Pauldana,
Sorry to hijack the thread, but it's the same subject matter so I hope I'll be forgiven. I think I have the same issue with my lifters. They are CC retro rollers. I'm thinking about yanking the intake and bench testing them the same way 682XLR8 did. I've already replaced them once 6 months ago, but am willing to accept that I may have gotten a bad brand new batch. My question is how long should the lifter hold a pump? The procedure I plan to use is fire up the motor and let it run for a minute or two and then tear it down, pull the lifters and test. Will that be sufficient to bench test the lifters? My 383 also pulls hard, but I have blow by in amounts that seem excessive. If I cover the PCV valve hole on the passenger side, the oil cap pops off in just a few seconds. The motor is relatively new with only ~5000 miles on it. The motor behaves strangely. Sometimes it's as smooth as glass while going through the gears and other times I can sense a vibration. It's intermittent so I know something is changing within the motor. Thanks and sorry for the hijack.

 

Take a vacume test and a pressure test. You're getting pressure into the valve train area that is also in the crank case. If the vacume gage pulses, put a timing light on each plug, one at a time and see if the light is timed with the pulse of the vacume gage. That will give you a direction to begin your looking.

 

No problem I would like to know what you find, I might learn something from it

 

Indiancreek... has a interesting idea... never tried it before but sounds feasible... try it...


ok, lifters here.... if they are making ANY noise, sewing machine, ticking, zinging, any noise, you probably have a problem... when they are all running and adjusted right, you will hear nothing, nothing to speak of that is. .... if you do a search on my threads, loosing HP, lifters, springs.... i went through it all...

Take the valve covers off, start the engine and let the oil pressure come up and idle about 1K for about 30 sec, ... turn off engine, take something like a wood hammer handle and go around and push like hell on the push side of the lifter, if you get ANY push down, you got a problem... now this only will work on valves that are closed... so you need to crank the engine again to check those that were compressed... or just do what i did is just back off all the RR nuts until loose right after engine just ran then check all H-lifters for pump, if any are not rock hard, replace. i had 3 bad, checked that way, and CC agreed.

before replacing, i had a little tick every once in a while... change oil it would kind of go away, LOTS of blow by (still have a little but around 90% less) power pulled to 6000, but kind of starting to flattened out about 3500-4000.... now pulls harder the higher she revs, feels like at 6000 rpm she is pulling harder than at 4000rpm... huge difference, ... when i really noticed this is when a new C6 pulled on me after 80-90mph which never happened before, replaced the lifters.... :-)... this no longer happens, now im back with the C6 Z's to ~130... then i run out of RPM...

Also, i would suggest to do a leak down test, you can get the kit at harbor freight cheap...

hope that helps. p:-)

 

OK guys, I'm on lunch break.
IndianCreek: Thanks for the suggestion. That is a really cool idea.

Pauldana: I do have noise. It's at the top of the motor and it only occurs when the engine is cold. It's a knock and I attributed it to forged piston slap or a wrist pin because it goes away after the car warms up. But I do have the intermittent ticking that you are referring to. I will do the test that you recommend. I'm hoping to find some bad lifters! Off comes the intake again! Thanks and will keep you posted.

 

A bad lifter can start as a knock, once it starts to try and pump it turns into a tick.... I would be very suspicious at this point about the lifters, or not being adjusted properly.

 

Pauldana:
I will test and re-adjust before I take it all apart.
Thank you again.

 

The lifters I had mentioned earlier weren't making any noise, just not staying pumped. Does that sound right?

 

if they were not making any noise, and they were not pumping, then they were not adjusted correctly, and way to tight to get past the tick... this could very well hold a valve partially open to give bad compression... sound familiar?

 

Compression was good on both those cylinders

 

Well everyone, I tested the lifters tonight. They all felt like solid lifters.
My procedure:
-Fired her up and let her idle for 3 or 4 minutes

-Pulled the valve covers

-Loosened the rockers all the way out until I had slack between the rocker and the push rod. All rockers are level at this time.

-Took a framing hammer with a rubber handle and pushed like crazy on rockers at the tip where the rocker meets the push rod

Nada. No movement. It was like I was trying to poke a hole through the intake with the end of my hammer. Solid.

Don't know what I feel now. Kind of anticlimactic. I wanted a bad lifter. Something I could zero in on. Now I think I just didn't adjust the valves correctly. When I replaced the lifters 6 months or so ago, I could push the lifter up and down with my hand with ease. The Vette is up on ramps so my leverage wasn't great, but I still feel I had enough leverage to lean on them pretty good. At least I don't have to pull the intake.
I will adjust them again tomorrow night and see where we are at. Will post results. Thanks again to all who have helped me.

 

yea... when they are nt adjusted correctly they will drive you

1. when you first put the lifters in you have 0 pump, this is the best time to use a dial gauge to set lash. the reason is, 0 lash is set when the push rod first meets the lifter and it becomes taunt, not tight, then (i forgot the exact measurement) set. in my case it turned out to be almost exactly .75 turn past 0 lash. But now that you have pump you can not do it that way. with pump, set to 0 lash and turn .75 and I would bet you will be very very close.

Also, bad valve guides can also produce blow-by

 

Compression can run ok with bad lifters, its the spring and closed valve that give you your compression, the lifter only has to open the valve very little to bring in air, and if a lifter is bad it will usually still open a little,,, just not a lot... therefor good compression.... bad running... and noisy lifters..

 

A-HA!

You may have seen on my other thread the shop found 7 bad guides, all of them exhaust

 

Well,
Got everything back together. Still had that knock. Car ran much smoother and blow by was diminished greatly so I know I'm on the right track. Drove it around today and discovered that now it has a knock all the time. It's not a rod knock. This is in the upper part of the motor and it sounds like a tappet. When I adjusted the valves I arrived at zero lash and then added a 1/2 turn. Comp Cams recommends 1/2 to 3/4 turn for their High Energy retro roller hydraulic lifters.

I cut a slot in a valve cover and did a "running" adjustment on the drivers side where the noise was coming from. This didn't do the trick either. I did manage to make a hell of a mess though. Had oil shooting out past the slot of the valve cover. It seems oil pressure is not the issue here. I'm going to back away, take a breath, and try again this week and fully adjust the valves cold again using 3/4 turn this time. If this doesn't do it, I'm thinking I've got a valve issue or something worse. I will run a compression test and a leak down test to see if some of the valves aren't seating. This has really got me mystified. Will keep you posted for the ones who care to know.
Thanks.