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Lifter Pump Up Problems Driving Me Mental!

r31et
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r31et Explorer

r31et

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hey all so ive built an rb30de ( will turbo it later but for rwc no turbo cos its in a aus r31) the build consists of.

-r33 rb25det vct head with non vct cams.

-rb20det red top cams.

-standard rb30 bottom end.

-rb25det oil pump.

-series 2 ecu/coil packs and loom.

my first problem was a rattle in the top end at around 3500-4000rpm, and a missfire that would only occur when the motor was cold and the motor was given a little rev it would drop a cylinder and pick it back up when the motor had a bit of heat in it, so i pulled out the lifters and pulled them apart and cleaned and primed them and got rid of the vct cams because thats where the rattle was coming from, fixed that rattle but its now an absolute nighmare to start from cold, what seems to be happening is that the exhaust side lifters are pumping up on cold start and holding the valves open a touch, it starts up perfect but a few seconds after it starts when it gains full oil pressure its dies and when cranking to start it up again it sounds like only half the cylinders have compression. the only way to get it going is and soon as the motor fired bring the revs up to about 3.5k (the combustion pressures must be enough to keep the valves from opening) till it has warmed the oil a bit and then it runs absolutely perfect, no issues whatsoever.

Im starting to run out of ideas as to what could be wrong with the damn thing so if anyone has any ideas id really appreciate it!

r31et Explorer

r31et

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did you use reground cams/new lifters? if you mix n match secondhand parts they will rattle(noisy) for sure

No they are the original lifters for that head and rb20 red top cams, I have no rattles, they exact opposite the lifters do more than taking up the lash between lifters and cams they over do it an start opening valves when they should be shut

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