Lifters Spent? Bleed Down Too Quick???
Lifters Spent? Bleed Down Too Quick??? I trying to figure out why my freshly built engine doesn't run on all cylinders. This is a 383, with .020 milled LS6 heads, .008 decked block, 224/230, .610"/.605", 114 LSA Comp Cam. It has new MSD wires, NGK TR55 plugs, and has seemingly gotten worse since first firing. G-Force put a 383 tune in, but didn't help the situation.
Here's the latest: I pulled the valve covers and noticed that all the valves are in the closed position. Only a few look like that have any sort of pressure from the cam/lifters/rocker arm. When cranking over, they seem to pump up, but immediately collapse - like within 2-4 seconds to the closed valve. Should the lifters bleed down that quickly? Could this be my problem? Does it sound feasible that the valves just aren't opening enough and this is causing the misfire? I'm about ready to pull the heads and replace the lifters. Please advise!! Thanks!!
Brian
Here's the latest: I pulled the valve covers and noticed that all the valves are in the closed position. Only a few look like that have any sort of pressure from the cam/lifters/rocker arm. When cranking over, they seem to pump up, but immediately collapse - like within 2-4 seconds to the closed valve. Should the lifters bleed down that quickly? Could this be my problem? Does it sound feasible that the valves just aren't opening enough and this is causing the misfire? I'm about ready to pull the heads and replace the lifters. Please advise!! Thanks!!
Brian
I just had my moter torn down to the bare block and when reassembling i roll the crank around so the push rods are all the way down when i torque the rockers down the i roll the crank some more and keep going down the line. My lifters sat on a bench for 2 weeks before I put every thing back together and the towels they were sitting on had oil all over them i didnt soak them before i droped them in and every valve opened and closed and held the valve untill i would turn the crank. I also have dual springs. I would guess that is your problem. I've never seen my oem or comp lifters bleed off as fast as your taking about.
Reading more online today, I'm wondering if it could be a bad crank position sensor. Would this cause the misfires? Would having a different block, different crank throw things off enough for it not to fire properly? I also read about a crank relearn, but G-Force said it wasn't needed unless I had a code for that. Could I still have a bad crank position sensor and not be throwing a code? Hate to have to pull the heads if I don't need to (to replace lifters).
The PCM needs the CKP to know where each cylinder is during the 4 stroke cycle, but that has nothing to do with lifters bleeding down in 2 to 4 seconds. When you button up the top end you should be able to turn the crank manually and see all of the rocker arms rocking as the crank is turning. This is before the engine has been started and the lifters have been "pumped up" with oil. Do you mean this is happening on ALL 16 valves. For this to happen the valve springs would have to over power the lifter springs forcing all the oil out. Highly unusual. If the PCM can't find #1 or any of the other cylinder due to a bad CKP the engine wont' fire(it will crank looking for #1), but that's a different problem from what you describe.
