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V6 Discussion and questions about the base carbureted or MPFI V6's and the rare SFI Turbo V6.

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Old 03-08-2003, 09:57 PM   #1
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Join Date: Mar 2002
Location: Dallas, TX
Posts: 594
Car: '89 Chevrolet Camaro IROC-Z
Engine: L98
Transmission: TH-700R4
Axle/Gears: B&W 2.77 Posi

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Valve adjustment on a 2.8L V6...

I think I've got a valve ticking somewhere on my engine, and I've always heard that the best way to adjust them is with the engine running. I've done it like this before on an L98 engine before, and the process was pretty straightforward.

But, just looking at my V6, it seems like it will be a lot more work. From the looks of it, the whole intake, the coil, and all of the EGR stuff will have to come off just to get to both valve covers. And, to actually adjust, I'll have to put all of that back on, minus the valve covers, just to run the engine. Then it will all have to come off again to replace the valve covers, and then put it all back on.

Is all of that necessary just to adjust the valves? Or am I just wrong in thinking that that much will have to come off to get the valve covers off?

If there's an easier way to do this, I'd like to know...

Thanks!
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Daily Driver: '89 Camaro IROC-Z (5.7L V8 TPI, 4spd automatic) - Victory Red
For Sale: '88 Camaro SC (2.8L V6 MPFI, 4spd automatic) - Yellow
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Old 03-09-2003, 12:18 AM   #2
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Its a pain in the *** with these motors . The oil retainer rocker clips will not fit under the MPFI. Oil gets everywhere.
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Old 03-09-2003, 10:28 PM   #3
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Pushing this back up to the tops so more ppl will see it.
I am sure there is more advice to be heard on the subject.
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Old 03-09-2003, 10:43 PM   #4
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FROM WHAT I UNDERSTAND
Await the cam lobes to rotate to postion to allow valves of EACH CYLINDER, to stay close.
Tighten rocker arm til pushrod don't spin.
AND I've used a cyliner compressor to adjust valves. I adjusted til I got highest cylinder compresion reading.
I did this on my Firebird & worked perfect.
I used this same theory on my Blazer (see below). THIS TIME, my valves tick-ever so slightly, thus I'm going back in to adjust.
BUT FIRST, before I crack a valve cover off, I'm taking a stethoscope to each cylinder, to isolate the offending valves.
Upon cover removal, I will check my theory, with all valves.
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1985 Firebird 2.8->3.4 swap project
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Old 03-09-2003, 11:20 PM   #5
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Car: 1986 Firebird
Engine: 2.8 V6
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From the books, the way to adjust the valves:

Quote:
Originally posted by TomP
Woah, don't torque those rocker nuts down. Unless you've changed something that you didn't mention, our v6's (2.8/3.1) have hydraulic lifters. You don't set lash manually with a feeler gauge, and you don't go torquing anything down all the way, either!

A hydraulic lifter has a spring inside. You torque the rocker nut down until "zero lash" is reached, and then you turn the rocker nut an additional 180 degrees. This preloads the rocker. This is the non-expensive-gauge way to set up the hydraulic lifters. By going an extra 180 degrees on the nut, you start pushing the pushrod into the hydraulic lifter. Because of the threading of the stud, every little bit you turn the nut, the pushrod presses into the lifter by a certain measurement, for example, 0.010". So by turning the nut 180 degrees, you set the lifter up so it can be self adjusting- as all hydraulic flat-tappet lifters are. This information is directly from the 1986 GM Service Manual, and applies to all 82-92 motors, since they all used the same lifters.

You can't just go tightening for zero lash; you need to rotate the crank in order to get the valves to close. By bringing certain pistons up to TDC, you ensure that some valves are closed- and those are the ones you'd set. From what I remember, it's a four-step procedure (need to turn the crank 4 times before all are set up properly.) The end result of the procedure is the same- all pushrods are "sunken" into each lifter by the same amount. When the lifter "pumps up" with oil, the oil each lifter absorbs allows it to self adjust.

Zero lash is felt on a pushrod when the valve is closed, and the rocker nut is loose (or off). Start tightening the rocker nut as you jiggle the pushrod up and down. If there's play in the pushrod, you'll feel it "tap" against the rocker arm (upward motion) and tap against the lifter. Once that pushrod won't jiggle up/down anymore, you're at zero lash. Another way to find zero lash is by lightly spinning the pushrod- at zero lash, the pushrod will stop spinning since it's sandwiched between the rocker arm and lifter top- but this isn't too hot of a method- say you've got a heavier grip on the pushrod than I would, you might spin the pushrod for longer, and go past zero lash.
Find more information in that same message, at http://www.thirdgen.org/techbb2/show...hreadid=160103 . You don't need to have the motor running while adjusting the valves- we run hydraulic lifters, not solid lifters. Make sure you don't have an injector ticking, or, an exhaust leak at one of the manifolds (broken bolt) that causes a tick sound.
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Old 03-10-2003, 12:44 PM   #6
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TomP: You know what? When I was under my car to drain the coolant from the block for the timing chain swap, I did notice that one of the rear exhaust manifold bolts was sticking out about a half-an-inch. I suppose that could making a ticking sound, couldn't it?

I wanted to tighten it, but that thing is rusty and pretty much jammed in there. I'm afraid I might break it off...


Thanks for the info.
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Old 03-10-2003, 04:16 PM   #7
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What ya do.
GO TO THE WRECKING YARD & grab a complete different set of the bolts.
Get new exhaust maifold gaskets & replace all the bolts & add a gasket.
Can get away without a new manifold to pipe gasket if careful.
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1985 Firebird 2.8->3.4 swap project
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Old 03-10-2003, 04:16 PM
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