911 Valve Adjustment Made Easy!!!

[Wayne 962]

Just dropping a little note here to let everyone know that I have finished our most requested tech article. You can check it out at:
http://www.pelicanparts.com/techarticles/911_valve_adjust/911_valve_adjust.htm

Thanks a bunch, and please let me know if you have any questions.

-Wayne

[oly]

Wow, 11 years since you started this thread and nobody posted questions here!

I have a questions about these two sentences:

"Leaving the feeler gauge placed in-between the valve stem and the screw foot, tighten down the retaining nut. Remove the feeler gauge, and recheck the clearance."

I assume that this means:
a1. Leaving the feeler gauge placed in-between the valve stem and the screw foot, tighten down the retaining nut.
a2. Check for the correct gauge resistance. If you have the correct resistance, go to b. If you don't have the correct resistance, got to a1.
b. Remove the feeler gauge.
c. Recheck the clearance by reinserting the gauge and feeling for the correct resistance.

My questions are:

1. Is my assumption right?

2. If it is right, why would the gap change between these two checks?

3. It seems like it might be better to do a1., a2., and b., then rotate the engine until it was back to the same cylinder being at TDC, then do c. Could this be a more efficient way to do the adjustment since cycling the system once is more likely to cause the gap to change?

4. Or is the reason for rechecking only intended to make sure that your measurement technique was correct?

And even though I'm about 11 years late, MANY thanks for writing the article and making it available Wayne!

[Rob B]

The gap may change as you tighten the lock nut if the adjusting screw is alowed to rotate. Sometimes it just wants to turn with the lock nut. Rob

[Christien]

Damn, I thought maybe Wayne had discovered a new way of adjusting valves that saved all the back ache!

Art, Rob is correct - even though sometimes the gap feels right when you pull the gauge out, it sometimes doesn't go back in properly. And the feeling of resistance is the most difficult part. I was very lucky and had a factory-trained Porsche mechanic show me what proper resistance should feel like.

[mca]

Originally Posted by Christien

I was very lucky and had a factory-trained Porsche mechanic show me what proper resistance should feel like.

A local shop was kind enough to show me the same. However I still can't get a hang of the traditional method and prefer the backside method.

I just can't get that tool in the tight spaces without bending the feeler. Once it gets wonky it is useless. Probably need to watch someone do it again.

[kodioneill]

I know this is nit picky but the cam chains run around the intermediate shaft not the crankshaft.

[oly]

I just edited by original post to change "a." to "a1." and added "a2." Hopefully this clarifies my interpretation.

Rob B & Christien,

If the retaining nut is tight and the gap is correct, why would you remove the gauge then put it back in?

[hbf]

What is the backside method?

HBF

[flatsixjunky]

One more time, thank you Wayne; I can't write this enough. Spring comes I'll be taking my first swing at it.

Take care everybody,

O-

[berettafan]

did some motorcycle valves (super duper easy access) this past year and have better confidence in being able to get the feel right next time.

[T77911S]

Originally Posted by mca

A local shop was kind enough to show me the same. However I still can't get a hang of the traditional method and prefer the backside method.

I just can't get that tool in the tight spaces without bending the feeler. Once it gets wonky it is useless. Probably need to watch someone do it again.

wonky?

[T77911S]

i have always found it easier to remove the feeler, losen the nut and turn the screw based on the angle from where it was, tighten the nut, then reinsert the gage. i have never had luck with leaving the gage in. i spend more time hunting for the right feel. usually the amount it needs to be changed is so small, going by the angle of the slot in the screw alows for more precise changes..... it works better for me.

[Formerly Steve Wilkinson]

mca, you know that you can't use a conventional feeler gauge to adjust 911 valves, right? Won't work. won't fit, gets all bent up.

There are a couple of special 911 feeler gauges, one the standard tool and another one that allows you to feed new gauge metal into the "feeling space" if the existing gauge metal gets bunged up. But you can't use a standard V8-valves tool.

[mca]

Originally Posted by Formerly Steve Wilkinson

mca, you know that you can't use a conventional feeler gauge to adjust 911 valves, right? Won't work. won't fit, gets all bent up.

There are a couple of special 911 feeler gauges, one the standard tool and another one that allows you to feed new gauge metal into the "feeling space" if the existing gauge metal gets bunged up. But you can't use a standard V8-valves tool.

Ha ... yes, i have the little bent specialty tool and about 5 feeler blades. Maybe my tool needs to be modified (ie. bent at a different angle). It didn't have the same shape as the one my local shop had.

When I try to get the tool in the tight space the tiny feeler will catch on things. Sometimes causing it to twist ... rendering the feeler useless. When I rebuilt the engine it was easy to do it on the stand. I just have a hard time doing it with the engine on the car.

Just being honest about my lack of adjusting skills with the engine in the car. The backside method is much easier for me.

[mca]

Originally Posted by hbf

What is the backside method?

HBF

Pelican Technical Article: 911 Valve Adjustment - The Backside Method

[hbf]

Thanks for that, MCA. So simple, so logical. So easy!

HBF

[Rob B]

There is another method used to get the "feel", it's called go-no go. The technique involves adding .002" and adjusting until the proper size fits but +.002" won't. There are feeler gauges that are manufactured with this feature on every blade. Rob

[Gunter]

Originally Posted by hbf

Thanks for that, MCA. So simple, so logical. So easy!

HBF

Wait until you do it the first time before thinking it's easy.

Both, Standard and Backside method have a few things in common:

Crammed spaces plus, a lot depends on the dexterity and skill of the person doing it.
Common mistakes are not keeping the 13mm wrench square on the nut, over-tightening the nut and rounding the hex.

For the backside method, the longer feelers will resist inserting and will bend before sliding in. Residual oil may be a help or a hinderance.

[MichaelN]

Simply excellent article. Took all the mystery out of the job, which is the biggest hindrance to getting started for the first time. One sentence made me curious, though.

"It is important not to over torque the nuts on the valve covers".

Why is it important? 4 ft-lbs the first time and 6 ft-lbs the second seems very exacting and quite "loose". What exactly are the consequences of over-tightening? I'm now concerned I may have done just that since I don't trust my "feel".

[rockaria]

I had never done a valve adjust before. I used the backside method from your article. Since it was the first time I went slow. I did take all weekend to do it and checked and messed with it hundereds of times before I was confident. My SC has never run better, Thanks Wayne!