Loose valves - 4-5 thou' on backside?

[Jonny042]

Hello all,

Well, while I am waiting for clutch (repair) parts to arrive I am doing all sorts of fun things like setting my valves.

I found that ALL my valves were quite loose, every single one would take a .004" feeler up the backside, some even a .005", and one a .006".

So I've gone for a nice snug .0025" and am satisfied that I have done it correctly and quadruple checked them all.

Of course the suspense is killing me....... will my car actually be quieter by a significant margin? will it run better, idle smother, and all that? It will be several weeks before I find out for myself.

Thanks!!

Jon

[kidrock]

my personal experience is even when adjusted correctly, your valve train may be somewhat noisier after an adjustment. Valve lash tends to tighten (and become quieter) between adjustments.

Car should run smoother....how much so will depend on how long it's been since the last adjustment.

But just because there may be a slight clatter doesn't mean there should be an irritating clash.

[jstobo]

The spec is .004". You may damage your valves if they are too tight.

[john walker's workshop]

backside method is plus/minus. (ball park). the proper way, using the proper tool under the rocker swivel foot, is .004" exactly.

[2.70Racer]

The plus minus of the backside method is .0035" to .0042".
This method eliminates the need to develop a feel for the "magnetic" pull.
People that do this for a living should have developed the "feel" early in their career.
Those of us that adjust valves once a year, have no need to develop the "feel" with the backside method.
With the backside method you can easily check the adjustment without loosening every valve.
Saves time and is accurate.

[Joe Bob]

With a big adjustment on all valves, I would suspect the "adjustment" b all fuch'd up......

But hey, I could be wrong.......

[Jonny042]

Originally Posted by Joe Bob

With a big adjustment on all valves, I would suspect the "adjustment" b all fuch'd up......

But hey, I could be wrong.......

I agree........ somebody fuch'd up. Better make sure it wasn't me!!

I was under the impression that "go" with a .0025 and a "no go" with .003 was the way to do the backside method? This should net you at least .0035 at the valve, well within the factory spec?

Anyway, didn't intend to start a debate on the merits of frontside/backside.

[Joe Bob]

Then make sure y'didz it right.....this ain't yer Daddyz Buick.....

I'm serious, if it ran well prior to the "adjust"....then.....hmmmmmm....know what I mean?

[Jonny042]

I haven't owned the car for long, but everything else I look at has bee half-assed or just plain wrong so I don't really have much faith in the PO's mechanic.

.004" x 1.4 = .0056"........ = every valve at least .0016 too loose.

My only question was, is this going to make a big difference in how noisy the valves are? I mean, they weren't noisy all the time, only when the engine was running.

And I'm pretty sure buicks have had hydraulic lifters since before I was born.

[Jonny042]

Originally Posted by 2.70Racer

The plus minus of the backside method is .0035" to .0042".
This method eliminates the need to develop a feel for the "magnetic" pull.
People that do this for a living should have developed the "feel" early in their career.
Those of us that adjust valves once a year, have no need to develop the "feel" with the backside method.
With the backside method you can easily check the adjustment without loosening every valve.
Saves time and is accurate.

Sorry. I see what you're saying. We are both right.

[s5uewf]

I think Porsche 911 valve clearance actually increases as the engine gets hotter as part of the design. So, if you have clearance when adjusting, you'll have clearance when driving it.

Some other vehicles are set up so clearance closes when the engine warms up, which would make having adequate valve gap much more critical.

I believe the biggest reason you need to make sure your valve clearance is within spec on a 911 is to allow the valve to contact the valve seat long enough while closed to transfer heat to the head, to help keep the valves cooler.

[kidrock]

Originally Posted by john walker's workshop

backside method is plus/minus. (ball park). the proper way, using the proper tool under the rocker swivel foot, is .004" exactly.

Here we have a gentleman who owns his own Porsche repair shop, giving an example of the correct way to do a specific job.

Why do we have so many other people that want to reinvent the wheel?

[Bob Kontak]

I have used a dial indicator to measure the 0.004" between foot and valve, is that an acceptable method?

[2.70Racer]

Kidrock,
Read my post #5 for your answer.

[LakeCleElum]

Originally Posted by kidrock

Here we have a gentleman who owns his own Porsche repair shop, giving an example of the correct way to do a specific job.

Why do we have so many other people that want to reinvent the wheel?

Amen Brother.............Been doing valves on motorcycles since 1966.....Just do it like the manual sez and forget all about this "go-no go" stuff.........Itn's not rocket science..........

[j911brick]

Originally Posted by kidrock

Why do we have so many other people that want to reinvent the wheel?

Because that is what the world is about. If man wasn't always trying to improve things and make them better we would still be living in the stone age. Times change and technologies change. Even Porsche changes things every year because they figure out how to do it better.

[kidrock]

I admit it, I'm a dinosaur. I've been doing it this way since I owned my first VW in 1980, and I just feel more comfortable doing it the original way.

I guess I find a little solace in knowing that a well-respected specialist still recommends doing it the way that Mr. Bentley and our own workshop manuals prescribe.

Whatever floats yer boat, as long as the results are successful.