Valvetrain noise after rebuild

glanngfor · 10-24-2009, 12:38 PM

I'm having trouble with the valve-train on a 96 3.1 engine. Just rebuilt due to a broken cam. This one has the stamped rocker arms, but does have the 769 heads (rebuilt). The motor has a lifter tick and I can't seem to get it to quiet down. I'm thinking maybe one of the lifters is bad, or was damaged when the cam went. So far I've installed new push rods and re-torqued the rockers with the same issue. It sounds like its getting worse, so I guess I'll be pulling the intakes back off.

So here's my question. There is a 96 lumina over at pull-apart with a 3.1 and it has the roller rocker setup. My thinking is to take the rockers, studs and lifters and install these in mine. After reading through all the post, it looks like its possible.

I realize that I'll be changing the LIM gaskets with the push rod guides.

What I've gathered on other posts, roller rocker valve adjustment is to bring each piston up to TDC, adjust to 0 lash and turn an additional 3/4. Can someone tell me if this is correct.

Compression testing is showing around 155 pounds on all 6 cylinders, so I'm thinking the bottom end is ok.

I'm just trying to get this engine up and going for my daughter, so I'm trying this myself. Any sound advice would really be appreciated.

Thanks...

betterthanyou · 10-24-2009, 01:20 PM

Well I was going to say bent valve but you have compression on all cylinders so thats a good sign. Bringing each piston to TDC is not the correct way to adjust the valves. The correct way is to rotate the engine and watch the rocker arms. When the exhaust begins to open adjust the intake valve and when the intake valve fully opens and then closes slightly adjust the exhaust valve. I would also add 1 full turn after zero lash. When you replaced the cam please tell me you used new lifters.

**bszopi** · 10-24-2009, 01:40 PM

The correct way to set lash on the 3x00s is to just torque the rockers to the specs. No lash required.

CNCguy · 10-24-2009, 01:54 PM

I am curious if cam bearings were replaced. The cam bearings were destroyed in the engines that I have seen with broken cams.

betterthanyou · 10-24-2009, 02:50 PM

Quote:

Originally Posted by bszopi

The correct way to set lash on the 3x00s is to just torque the rockers to the specs. No lash required.

Right I didn't even notice it was a 96 so there should be no adjustment on stock roller fulcrum rockers. Just torque them down.

glanngfor · 10-24-2009, 03:12 PM

Well I replaced the lifters around a year ago while doing a LIM repair. I'm now showing my lack of experience. I did not inspect or replace the lifters (my bad). The cam bearings were replaced at the machine shop. I don't think any of the valves are bent on the heads. Thanks for the advice. I appreciate it.

Superdave · 10-24-2009, 05:52 PM

I'd pull the lower intake and check out the lifters, you could have a chunk of metal stuck in one stopping it from pumping up.

glanngfor · 10-24-2009, 06:29 PM

Ok, that will be my next step. Is there anyway that you can visually tell if a lifter has not pumped up after pulling the intake?

no_doz · 10-24-2009, 06:32 PM

you might have a bent pushrod...

pmaniac69 · 10-24-2009, 08:14 PM

Quote:

Originally Posted by bszopi

The correct way to set lash on the 3x00s is to just torque the rockers to the specs. No lash required.

thast what I was thinking, same thing with the gen2 engines I believe also, I torqued them all down, rotated the motor a few times, and checked them again

I did this process about 3 times just to be safe