Hey I got a 95 camaro z28 with 5.7 lt1 i just purchased a few weeks ago that had issues and was bought for a cheap price. The owner said it needed a tune up and the trans wouldnt shift right. Well a few shift solenoids later we have all the gears and the trans is completely there for me so now onto the tune up. I noticed while tinkering around one day with it that if i cracked the throttle you could hear a pop in the air ram. Led me to a valve issue problem instead of the previous owner assumed fouled out plugs. So I pulled the valve covers and found several rocker arms loose and a few acctually popped off the spring. So off with the intake to do some more investigating acctually found a roller completely popped out of the lifter. So I buy all new lifters soak them in some oil for a few hours install and get everything to spec according to book. I have a guy from work (32 years experience gm tech) and adjust the rockers as i heard they were tricky. well according to him everything moved up and down as it should so i went ahead and installed the intake and hooked everyhthing back up. few hours later its running, purring like a kitten no chattering idles fine. So i go to take it for a drive, low rpms cruising conditions and all of a sudden the loss of power reoccurs, total of 30 minutes run time and it has popped the rockers off again. so i examine some more and so do a few other technicians from work. none of the rocker arm nuts are backing off and it seems the lifters are not staying pumped up. i know for sure its got oil pressure or else it would have blown up a long time ago. also found the oil pump driveshaft in the rear of the block had a crack or two and the car has fresh headgaskets. was wondering if a short overheat could stress that plastic enough to let oil blow by and not keep lifters pumped up. i am stumped. any help is appreciated thanks.

 

If you had lifters that had the rollers gone out of them and yet the tech with 32 years experience didn't tell you to install a new cam?? He must not be much of a mechanic.

 

Are they self aligning rockers or non self aligning rockers ? Possibly with no guide plates ?

 

I agree.....FWIW, to the OP, once that roller comes out of the lifter, the EDGES of it start riding on the cam. Think about that!!

 

that cam must be poo-pooed lol! the moment that roller fell out that cam was toast.

 

Good questions.

I would also add the question is the cam stock? Maybe some retard put in an aftermartket cam with stock springs and it is just smashing things up?

 

he said everything moved up and down as it should. It just popped the push rod out and the cam probably pushed the lifter out. Could be wrong he probably hasn't worked on one since the 90s so I'm on here looking for guys who wrench on them often.

 

no guide plates. Also an update I replaced the cracked oil pump drive shaft but according to the book the plastic part is just a dumby shaft and serves no purpose in oiling the lifters.

 

Completely stock lt1. One owner. Friend of mine. He did the head gaskets and then this issue arrived a month later.

 

OP -

If (and this is a BIG if) your cam, lifters, push rods, and self-aligning roller rocker arms are all OK, then it may just have been a case of too little pre-load on the hydraulic roller lifters.

The internet "wisdom" says anywhere from 1/2 to 3/4 of a turn after the zero point. For stock GM lifters this is too little. My step-father (also a GM Master Mechanic) told me one full rotation. Previously, I had my lifters adjusted at 3/4ths of a turn (and they ticked slightly); however, after setting them to 1 full turn past the zero point, the 'tick' vanished.

I hope all your parts are OK.

If they are, then try re-adjusting your pre-load.

Good luck!

 

These are all client related.

 

So if my camshaft is smoked. Worst case scenario I can afford to rebuild the whole top end. Anyone know a good aftermarket setup including intake that has good low and mid power? That still maintains driveability. I'm new to this website sorry if I'm not posting this right.

 

Also..what keeps the lifters pumped up in these engines? Cam bearings? Or is there galleys in the block.

 

You are off to a bad start with your blind assumption there is an intake upgrade. The only off the shelf intake option we have is the Edelbrock and the BEST case magazine build advertizements have a hard time pretending it is anything but an expensive mistake.

If the cam bearings spun I would just get a used engine.

 

Keep in mind, if the camshaft and the one bad lifter got chewed up, all that metal has been circulated throughout the engine. The "lower end" might be in worse shape than you think......

 

While what you say is true, HE ONLY HAS 6 POST!!! DAMN, cut a guy some slack! How does he know (in 6 post and admittedly no knowledge of these engines) that there is no upgrade for our type of intakes?? It is very nice of you to try to help him make the right choice in his "build" , but you need to go to manners school so they can teach you how to "reach your audience". When you INSTANTLY bash someone and try to make them feel inferior to yourself you make them go on the defensive and shut down. Please, go learn to talk to people, come back with your VAST knowledge (and I really feel it's fairly vast) and share it with the LT1 world. You have a lot of information to share and help people ,BUT you lose all of the respect from the LT1 community because of your HORRIBLE approach to everyone's "mistakes".


And, before you say it....I'm sure you don't care about respect (actually it's obvious that you don't).


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