valve adjustment

[livi]

Superb !

Thread printed out and nailed to the wall in my garage. Bump.

[diy83sc]

Valves adjusted - no guessing!

I picked up a set of gauges that among others included a .002, .0025, and .003 . My valves were already adjusted - at least I thought I did a good job. Well, this simple check found three loose and two tight! What I also learned is that the .002 is too soft and does not easily make it's way between the rocker and cam. I used the .0025 instead and had no issues. The toughest to do are #3 and #6. Other than that, this worked out great.

Doug, thanks again for sharing this great tip!

Tony

[khamul02]

I'm gearing up to do my first valve adjustment. I purchased a DVD & an old VHS tape. With these along with some reading, I thought I was ready. Now you guys introduce this thread & for the first time there seems to be some science to the whole "feel" thing. Btw, the vhs tape suggested that "feel" should have a magnitic type pull to it, whatever that means. Anywho, I'm a bit lost on the process you guys are taking about. Is there any way someone can take a pic of a feeler gauge inserted between rocker and cam? I'm confused on how exactly it is supposed to go in there.

[Wil Ferch]

Doug:

As you say..there is ( from a *practical* standpoint)...no real reason to split hairs, but we *are* talking about small numbers, so let me add this:

- the "official" Porsche spec is not really 0.004". We Americans use this as a round-off estimate to the *true* German ( metric) basis of 0.1 mm lash under the elephant's foot. Maybe the Porsche label does the same thing by saying 0.1 mm = 0.004", but in dual langauge applications, I would think the *core* number is that number used in the native language and measurement system. The "other" number carries a round-off error.

In actuality.... 0.1 mm = 0.0039". So we Americans target a slightly loose setting ( again...speaking mathematically, and not of any practical significance).

However, since we're manipulating numbers, it would be best to use the most accurate numerical methods possible...and then round-off at the very end of the procedure, instead of rounding along every step along the way. Error build-up ....dontcha' know.....

Anyway....here's where I'm slightly confused.

0.0039" / 1.4 rocker ratio = 0.0028" ..( or 0.0027" if 1.45 rocker ratio)

0.004" / 1.4 rocker ratio = 0.0029"... ( or 0.0028" if 1.45 rocker ratio).

In both cases, true enough...the rocker ratio question narrows the numbers down by 1 ten-thousandths of an inch...no worries....

...but I can't duplicate your 0.00272" or 0.00285" numbers.

Again, only from a "math" standpoint.... why?

BTW....I used to use the Porsche tool P-213 or P-213B. I have various versions of this tool and I miked all my blades. ALL of them miked out to between 0.0042" and 0.0044". Interesting, huh ???

- Wil

[2.7RACER]

Wil,
First thanks for your interest.
The numbers are from dividing .003937 by 1.45= .002715172
and dividing .004 by 1.40= .002857143.
So by rounding it looks like .00272 and really .00286 rather than .00285.
I'm not positive what the actual designed rocker ratio is. I've heard different numbers and of course if you look at the motion it is obvious it changes as the rocker goes from the base circle to the tip of the lobe.
I'm only interested in the ratio at the base circle.
So the numbers above represent the range.
Until I beat on my HP calculator I didn't really know the range.
I just stumbled upon all this when I was adjusting valves a couple years ago. It was just easier to slide the feeler guage in between the rocker and cam.
It wasn't until just recently, (last winter), that I actually calculated what I was doing and then did the measurements on my 2.7 race car with the motor out.
I'm new to all this and I realize the pro's do this every day and don't need to go thru all this.
But after thinking about it, us once a year guys have a way to check ourselves.
My problem is I'm retired, so I have time to think about esoteric stuff like this.
Thanks to you, and so many of the real pro's on this board, I've learned a ton of great info.
Just got my 7:31 915 transaxle into my race car today. I can't wait to try it out at the local track. Went from a 8:31.
I'm having fun,

[Wil Ferch]

Doug:

Thanks...but I'm far from being a pro...an "interested amateur" on all things Porsche perhaps....

Also thanks for the numerical clarification... makes sense.

