2.8L Valve adjustment procedure.

I'm going to be giving my 85' 2.8L XJ a much needed valve job, and I need to know the adjustment procedure. Can anyone help me with this?

The reason I'm doing this is because my engine is tapping, and now that I have the exhaust fixed, it's really noticable how bad the tap actually is. The valve cover gasket needed to be changed anyways, so we're going to crack the engine open and find out why the lifters taping. I basically want to do my research ahead of time so I know what to do once I'm staring at my open engine.

Wow!

That's one of most frustrating bits of research I've done recently. Just looked through the '85 FSM for you. Everywhere there's a possibility of dealing with the valves -- head removal & replace, camshaft removal & replace, etc. -- they say to refer to the Adjustment section for adjusting the valves.

There IS NO adjustment section.

Gotta remember that this is a Chevy engine, and most Chevy engines with hydraulic lifters had adjustable rockers. AMC owned Jeep in 1985, and AMC engines did not have adjustable valves. My guess is that much of the text was copied from a GM manual, and the dolts who put the FSM together never bothered to think about adjustable valves.

All I remember is that it's done with the engine running and that you're shooting for zero lash (zero clearance between the rocker arm and the pushrod). Maybe a Haynes or Chiltons will have more info, or maybe a Chevy mechanic will know without looking it up.

btt...I've got to do this to my wifes xj soon too...

Good thing I brought it up then

I am not sure of the exact spec, but I think that Eagle is correct at 0 lash. I haven't done this adjustment for a few years. I do remember a special tool that is needed. These clips attach to the rockers and keep the oil from flinging everywhere while you make the adjustments.
Click here for the tool needed
Attach these to the rocker arms and start the engine with both valve covers off. Then just tighten the rocker nuts down untill they don't make any more noise. If you tighten them down too much, you will know it by how the smooth the engine is running. This is a very simplified version of the process, but it will work if you can't find the specifics.

Bryan

Bryan C. said:

Then just tighten the rocker nuts down untill they don't make any more noise. If you tighten them down too much, you will know it by how the smooth the engine is running. This is a very simplified version of the process, but it will work if you can't find the specifics.

Click to expand...

That's the way I've always done it, but once the heads come off to grind the valves, how far down do you tighten them before firing up the engine? With AMC engines it's easy -- tighten until it's tight against the shoulder on the stud, but the Chevy engines don't have a shoulder to tighten onto.

Eagle said:

That's the way I've always done it, but once the heads come off to grind the valves, how far down do you tighten them before firing up the engine? With AMC engines it's easy -- tighten until it's tight against the shoulder on the stud, but the Chevy engines don't have a shoulder to tighten onto.

Click to expand...

It has been too long since I've had the heads off of a Chevy to be real sure. I think that you set them with about .010" play. I may be wrong on that. I suppose that would be enough play to be sure the valves aren't staying open.
I don't want to give out bad advice, so I will check tomorrow at work and see what the GM techs have to say about it. I am pretty sure we have the GM manuals. I talked to a GM parts guy a while back about the GM engine in a Jeep deal, he said that GM sold AMC engines that were one model year old. Meaning that if you needed parts for your 86 Jeep, you ordered them for a 85 GM engine. Most of the time the parts from GM were cheaper than the parts from AMC/Chrysler.

Bryan

you want a 2.8L to stop tapping/knocking?!?

good luck, I mean it.. you'll NEED it.


I did mine by hand on the engine stand w/ the timing chain off. I just spun the cam and tightened them until there was no noticable play.

be aware of the part of the valve cover that goes over the intake manifold, apply a decent amount of RTV in a strip that is about 2" long that crosses the surface where the head and intake manfold meet. this is the only way to keep that POS from leakin (this will make sense when you have everything apart)

And you like VW's too! I just lost a 94 Golf 2.0L. If you have questions about that, let me know, I might be able to help.

I found the procedure in the 85 Commanche shop manual at work.
It says...

Rotate the engine to TDC #1 firing position. Turn out the adjusting nut untill you feel lash in the pushrod. Then turn in the adjusting nut until all lash is removed. This can be determined by rotating the pushrod while while turning the adjusting nut. When the lash has been removed, turn the adjusting nut 1 and 1/2 additional turns (to center the tappet plunger).

The following valves can be adjusted at TDC #1 firing position. Exhaust- 1,2,3 and Intake-1,5,6. Rotate the crankshaft one revoloution to the #4 firing position, then adjust the following valves, Exhaust-4,5,6 and Intake-2,3,4.

Hope this helps.

Bryan