Hal Fisher

I just changed the lifters (ls7) in my 73k mile engine because of a mild tick. Now, after driving it maybe 50 miles it starts ticking real bad if I go over 4.5k rpm. It's oil pressure is only around 20 at idle and I just changed the oil 50 miles ago. The oil pressure goes up to 50 above idle (by 2k it's 50). Once, it kept ticking real bad even at idle until I went a mile (had no choice). So there are the symptoms. It picks up a tick at high rpm that usually goes away once the revs drop. The tick seems like the same area the first tick was (around 3rd or 5th cylinder). Any ideas?

Hal

bw_hunter

Try readjusting your rockers. Sometimes new lifters can be tough to find zero lash on....

Hal Fisher

It wasn't just a slight tick, like something was just a little off. It was a nasty one which then went away very quickly but would flair up at high rpm. How do lifters get their oil?

There are two different methods to find zero lash. There is a finger method when you turn the adjustment screw with your fingers until the pushrods stops spinning. With that adjustment you'll still be able to grab the rocker and wiggle it a little. But, if you use a rachet, it will go a little more (maybe 1/8 of a turn) and even the rocker will be solid (for a moment anyway). So which do most people use, the finger tight method or the rachet tight? We noticed the rockers were a lot noisier if just set to finger zero so we used a ratchet to get it rocker tight. I was going 1/2 pre-load once again using the LS7 lifters (could not find what they need but like I said, the rockers were noisey if we went less pre-load).

I have Crane Gold self-aligning rockers and Manley springs. Don't remember the lift on the springs but they are not the strongest ones (single spring and dampner, bought in 1999).

Hal

Maverick_997

check for a exhaust leak, i had one and it sounded very similar to loose rockers

bw_hunter

I personally don't like the twist the rod until the drag goes away method. I move the tube up and down while tightening the rockers until all movment is arrested then add 1/2 to 3/4 of a turn. LS7 lifters are the stock replacements now for all LTx and LSx engines and you should use the same preload that you'd have used before. I run theCrane golds on caddy lifters and 1/2 turn appears to be the middle of the travel...the stock style lifters have a longer travel.

Hal Fisher

I used the ratchet tight method last which sounds like the method you describe so it's certainly not a loose rocker (and like I said it goes completely away until high rpm which at that point it starts ticking very loudly).

I know for sure that 1/2 turn is no where near half the movement of these lifters. They can take about 3 or more full turns before they bottom out.

What oils the lifters? Is there some way just one would not get oil at high rpm?
There was no scaring on the old roller of the lifter when I took it off.

I guess it could just be a bad lifter. I'll have to take the cover off and rev it to hopefully catch it in the act.

Hal

bw_hunter

The lifter gets it's oil from a small feed hole in the blocks lifter bore. It's located at the area wear the lifter necks in.

Hal Fisher

Great. Anyone want to put money against my bet that it's clogged? Maybe at least I can make something off this.

Those lifters only have holes on one side. Is there a certain way the lifters are supposed to go in like hole facing toward the center?

Hal

Hal Fisher

I just thought of a trick way to blow out the lifter/oil port. I'll just stick an air hose on the top of the pushrod while holding the pushrod tight down on the lifter. That might put enough air pressure through the lifter and blow out the obstruction. Is there any real problem with this?

Hal

JAKEJR

Recently someone posted some side by side photos of the LT1 and LS7 lifters to compare the differences.

Thanks for the correction, Hal. I'm editing this post to delete some incorrect information I previously posted and to add this:

From the photos, the lifter plunger of the LS7 lifters is lower than the plunger heights in the LT1 lifters. That indicates to me that the length of the stock pushrod should be checked to make sure the geometry hasn't changed. A longer pushrod may be neded to account for the difference in plunger heights.

Now whether this translates into the possible cause of your tapping, I don't know.

Jake

West Point ROCKS!

JAKEJR

I've never read anything that indicates the oil hole has to face in a certain direction.

There are two basic types of oiling, piddle valve and edge orifice. PD is for NON roller rockers which require more oil up to the rocker arms and the EO reduce oil to the rockers by 10-20% but should ONLY be used with full roller rocker arms which don't require as much oil up top.

One of the most obvious ways to tell which is which is by looking at the placement of the oil hole in the lifter. The EO oil hole will be much higher up, toward the pushrod end of the lifter, NOT in the center.

Some guys use to install BB lifters in a SB and vice-versa, but, as memory serves, the oil holes are placed differently.

If I were you, I'd try more preload, up to one full turn past ZERO lash. This may require a longer pushrod though, so be sure to check to see how the roller tip rides on the valve stem tip.

Jake

West Point ROCKS!

Hal Fisher

"Recently someone posted some side by side photos of the LT1 and LS7 lifters to compare the differences. The photos show the oil holes in the lifters and the plunger seat heights are different."

That was me and it's not true! The LS7 lifter hole is in almost the same exact spot as the stock lifters were ('97). It's ticking on the same lifter it was before I swapped the stockers for new ones. I tried an increased pre-load on the original lifter which did not help.

Because I know the lifter certainly has a lot of internal travel I'll try the additional pre-load again but I'm really hoping the air clears it up. If not the block is scrap as far as I'm concerned. Nobody would want to go through all the effort and expense of cleaning the block and reinstalling it, hoping to have gotten the possible obstruction out.

I will probably let one repetable shop have a look at it before I give up and swap it out. They may know a few tricks that can clear this type of problem.

Hal

Hal Fisher

Just tried this on a mock up with a pushrod and old lifter and it works! Lifter does not have to be pushed down for it to blow through.

Blowing out the passages this way is probably a good thing to do when changing the lifters out or when you have a tick that doesn't respond to rocker adjustment.

Hal

JAKEJR

You're absolutely right; my mistake. I thought the oil holes had been relocated too.

Thanks for correcting my error. I'll go back and edit my post so no one else sees the incorrect information.

Jake

West Point ROCKS

Hal Fisher

The tick turned out to be the #5 intake rocker somehow loosened and popped off the valve head. Only the side of the rocker was pushing the valve down. I know I tightened the lock allen screw. If it does it again (and doesn't destroy the engine in the process) I'm switching to hardened pushrods and guides, and some new rockers. Oh, and I also shot some air down the pushrod. On startup everything was fine and I pushed the revs over 5k and check the rocker one last time before I buttoned it up. Crossing my fingers...

Hal