- Wil

[Nine9six]

Originally posted by 2.7RACER
When the foot to valve gap is at .004" the gap between the rocker and the back side of the cam works to .00285" This is too close to allow a .003" shim in. So now you have a "over guage" If the .003" shim fits your setting is loose.

Its to close to allow a .003 shim in because it is LESS than .003. Not because its to close to allow a .003 shim in.
Example: a 1/16" gage pin (.0625), will NEVER fit into a 1/16" ((.0625) hole. Why? Because two equal dimensions cannot physically occupy the same space.
Other than that, this is an excellent tip!

[Nine9six]

Originally posted by Wil Ferch
BTW....I used to use the Porsche tool P-213 or P-213B. I have various versions of this tool and I miked all my blades. ALL of them miked out to between 0.0042" and 0.0044". Interesting, huh ???
- Wil

Then something is wrong...Micrometer is out of tolerance, or shim blades are not to size.
I am siding with the mic being in need of adjustment (calibrated).
However, if the mic is worn from excessive use within that range; it might be time to replace it. You could alway apply a compensating factor if the mic measurement error is consistently repeatable.

[Wil Ferch]

The micrometer used was a calibrated instrument borrowed from the machine shop from work....no issues there. The blades were all fat, no question. I state this as a finding...and wonder what others have found. Maybe nobody else took the plunge to mike them.

- Wil

[jdowty3]

I just did a valve adjustment using the Island tool. Soooo much easier.

[Wil Ferch]

Th point on this thread however, is the "new" idea about measuring from the backside...not under the elephant's foot.

Granted, the Island tool will make measuring from the normal position easier, but this idea about measuring from the backside has this idea beat too...IMHO....

- Wil

[Gunter]

Good stuff.
I'll check that out on my next.
Nine9six: Your observation is true. Generally, fitting a given diameter bore onto the exact same diameter shaft is called a "press-fit".
Can also be a "Shrink-fit" if heat is applied.

[captainrb]

How or where can I get one of those island valve adjustment tools??? I just had my valve covers surfaced(as per a thread on this site) now there back from the machine shop. Sure would like to try out the island tool. D.C.

[Wil Ferch]

Don't think the Island tool ( feeler gauge) has a particular advantage if you measure on the backside as discussed here. A "normal" longish feeler gauge shim shoiuld work perfectly here.....

The island tool should work better if you measure under the elephant's foot , the normal way as done forever.

- Wil

[diabolos88]

going to attempt my 1st valve adj in the AM. great thread, glad I bumped into it

[kqw]

Originally posted by Wil Ferch
The micrometer used was a calibrated instrument borrowed from the machine shop from work....no issues there. The blades were all fat, no question. I state this as a finding...and wonder what others have found. Maybe nobody else took the plunge to mike them.

- Wil

Good point Wil...

I "Mic" my blades before use. I also use the proper storage of the micrometer to ensure it stays in spec. i.e., I store in the case, place in dry environment and back the ends off a bit so they are not touching.

[khamul02]

Just to verify. This is the gap we are talking about.

And is this the direction (via arrows) that we would insert a standard feeler gauge blade.

[livi]

Excellent picture ! This thread should be a sticky. Bump.

My beauty is due for an adjust this summer. I hesitate to try as I have never done it before and have no previous mechanical experience engine wise. Still, I am tempted. Would probably be the most proud moment this year for me.

My previous projects have been executed with the car on jack stands (shocks, tie rods, brakes, gear lube ). Me cramped under it on the concrete floor. An orthopedically unsatisfying position, to say the least. Still doable.

What about valve adjust ? Possible lying on the back cramped under the car ?

Also, this new method - any more of you tried it ?

Ultimately, taking in account the above, would you recommend I give it a try or just simply leave it to the shop ?

[tldry]

Right in the middle of my first valve adjust. Taking it very slowly and overly cautious. Greatest PITA thus far has been getting things out of the way (AC, heater hoses). Number 6 sucks to do and suspect #3 will as well. Had difficulty finding the right feel with the traditional method so I'm combining it with 2.7Racer's. I'm "roughing it in" the traditional way and then tightening it up against a .003. Thus far I'm satisfied the result is as good as I can get it.

If I can do this anyone can.

[diabolos88]

thanks for that great jpg, Ill be needing it when I dive in for my valve adjustment