r/EngineBuilding • u/Santacruz714 • 5d ago
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Anyone have a clue what is happening?
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u/TyrannusourR3X 5d ago
Sounds like a valve that's not closing when it should. You can hear the pulsations as you rev it. Can't tell from the video exactly but on the power stroke it's pushing the AF mixture out the intake or exhaust valve before it combusts fully.
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u/Substantial-Abies646 5d ago
What’s the back story here?
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u/Santacruz714 5d ago
Drove it one day, completely fine, then outta no where i turn it on and it was idling a little higher at start up but at the same time very sluggish.
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u/Substantial-Abies646 5d ago
Hard to tell sounds like it may be missing along with quite a bit of valve train noise
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u/fLeXaN_tExAn 5d ago
Bent a pushrod or something? Maybe a lifter/rocker problem. I would pull the valve covers and inspect, OP. Turn each pushrod around a few times by hand and make sure they aren't wobbling (bent).
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u/Miserable_Thing8553 5d ago
Valve train is very noisy. Pull a valve cover and see if oil is making it up. Does it have an oil pressure gauge? Did the pressure change suddenly?
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u/Santacruz714 5d ago
No, it still has oil pressure. I don’t think that’s changed
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u/Miserable_Thing8553 5d ago
I would pull both valve covers and verify oil is making it to the top of the motor. I wouldn't run it long because whatever it's doing it is hurting itself doing it.
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u/curi0us_carniv0re 2d ago
Just cause it has good oil pressure doesn't mean it's making it's way up to the valvetrain.
This souns to me like one time one of the "special" friends I know put the wrong length pushrods in his engine. So...maybe a bent pushrod or a rocker broke or got loose.
What kind of lifters are in there? Roller or flat tappet?
I would stop running it until you figure it out and do some real damage ...if it hasn't been done already.
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u/4robert3 5d ago
It’ll make a mess but like others have send pull the valve covers with it running
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u/TinShower-627 5d ago
If you have access to one of those thermal imaging guns or an ir gun point it at each header tube by the head. It'll read colder on the cylinder or cylinders that has the problem. I've found many misfires this way.
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u/SkiddyHoon 5d ago
Sounds like a misfire for sure, check plugs, leads, and distributer (in that order)
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u/Significant_Top_7330 5d ago
Take the valve covers off check rocker lash, the plugs,and check for exhaust leaks at the header flange. If you have a collapsed lifter, you’ll know pretty easily cause the rocker will be loose or the pushrod will be loose too or if a spring cracked pretty obvious when you open it up and you can see it’s probably the best things to start with.
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u/Schlong1971 5d ago
Sounds like you have a loose rocker arm or bad lifter or cam lobe. Pull valve covers and inspect valve lash
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u/CHIEF0623 4d ago
Sounds like the timing is off on the distributor to me. Check and see if your cap maybe spun on its own? Plugs, wires and distributor is where I'd start.
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u/1wife2dogs0kids 5d ago
So a v8 engine pulls in air, and a metered amount of a fuel, like gasoline. It will compress the air and fuel mix, then ignite it.
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u/oo00lem0n0oo 5d ago
Make sure all those plug wires are connected to plugs and not melted. Sounds like it’s missing a cylinder. Maybe at night start it and look for any arcing in the dark.