Z28Drifter348

I read into this a few years ago on another forum. The best way to do this is take whichever cylinder to BDC before you release the rockers and the air will act like a spring when you run it. It will not harm the motor. This method has been around for years.

joecar

Sorry, I rambled and wasn't clear...

the air being compressed with valves closed is ok

( think about what happens on compression stroke )

Ferocity02

iTrader: (60)

Good idea. I will give this a shot next week.

vettenuts

iTrader: (4)

There was a recent thread that had a similar problem. It got worse with aftermarket valve springs. I will see if I can find the thread, but he did the trunnion upgrade and it helped immensely if you are running stock rockers.

Found the thread, hopefully it has some good information: Link

chrisfrost

iTrader: (8)

How go You do compression test ? You disable the fuel/spark to all cylinders and put tester in 1 cyl at a time which won't hurt a thing . Lifters will also be just fine with p-rods removed . Before You try that with 1 rocker cover removed at a time ,,,,,,,,squirt some oil down 1 or both p-rods at a time and start it and listen for quieter operation ,,,,,,,,the oil will make it to the lifter and lubricate the lifter for a few and quiet a lifter that has been a little too starved for oil .

99Bluz28

iTrader: (35)

IMO, if you get everything ahead of time (tools,trq specs and sequences, gaskets, coolant, thread lube, sealant, loctite, and cleaning supplies), and make sure you have a shop-vac with a good wet/dry filter you can remove/install the heads in 1 day.

Ferocity02

iTrader: (60)

Thanks for the link. I am already using the Comp upgrade, they are all fine. I moved rockers around and the noise stays put. The noise is coming from deeper in the engine. It's not too noticeable from above, very noticeable from underneath.


I already did a compression test and all is good. Besides, a compression test won't show anything unless the lifter is stuck at the top, which none of them are. I'm trying to isolate a lifter issue here.


I am terribly slow and take my sweet *** time. Even with very few hangups it took me 3 days to do the head/cam swap

Ferocity02

iTrader: (60)

So I got around to doing this tonight. What I did was remove the both rockers and pushrods from a cylinder. Rotate the engine until that cylinder was at BDC. Left in the spark plug. Unplugged and injector and coil for that cylinder. Did this for cylinder 5 and 7 where the noise is coming from. And when I did cylinder 5 the noise was significantly less. I did cylinder 5 twice just to confirm, same results both times.

The preload on this cylinder is 0.091 on the exhaust with a 7.350 pushrod and 0.084 on the intake with a 7.325 pushrod. Putting a 7.325 pushrod on the exhaust valve did not change the noise. I may try a 7.350 on the intake valve to see if it makes the noise better or worse.

Both lifters are physically fine from what I can tell through the valve cover. They bleed down fine when tightening the rocker and pump back up when removing the rocker. I can't push them down by hand. Both rockers are fine, springs are fine.

With the engine running I also just unplugged the injectors and the noise did not go away, so it's probably not something related to the combustion.

Anyone have anymore thoughts? Sounds like it might be a bad lifter, but I was hoping to be able to physically tell that the lifter was bad.

One last ditch effort may be to put Mobil 1 10W-30 back in since the noise started shortly after putting in Rotella 5W-40.

mike13

iTrader: (27)

check for a bent pushrod, it doesn't take much of a bend. Also check to make sure the pushrods aren't touching the head. I never liked 5w oil. Also make sure the rocker isn't touching the baffles in the valve covers.

Ferocity02

iTrader: (60)

It's not doing any of those things. Pushrods are all perfect