test affect results
Burning Brakes
Joined: Apr 2014
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What year engine and is it basically stock? Depending on the stock compression ratio and how you did the test, 140 is not necessarily a bad reading. Did you test all cylinders or just the one with excessive valve lash?
Thread Starter
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I have an lt1, Ive seen online compression tests where they get a lot higher. I tested a few other cylinders but i dont really know what im doing with the lash. I got 110 on one cylinder, turned the rocker bolt once on the intake and exhaust and got +15 psi. I think my best test was 150
Burning Brakes
Joined: Apr 2014
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You need to get the valve adjustment correct before you do anything else. At this point it sounds like you’re not even sure where you are. I think you should back off all the rocker nuts and start over. Watch that video I linked as many times as it takes to understand it fully. If you don’t understand what he’s showing in the video exactly, come back here and ask questions. In the end if you follow those instructions properly, it’ll be correct when you’re done.
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Burning Brakes
Joined: Apr 2014
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You should not even be thinking about what psi you have until after you’re positive the engine is properly and fully assembled. That certainly includes proper valve adjustment including the preload. If you’re reassembling with used valve train parts, I’d go 1/2 turn past zero lash as the final step for each valve
Thread Starter
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I retested on cyl 1 with properly adjust valves and im still only getting around 130 psi. I did a wet test and got the same results. should I pull the heads and get a shop to look at them? I think its due to improper head sealing with the gasket
Thread Starter
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I dont really see a reason why thre head gasket would cause a drop in such a subtle drop in psi. my compression tester is a dirt cheap one from china. I dont think its valves, (i tested for leaks when the heads were off). Should I just slap everything together and give it a go? I feel like there are too many variable components that could be affecting compression that should go away once i put everything back together.